canSAS - User contributions [en]

/GISANS - Advancing data reduction and analysis Workshop

2026-04-07T10:58:26Z

Annikastellhorn:

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]

==== Summary ====
Overall Summary

(i) ToF
* Instrument factors influence measurement strategies and tools are needed to aid this process.
* Background - effects of inelastic scattering can change background.
* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.
* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.
* ToF and mono mode have different data processing requirements!
** Spread of wavelength in ToF = possible quasi elastic events vs. Mono = assumption of elastic scattering
** this mostly impacts on Background: mostly inelastic

(ii) Multiple scattering
* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry
** They have to be identified before each experiment
* MS gives extra background: can be used to explicitly enhance signal
* X-ray comparison:
** X-rays: (mostly) strong absorption
** Neutrons:
*** absorption is weak and therefore scattering is of higher intensity.
*** Hydrogenabsorption strong
** Be careful when comparing the theory from GISAXS and GISANS!
* How to measure MS?
** GIXOS (grazing incidence X-ray offspecular scattering)
*** Scattering from the object is modulated by the reflectivity, you can deduce reflectivity if you estimate the form factor.
*** Example: ID10 ESRF

(iii) Background handling
* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

(iv) Normalization
* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
*** In NR: fit the data+background to the total signal (instead of substracting!)
** GISOXS?
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed! (Different normalization procedures at different beamlines)
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed
** Good to get a Survey "How is this done at different beamlines currently"?
** Using AI?: Should then contain: (i) dataset that is similar to the experiments (ii) what this data-set represents (physically)

* Data-reduction:
** Insert corrections for efficiency etc.,
** Uncertainty calculation reproducible?
*** Information on footprint, slits, .. (see detailed notes)
*** Further input to uncertainty apart from countrate?
* Comparison to SAS:
** GISAS = normalization to DB vs. SAS: = calculation of differential cross section (not possible in GISAS)

(v) Using SANS software
* Regarding BornAgain:
** Need a set of prototype models (check what is on the BA webpage) - especially for inexperienced users
*** This should include a very detailed description about its physical limitations, directly implemented into BA sending error messages if overgone.
*** Can we benefit from models in other software packages?
*** SasView: easy user-insertions of new form-factors - learn from that?
*** Package approach in BA problematic?
** Further good features to implement: (i) intensity w.r.t. direct beam, w.r.t multiple scattering background, w.r.t. general expected background (according to experience + commissioning).
** How to get fitting for GISANS working?
* Inspiration from X-ray programs: Brookhaven, Ben Ocko, BornAgain. Other: BoToSim, BoToFit, SpinW

(vi) Instrumentation
* Missing

(vii) Common data format
* Pros and Cons of seperating "reduction" and "analysis", i.e., having an instrument independent analysis without original raw information
** Pro:
*** datasets are transferable between softwares
** Con:
*** Throw away information?
*** Have to understand the inputs and what needs to be kept
*** How to calculate uncertainties?
* Why necessary to define in beginning: Once defined, file formats should not be altered, only extended (e.g. possible in nexus or cansas XML formats)
* Maybe not "throw away" raw counts after reduction, but keep all information? If suitable / manageable: Ask in Survey?

(ix) Magnetic Scattering]
* considering ".nxs" files and dimensions: A scan of everything/motor should be considered a dimension in the "nxs". It should not be restricted to 4 dimensions.
* On-the-fly polarization analysis: online corrections are good. But highest precision correction should be done at the end of the experiment before the users go home.
(x) Off-Specular
* Missing

==== Outlook ====
* Letter in "Neutron News"
* Need a survey on : (i) Normalization, Background handling, Instrumentation and (ii) Data formats

==== Detailed Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides: To come
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
[[File:TopervergGISANS2026ILL1-part1.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 1]]
[[File:TopervergGISANS2026ILL1-part2.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
[[File:HF McStas.pdf|thumb|Introduction on McStas - Henrich Frielinghaus]]
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
[[File:Gutfreund OffSpec new part 1.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 1]]
[[File:Gutfreund OffSpec new part 2.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
[[File:Magnetic GISANS.pdf|thumb|Talk on "Magnetic and PA-GISANS" from Annika Stellhorn]]
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

/GISANS - Advancing data reduction and analysis Workshop

2026-04-07T10:57:16Z

Annikastellhorn:

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]

==== Summary ====
Overall Summary

(i) ToF
* Instrument factors influence measurement strategies and tools are needed to aid this process.
* Background - effects of inelastic scattering can change background.
* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.
* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.
* ToF and mono mode have different data processing requirements!
** Spread of wavelength in ToF = possible quasi elastic events vs. Mono = assumption of elastic scattering
** this mostly impacts on Background: mostly inelastic

(ii) Multiple scattering
* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry
** They have to be identified before each experiment
* MS gives extra background: can be used to explicitly enhance signal
* X-ray comparison:
** X-rays: (mostly) strong absorption
** Neutrons:
*** absorption is weak and therefore scattering is of higher intensity.
*** Hydrogenabsorption strong
** Be careful when comparing the theory from GISAXS and GISANS!
* How to measure MS?
** GIXOS (grazing incidence X-ray offspecular scattering)
*** Scattering from the object is modulated by the reflectivity, you can deduce reflectivity if you estimate the form factor.
*** Example: ID10 ESRF

(iii) Background handling
* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

(iv) Normalization
* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
*** In NR: fit the data+background to the total signal (instead of substracting!)
** GISOXS?
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed! (Different normalization procedures at different beamlines)
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed
** Good to get a Survey "How is this done at different beamlines currently"?
** Using AI?: Should then contain: (i) dataset that is similar to the experiments (ii) what this data-set represents (physically)

* Data-reduction:
** Insert corrections for efficiency etc.,
** Uncertainty calculation reproducible?
*** Information on footprint, slits, .. (see detailed notes)
*** Further input to uncertainty apart from countrate?
* Comparison to SAS:
** GISAS = normalization to DB vs. SAS: = calculation of differential cross section (not possible in GISAS)

(v) Using SANS software
* Regarding BornAgain:
** Need a set of prototype models (check what is on the BA webpage) - especially for inexperienced users
*** This should include a very detailed description about its physical limitations, directly implemented into BA sending error messages if overgone.
*** Can we benefit from models in other software packages?
*** SasView: easy user-insertions of new form-factors - learn from that?
*** Package approach in BA problematic?
** Further good features to implement: (i) intensity w.r.t. direct beam, w.r.t multiple scattering background, w.r.t. general expected background (according to experience + commissioning).
** How to get fitting for GISANS working?
* Inspiration from X-ray programs: Brookhaven, Ben Ocko, BornAgain. Other: BoToSim, BoToFit, SpinW

(vi) Instrumentation
* Missing

(vii) Common data format
* Pros and Cons of seperating "reduction" and "analysis", i.e., having an instrument independent analysis without original raw information
** Pro:
*** datasets are transferable between softwares
** Con:
*** Throw away information?
*** Have to understand the inputs and what needs to be kept
*** How to calculate uncertainties?
* Why necessary to define in beginning: Once defined, file formats should not be altered, only extended (e.g. possible in nexus or cansas XML formats)
* Maybe not "throw away" raw counts after reduction, but keep all information? If suitable / manageable: Ask in Survey?

(ix) Magnetic Scattering]
* considering ".nxs" files and dimensions: A scan of everything/motor should be considered a dimension in the "nxs". It should not be restricted to 4 dimensions.
* On-the-fly polarization analysis: online corrections are good. But highest precision correction should be done at the end of the experiment before the users go home.
(x) Off-Specular
* Missing

==== Outlook ====
* Letter in "Neutron News"
* Need a survey on : (i) Normalization (ii) Data formats

==== Detailed Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides: To come
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
[[File:TopervergGISANS2026ILL1-part1.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 1]]
[[File:TopervergGISANS2026ILL1-part2.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
[[File:HF McStas.pdf|thumb|Introduction on McStas - Henrich Frielinghaus]]
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
[[File:Gutfreund OffSpec new part 1.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 1]]
[[File:Gutfreund OffSpec new part 2.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
[[File:Magnetic GISANS.pdf|thumb|Talk on "Magnetic and PA-GISANS" from Annika Stellhorn]]
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

/GISANS - Advancing data reduction and analysis Workshop

2026-04-07T08:44:28Z

Annikastellhorn:

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]

==== Summary ====
Overall Summary

(i) ToF
* Instrument factors influence measurement strategies and tools are needed to aid this process.
* Background - effects of inelastic scattering can change background.
* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.
* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.
* ToF and mono mode have different data processing requirements!
** Spread of wavelength in ToF = possible quasi elastic events vs. Mono = assumption of elastic scattering
** this mostly impacts on Background: mostly inelastic

(ii) Multiple scattering
* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry
** They have to be identified before each experiment
* MS gives extra background: can be used to explicitly enhance signal
* X-ray comparison:
** X-rays: (mostly) strong absorption
** Neutrons:
*** absorption is weak and therefore scattering is of higher intensity.
*** Hydrogenabsorption strong
** Be careful when comparing the theory from GISAXS and GISANS!
* How to measure MS?
** GIXOS (grazing incidence X-ray offspecular scattering)
*** Scattering from the object is modulated by the reflectivity, you can deduce reflectivity if you estimate the form factor.
*** Example: ID10 ESRF

(iii) Background handling
* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

(iv) Normalization
* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
*** In NR: fit the data+background to the total signal (instead of substracting!)
** GISOXS?
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed! (Different normalization procedures at different beamlines)
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed
** Good to get a Survey "How is this done at different beamlines currently"?
** Using AI?: Should then contain: (i) dataset that is similar to the experiments (ii) what this data-set represents (physically)

* Data-reduction:
** Insert corrections for efficiency etc.,
** Uncertainty calculation reproducible?
*** Information on footprint, slits, .. (see detailed notes)
*** Further input to uncertainty apart from countrate?
* Comparison to SAS:
** GISAS = normalization to DB vs. SAS: = calculation of differential cross section (not possible in GISAS)

(v) Using SANS software
* Regarding BornAgain:
** Need a set of prototype models (check what is on the BA webpage) - especially for inexperienced users
*** This should include a very detailed description about its physical limitations, directly implemented into BA sending error messages if overgone.
*** Can we benefit from models in other software packages?
*** SasView: easy user-insertions of new form-factors - learn from that?
*** Package approach in BA problematic?
** Further good features to implement: (i) intensity w.r.t. direct beam, w.r.t multiple scattering background, w.r.t. general expected background (according to experience + commissioning).
** How to get fitting for GISANS working?
* Inspiration from X-ray programs: Brookhaven, Ben Ocko, BornAgain. Other: BoToSim, BoToFit, SpinW

(vi) Instrumentation
* Missing

(vii) Common data format
* Notes from group (?) to be inserted

(ix) Magnetic Scattering]
* considering ".nxs" files and dimensions: A scan of everything/motor should be considered a dimension in the "nxs". It should not be restricted to 4 dimensions.
* On-the-fly polarization analysis: online corrections are good. But highest precision correction should be done at the end of the experiment before the users go home.
(x) Off-Specular
* Missing

==== Outlook ====
* Letter in "Neutron News"
* Need a survey on : (i) Normalization (ii) Data formats

==== Detailed Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides: To come
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
[[File:TopervergGISANS2026ILL1-part1.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 1]]
[[File:TopervergGISANS2026ILL1-part2.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
[[File:HF McStas.pdf|thumb|Introduction on McStas - Henrich Frielinghaus]]
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
[[File:Gutfreund OffSpec new part 1.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 1]]
[[File:Gutfreund OffSpec new part 2.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
[[File:Magnetic GISANS.pdf|thumb|Talk on "Magnetic and PA-GISANS" from Annika Stellhorn]]
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

/GISANS - Advancing data reduction and analysis Workshop

2026-04-07T08:29:08Z

Annikastellhorn:

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides: To come
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
[[File:TopervergGISANS2026ILL1-part1.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 1]]
[[File:TopervergGISANS2026ILL1-part2.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
[[File:HF McStas.pdf|thumb|Introduction on McStas - Henrich Frielinghaus]]
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
[[File:Gutfreund OffSpec new part 1.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 1]]
[[File:Gutfreund OffSpec new part 2.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
[[File:Magnetic GISANS.pdf|thumb|Talk on "Magnetic and PA-GISANS" from Annika Stellhorn]]
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
Overall Summary

(i) ToF
* Instrument factors influence measurement strategies and tools are needed to aid this process.
* Background - effects of inelastic scattering can change background.
* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.
* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.
* ToF and mono mode have different data processing requirements!
** Spread of wavelength in ToF = possible quasi elastic events vs. Mono = assumption of elastic scattering
** this mostly impacts on Background: mostly inelastic

(ii) Multiple scattering
* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry
** They have to be identified before each experiment
* MS gives extra background: can be used to explicitly enhance signal
* X-ray comparison:
** X-rays: (mostly) strong absorption
** Neutrons:
*** absorption is weak and therefore scattering is of higher intensity.
*** Hydrogenabsorption strong
** Be careful when comparing the theory from GISAXS and GISANS!
* How to measure MS?
** GIXOS (grazing incidence X-ray offspecular scattering)
*** Scattering from the object is modulated by the reflectivity, you can deduce reflectivity if you estimate the form factor.
*** Example: ID10 ESRF

(iii) Background handling
* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

(iv) Normalization
* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
*** In NR: fit the data+background to the total signal (instead of substracting!)
** GISOXS?
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed! (Different normalization procedures at different beamlines)
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed
** Good to get a Survey "How is this done at different beamlines currently"?
** Using AI?: Should then contain: (i) dataset that is similar to the experiments (ii) what this data-set represents (physically)

* Data-reduction:
** Insert corrections for efficiency etc.,
** Uncertainty calculation reproducible?
*** Information on footprint, slits, .. (see detailed notes)
*** Further input to uncertainty apart from countrate?
* Comparison to SAS:
** GISAS = normalization to DB vs. SAS: = calculation of differential cross section (not possible in GISAS)

(v) Using SANS software
* Regarding BornAgain:
** Need a set of prototype models (check what is on the BA webpage) - especially for inexperienced users
*** This should include a very detailed description about its physical limitations, directly implemented into BA sending error messages if overgone.
*** Can we benefit from models in other software packages?
*** SasView: easy user-insertions of new form-factors - learn from that?
*** Package approach in BA problematic?
** Further good features to implement: (i) intensity w.r.t. direct beam, w.r.t multiple scattering background, w.r.t. general expected background (according to experience + commissioning).
** How to get fitting for GISANS working?
* Inspiration from X-ray programs: Brookhaven, Ben Ocko, BornAgain. Other: BoToSim, BoToFit, SpinW

(vi) Instrumentation
* Missing

(vii) Common data format
* Notes from group (?) to be inserted

(ix) Magnetic Scattering]
* considering ".nxs" files and dimensions: A scan of everything/motor should be considered a dimension in the "nxs". It should not be restricted to 4 dimensions.
* On-the-fly polarization analysis: online corrections are good. But highest precision correction should be done at the end of the experiment before the users go home.
(x) Off-Specular
* Missing

==== Outlook ====
* Letter in "Neutron News"
* Need a survey on : (i) Normalization (ii) Data formats

/GISANS - Advancing data reduction and analysis Workshop

2026-04-07T08:28:13Z

Annikastellhorn:

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides: To come
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
[[File:TopervergGISANS2026ILL1-part1.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 1]]
[[File:TopervergGISANS2026ILL1-part2.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
[[File:HF McStas.pdf|thumb|Introduction on McStas - Henrich Frielinghaus]]
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
[[File:Gutfreund OffSpec new part 1.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 1]]
[[File:Gutfreund OffSpec new part 2.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
[[File:Magnetic GISANS.pdf|thumb|Talk on "Magnetic and PA-GISANS" from Annika Stellhorn]]
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
Overall Summary

(i) ToF
* Instrument factors influence measurement strategies and tools are needed to aid this process.
* Background - effects of inelastic scattering can change background.
* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.
* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.
* ToF and mono mode have different data processing requirements!
** Spread of wavelength in ToF = possible quasi elastic events vs. Mono = assumption of elastic scattering
** this mostly impacts on Background: mostly inelastic

(ii) Multiple scattering
* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry
** They have to be identified before each experiment
* MS gives extra background: can be used to explicitly enhance signal
* X-ray comparison:
** X-rays: (mostly) strong absorption
** Neutrons:
*** absorption is weak and therefore scattering is of higher intensity.
*** Hydrogenabsorption strong
** Be careful when comparing the theory from GISAXS and GISANS!
* How to measure MS?
** GIXOS (grazing incidence X-ray offspecular scattering)
*** Scattering from the object is modulated by the reflectivity, you can deduce reflectivity if you estimate the form factor.
*** Example: ID10 ESRF

(iii) Background handling
* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

(iv) Normalization
* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
*** In NR: fit the data+background to the total signal (instead of substracting!)
** GISOXS?
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed! (Different normalization procedures at different beamlines)
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed
** Good to get a Survey "How is this done at different beamlines currently"?
** Using AI?: Should then contain: (i) dataset that is similar to the experiments (ii) what this data-set represents (physically)

* Data-reduction:
** Insert corrections for efficiency etc.,
** Uncertainty calculation reproducible?
*** Information on footprint, slits, .. (see detailed notes)
*** Further input to uncertainty apart from countrate?
* Comparison to SAS:
** GISAS = normalization to DB vs. SAS: = calculation of differential cross section (not possible in GISAS)

(v) Using SANS software
* Regarding BornAgain:
** Need a set of prototype models (check what is on the BA webpage) - especially for inexperienced users
*** This should include a very detailed description about its physical limitations, directly implemented into BA sending error messages if overgone.
*** Can we benefit from models in other software packages?
*** SasView: easy user-insertions of new form-factors - learn from that?
*** Package approach in BA problematic?
** Further good features to implement: (i) intensity w.r.t. direct beam, w.r.t multiple scattering background, w.r.t. general expected background (according to experience + commissioning).
** How to get fitting for GISANS working?
* Inspiration from X-ray programs: Brookhaven, Ben Ocko, BornAgain. Other: BoToSim, BoToFit, SpinW

(vi) Instrumentation
* Missing
(vii) Common data format
* Missing
* Missing
(ix) Magnetic Scattering]
* considering ".nxs" files and dimensions: A scan of everything/motor should be considered a dimension in the "nxs". It should not be restricted to 4 dimensions.
* On-the-fly polarization analysis: online corrections are good. But highest precision correction should be done at the end of the experiment before the users go home.
(x) Off-Specular
* Missing

==== Outlook ====
* Letter in "Neutron News"
* Need a survey on : (i) Normalization (ii) Data formats

/GISANS - Advancing data reduction and analysis Workshop

2026-04-07T08:04:00Z

Annikastellhorn:

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides: To come
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
[[File:TopervergGISANS2026ILL1-part1.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 1]]
[[File:TopervergGISANS2026ILL1-part2.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
[[File:HF McStas.pdf|thumb|Introduction on McStas - Henrich Frielinghaus]]
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
[[File:Gutfreund OffSpec new part 1.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 1]]
[[File:Gutfreund OffSpec new part 2.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
[[File:Magnetic GISANS.pdf|thumb|Talk on "Magnetic and PA-GISANS" from Annika Stellhorn]]
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
Overall Summary

(i) ToF
* Instrument factors influence measurement strategies and tools are needed to aid this process.
* Background - effects of inelastic scattering can change background.
* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.
* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.
* ToF and mono mode have different data processing requirements!
** Spread of wavelength in ToF = possible quasi elastic events vs. Mono = assumption of elastic scattering
** this mostly impacts on Background: mostly inelastic

(ii) Multiple scattering
* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry
** They have to be identified before each experiment
* MS gives extra background: can be used to explicitly enhance signal
* X-ray comparison:
** X-rays: (mostly) strong absorption
** Neutrons:
*** absorption is weak and therefore scattering is of higher intensity.
*** Hydrogenabsorption strong
** Be careful when comparing the theory from GISAXS and GISANS!
* How to measure MS?
** GIXOS (grazing incidence X-ray offspecular scattering)
*** Scattering from the object is modulated by the reflectivity, you can deduce reflectivity if you estimate the form factor.
*** Example: ID10 ESRF

(iii) Background handling
* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

(iv) Normalization
* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed

(v) Using SANS software
* Regarding BornAgain:
** Need a set of prototype models (check what is on the BA webpage) - especially for inexperienced users
** This should include a very detailed description about its physical limitations, directly implemented into BA sending error messages if overgone.
** Further good features to implement: (i) intensity w.r.t. direct beam, w.r.t multiple scattering background, w.r.t. general expected background (according to experience + commissioning).
* Inspiration from X-ray programs: Brookhaven, Ben Ocko, BornAgain

(vi) Instrumentation
* Missing
(vii) Common data format
* Missing
* Missing
(ix) Magnetic Scattering]
* considering ".nxs" files and dimensions: A scan of everything/motor should be considered a dimension in the "nxs". It should not be restricted to 4 dimensions.
* On-the-fly polarization analysis: online corrections are good. But highest precision correction should be done at the end of the experiment before the users go home.
(x) Off-Specular
* Missing

==== Outlook ====
* Letter in "Neutron News"

/ToF-GISANS

2026-04-07T07:45:49Z

Annikastellhorn:

Time-of-Flight GISANS (near surface scattering) involves all of the issues that have been raised under other topics but some are of particular importance:

* Instrument factors influence measurement strategies and tools are needed to aid this process.

* Background - effects of inelastic scattering can change background.

* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.

* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.

These highlights drawn from summary discussion should be edited and extended after more input from breakout group discussion.

Detailed notes group (?):
* ToF and mono mode - different data processing requirements. You have a spread of WL, an event mode dataset, whether it is quasi elastically scattered when it arrives on the detector. Mono instrument with no WL recording: making an assumption the signal is elastic. Elastic scattering is predominant but the background its often inelastic.

/Normalization

2026-04-07T07:45:24Z

Annikastellhorn:

Short summary from discussions/breakouts:
* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed

Notes:
* for normalization it should be taken into account hand-in-hand: Specular reflectivity measured and simulated via Parrat and Off-specular/GISANS measured and simulated via DWBA!
** Can NR help as a "reference" to normalize the GISANS measurement correctly - should it always go together?
** This is not possible for some of the existing beamlines where GISANS can be performed but NR not, especially for Monochromatic sources!
** At Tof-GISANS beamlines one could aim at getting the "NR" by measuring GISANS at different incident angles
* Another problem: we loose information on the background and on the correct normalization factor by the fact that we do not measure the whole real space anyhow, as the detector has finite size
* there are two different problems:
** a fully quantitative measurement and
** a reference to "1", where it would depend on the sample and the physics to be measured how to normalize (e.g., superconducting systems: with ref. via the T>Tc state, magnetic systems: with reference via the saturated state) BUT: this reference to "another sample state" is not for all systems possible. What then?
* Regarding the question "can magnetic references help" - this can not generally be done, as changing the layer system would impact on the sld, the background, the normalization, etc.
* Does the "correct normalization" only get critical if the background level is that high that changing the background in the simulation would change the simulated sld? Is that the same in NR and GISANS?
* What can you get from Q=0 in a GISANS measurement? Can one at all extract a quantitave solution from a GISANS measurement? Should rather we aim at always having proper reference systems that the cross section can be compared with for getting the physical parameters needed?

Notes group (?):
* Instrumental effects, one might need to worry about a few things. Normalisation in GI is very challenging. It would be nice for people to say what they have done but not sure what the best practise would be.
* Regarding data reduction:
** The approaches are not uniform if one is measuring the direct beam for normalisation monitoring. One has to put in corrections for efficiency etc. In SAS you are not concerned by normalising to the beam intensity but try to evaluate the differential scattering cross-section. This will be related to the amount of sample in the beam and is putting a constraint on models. If the sample is a sphere in a medium of something else one has to define the cross-section. In GI one can not identify the differential cross-section.

** Not obvious that in GISANS experiments everyone measures the incident beam intensity in the same way. A reference sample is very difficult and not the same as for SAS experiments. Many of the detectors will be damaged by the direct beam, at least it will not come linearly. One needs to know the WL distribution for the ToF instruments, the WL can be not the same as for the direct beam. This becomes something one has to define rather carefully. This is true for reflectometry as well.

** In the reduced file the raw counts are lost. People say the reduction should estimate the statistical uncertainty but it is not easy. The uncertainty for the measured intensity, one has to keep the footprint, are the slits reproducible? It can be one of the least precise things. 2 um on 20 um is 10% error. If one has very few counts it is a problem of statistics. One may have zeros in bins, one rebins to have 10-15 counts in bins… For GISANS there is not much beam. Along with the counts one needs to provide other sources of uncertainty. Sometimes people throw away a lot of information.

* Regarding NR comparison:
** In NR we can often get few counts and they turn zero after background subtraction, they datapoints disappear after taking a log. With few counts one can instead of subtracting the background fit the data+background to the total signal. One can measure background with the same poisson statistics. One has to measure with the same statistics and not just randomly subtract.

** Oversubtraction of background can drastically change the fitting result in NR. Understanding errors is complicated. Statistically correct way of doing things in terms of making a model, numerically it is unstable and has a lot of problems, fitting is tricky. Least squares is stable, other things are less so.

** The ultracontemporary methods, AI? This is a topic for tomorrow.
Provide training datasets have to be sufficiently similar to the experiment you are doing. To train you have to give not the dataset but also teach what it is representing.

******
******

/Common Data Format

2026-04-07T07:42:42Z

Annikastellhorn:

Detailed notes group (?):
* (repeated in Multiple Scattering Discussion):
** The package approach in BA might cause issues while SASview does not have them. Once the interface is defined it is hard to change it, same for the file format. One can design them to be extensible (NEXUS), to use new features. One has to think carefully what you insist people provide. For SAS data format, reflection format you need to provide certain information. The idea was that it can be extensible and if information is not provided it is simply skipped.
*** canSAS XML was developed for this. But people don’t use it in a right way, they don’t fill out the fields, data has incorrect format. It is not easy to solve these problems.
** The challenge with BA is that we don’t understand what is the input data. Originally was built around a monochromatic instrument with cartesian coordinates around the scattered beam. Strictly speaking SASview works in q space and it doesn’t assume anything about the detector space.
** One of the differences is how to make the software instrument independent. SASview: you provide reduced data where you have taken out all the instrument effects. The idea of q resolution without WL and angle, it can accommodate data from instruments with multiple detectors, you can concatenate them in one file.
** Before software for SAS used to compare errors if you have an area detector there are many pixels that goes to the same bin. What is the variation pix to pix in there. Statistics over the individual pixels is compared with the variation. One needs to have more information to test that. When it comes to model fitting you don’t trouble the fitting program with too complicated procedure at the moment. The peak fitting for diffraction already causes people a lot of problems. Once you try to correct for more things you get more uncertainties.
** With GISANS you re not obliged to throw away the original raw counts. Whether software can handle? The motivation for having a reduced dataset is to have data format that is transferable between softwares. But have you thrown too much at some point?

/Using SANS software

2026-04-07T07:41:48Z

Annikastellhorn:

Overview:
* Regarding BornAgain:
** Need a set of prototype models (check what is on the BA webpage) - especially for inexperienced users
** This should include a very detailed description about its physical limitations, directly implemented into BA sending error messages if overgone.
** Further good features to implement: (i) intensity w.r.t. direct beam, w.r.t multiple scattering background, w.r.t. general expected background (according to experience + commissioning).

Detailed notes group 4:
* A set of prototype models for several example systems is really great piece of help for inexperienced users of BornAgain.
* However, it will be even more helpful if every model describes its physical limitations - in other words, a user should be warned if he is choosing a value of a parameter which breaks the validity of the theory behind this model (for example size of the particles, particle distribution over the surface etc). So that a user do not consider unrealistic models.
* On the top of this it will be nice if a user can estimate
** intensity of GISANS signal in respect to the direct beam
** in respect to the multiple scattering background calculated by BornAgain
** in respect to a general background expected in the experiment (basing on the previous experience with similar sample environment, materials, guide halls etc).

* Sample environment should be continuously developed the knowledge is shared inside of the community.

Detailed notes group (?):
* Get inspiration from X-ray software:
** Brookhaven, Ben Ocko
* SasView:
** SASview people can read data in, put different resolution functions, co-fit X-ray and neutron data. For SANS it works but For GISANS not.
* BornAgain:
** BornAgain does not have a good defined intermediate format. The challenge is to get it to do fitting rather than simulation. Peaks at the right position is simple, getting right intensities is more complicated. Pictures can look similar but not fit in reality. Fitting in 2D is much harder than fitting in 1D. Few people do it in general. Even reflectivity X-ray and neutron is much more advanced in combined view. But with GISANS it is much more difficult. X-ray industry e.g. XENOCS will sell a GI stage and a software package which will give q xyz components but the fitting will be reduced to cuts (qz at particular q xy) so it is a quasi 1d fitting.
** Could collaborations like BA benefit from models defined by other software packages? E.g. Is there a form factor for this? Where can we find code for such form factors?
* Comparison BA and SasView:
** E.g. the structure of SASview is easy if you want to put a new form factor. Very few people do it. In the last 6 months there have been more people doing that but in general this is one of the problems, you don’t have many people who writes the plugins. What people do more, they combine modules or their own purposes. They are not of great generality, something might be written in a paper and people elaborate the code themselves. One has to learn fro other collaborations.
Interaction between BA and SASview? ICNS conference. Code camp in Garsching for SASview. No-one from Joachim’s group was participating. There could be something to see how a collaboration works.
* Regarding data reduction / data formats (repeated there):
** The package approach in BA might cause issues while SASview does not have them. Once the interface is defined it is hard to change it, same for the file format. One can design them to be extensible (NEXUS), to use new features. One has to think carefully what you insist people provide. For SAS data format, reflection format you need to provide certain information. The idea was that it can be extensible and if information is not provided it is simply skipped.
*** canSAS XML was developed for this. But people don’t use it in a right way, they don’t fill out the fields, data has incorrect format. It is not easy to solve these problems.
** The challenge with BA is that we don’t understand what is the input data. Originally was built around a monochromatic instrument with cartesian coordinates around the scattered beam. Strictly speaking SASview works in q space and it doesn’t assume anything about the detector space.
** One of the differences is how to make the software instrument independent. SASview: you provide reduced data where you have taken out all the instrument effects. The idea of q resolution without WL and angle, it can accommodate data from instruments with multiple detectors, you can concatenate them in one file.
** Before software for SAS used to compare errors if you have an area detector there are many pixels that goes to the same bin. What is the variation pix to pix in there. Statistics over the individual pixels is compared with the variation. One needs to have more information to test that. When it comes to model fitting you don’t trouble the fitting program with too complicated procedure at the moment. The peak fitting for diffraction already causes people a lot of problems. Once you try to correct for more things you get more uncertainties.
** With GISANS you re not obliged to throw away the original raw counts. Whether software can handle? The motivation for having a reduced dataset is to have data format that is transferable between softwares. But have you thrown too much at some point?

* Other:
** BoToSim and BoToFit.
** SpinW = software, neutron spinwave. It is Lucas Wilkins’ development in collaboration with another person.

/Multiple Scattering

2026-04-07T07:31:55Z

Annikastellhorn:

/Background handling

2026-04-07T07:27:30Z

Annikastellhorn:

Short overview from discussions/breakouts:
* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

Notes:
* How do you know which type of (multiple coh/incoh.) scattering exists? And then which model for background to use accordingly? Are there approximations?
* always use multiple terms of the DWBA approximation? Where to draw the boundary?
* should we aim at always including a ray tracing approach (like McStas) to consider multiple scattering effects? (see union components McStas): https://mads-bertelsen.github.io/tutorial/Union_tutorial_1_processes_and_materials.html
* this all would strongly affect fitting of GISANS - we guess that this is one reason that no fitting of GISANS exists at the moment?
* typical approach of subtracting background doesnt work if it comes from "the sample itself, i.e., by multiple scattering in the sample"
* can this be "tested" how much the sample affects the background, are there test samples for comparison?
* why not the "typical approach": you subtract the instrument background (has to be well known), and all other "background" has to be from the sample and has to be simulated/fitted? this has then to be known for all wavelength bands and incident angles
* comparison to QENS where signals are always weak - how is that handled? Can what is known from there be taken over? QENS: Start with approximations for the model, and this then has to be refined. Also there the precise knowledge of the sample and the estimations of multiple scattering involved have to be taken into account!
* measure multiple states / dispersions / other observables to decrease ratio (unkown parameters)/(measured parameters)
* how to judge if the simulation (even if fitting perfectly to the data) is the physical correct one? For the question of which parameters are influencing the cross section mostly using bayesian fitting: see papers from Josh (for reflectometry): https://journals.iucr.org/j/issues/2021/04/00/ge5096/ge5096sup1.pdf
* X-ray community:
** Grazing incidence background subtraction is very difficult already in the X-ray techniques. State of the art for X-ray techniques is looking for areas around the strong peaks. This solution is not optimal. You can’t put down the sample and so the best situation is to do the same experiment at a liquid-liquid interface with motion. Everything is in the same place, you put only the liquids in the same cell, GISAXS image with everything except the molecule which will be placed at the interface. Then make a new sample with the same position of the interface with an added molecule. The background sample has to be as close to the real sample as possible. = To have more information, not to be taken as the recipe for handling background.
** Surface scattering needs to be known to disentangle it from reflection.
* ToF aspects:
** Consider also ToF Background!
* How to acquire the Background:
** There is no general way to acquire data, many people do empirical background subtraction because there is no way to calculate it.
** Cut and put a polynomial under a peak without knowing what the polynomial is supposed to represent.

/GISANS - Advancing data reduction and analysis Workshop

2026-04-07T06:39:56Z

Annikastellhorn: /* Summary */

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides: To come
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
[[File:TopervergGISANS2026ILL1-part1.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 1]]
[[File:TopervergGISANS2026ILL1-part2.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
[[File:HF McStas.pdf|thumb|Introduction on McStas - Henrich Frielinghaus]]
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
[[File:Gutfreund OffSpec new part 1.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 1]]
[[File:Gutfreund OffSpec new part 2.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
[[File:Magnetic GISANS.pdf|thumb|Talk on "Magnetic and PA-GISANS" from Annika Stellhorn]]
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
Overall Summary

(i) ToF
* Instrument factors influence measurement strategies and tools are needed to aid this process.
* Background - effects of inelastic scattering can change background.
* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.
* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.
(ii) Multiple scattering
* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry
** They have to be identified before each experiment

(iii) Background handling
* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?
(iv) Normalization
* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed
(v) Using SANS software
* Regarding BornAgain:
** Need a set of prototype models (check what is on the BA webpage) - especially for inexperienced users
** This should include a very detailed description about its physical limitations, directly implemented into BA sending error messages if overgone.
** Further good features to implement: (i) intensity w.r.t. direct beam, w.r.t multiple scattering background, w.r.t. general expected background (according to experience + commissioning).
(vi) Instrumentation
* Missing
(vii) Common data format
* Missing
* Missing
(ix) Magnetic Scattering]
* considering ".nxs" files and dimensions: A scan of everything/motor should be considered a dimension in the "nxs". It should not be restricted to 4 dimensions.
* On-the-fly polarization analysis: online corrections are good. But highest precision correction should be done at the end of the experiment before the users go home.
(x) Off-Specular
* Missing

==== Outlook ====
* Letter in "Neutron News"

/Using SANS software

2026-04-07T06:30:53Z

Annikastellhorn:

/Off-Specular Scattering

2026-04-07T06:22:32Z

Annikastellhorn: Created blank page

/Notes Data Reduction

2026-04-07T06:21:15Z

Annikastellhorn: Created blank page

/Computer simulations / AI support

2026-04-07T06:20:29Z

Annikastellhorn: Created blank page

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-04-06T13:47:15Z

Annikastellhorn:

/GISANS - Advancing data reduction and analysis Workshop

2026-04-06T13:46:59Z

Annikastellhorn: Created page with "Workshop programme ==== Discussion session notes ==== '''POINT A. ToF-GISANS''' * Presentation slides: To come * Further Notes from the ILL-Workshop on: /ToF-GISANS '''POINT B. Multiple scattering''' * Presentation slides: thumb * Further Notes from the ILL-Workshop on: /Multiple Scattering '''POINT C. Background handling''' * Presentation slides: File:Background idea..."

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-04-06T13:45:51Z

Annikastellhorn:

=== Overview ===
'''GISANS Data Reduction and Analysis Upgrades Initiative:''' 
An initiative on “GISANS data reduction and analysis upgrades” was launched at the GISAXS-25 meeting in Hamburg in November 2025. The objective of the initiative is to develop a generic, instrument-independent software framework for GISANS data reduction and analysis that can be used across neutron research facilities.

'''Approach:''' 
The proposal is to build upon the open-source software package BornAgain and to identify and define the key developments required for broader GISANS usability. Planned areas of improvement include:
* more flexible treatment of instrument resolution,
* improved background subtraction,
* clearer approaches to normalization,
* increased interoperability with existing analysis and reduction software tools.

'''Planned Work:''' 
A dedicated working group has to be established with two primary tasks:
1. Defining a roadmap and priority list for the required functionality.
2. Implementing these features in collaboration with the BornAgain core development team. Contributions may include code development, example scripts, and other shared resources.

'''Next Steps:''' 
The GISANS community is being invited to participate in the initiative. A first workshop is planned for the first half of 2026, with Institut Laue-Langevin (ILL) proposed as the host venue. The meeting is intended to be held on-site, with the option for remote attendance.

=== Online Meeting 2025-11-13 ===

'''Participants:''' 
Adrian Rennie (Uppsala Univ.), Apostolos Vagias, Annika Stellhorn (ESS), Dirk Honecker (STFC-ISIS), Artur Glavic (PSI), Sebastian Jaksch (ESS). 
BornAgain team: Joachim Wuttke, Mikhail Svechnikov, Ammar Nejati. 
SAGA Team: Tom Arnold, Tommy Nylander, Max Wolff, Milan Klausz. 

'''Date:''' 
13th November 2025

'''Content:''' 
1. Introduction (Annika) 
2. Current activites in BornAgain (BA) (Joachim Wuttke) 
3. “Quick” Roadmap discussion 
4. Preparation of on-site meeting at ILL 
5. “How-to” 

====Introduction (Annika)====
* Goal: Getting an instrument-independent GISANS software
* Question: (For using BornAgain as such) How to make it attractive for more users? How to implement together more features?
* Answers: Most important to (i) define most necessary items, (ii) keep it simple, (iii) have a core developers team (the current BA-team), that (iv) gets help by python/C++-code contributions by the community – e.g. into a separate repository that will be reviewed by the core team
* Next steps: 2-3 days in-person meeting. Current idea: at ILL. Contributors: from each neutron source (experimentalists + data scientists) + the GISAS core users.

====Current activities in BornAgain (BA) (Joachim Wuttke)====
* BA is an open-source software, everyone can access and contribute
* Idea: Make it simpler, cleaner, more accessible, in the best case community-maintained to get a long-term manageable project
* Nearly everything is possible from Python interface, but not from the GUI.
* The GUI shall not be altered too much for the next coming years
* Plans: First achieving simplification, afterwards working on extensions
* Current biggest challenge: handling of coherent vs. incoherent scattering contributions
* Next goals: Auto-generation of new geometric shapes

====Preparation of On-site meeting at ILL====
* Aim at first half of 2026
* Ask for (i) core-team dates, (ii) community dates

====“Quick” Roadmap discussion====

'''POINT A.+B. ToF-GISANS + Multiple scattering''' 
* Possible in Python / via jupyter notebook in BA. Keep it there.
* Computationally heavy: has to be inserted into BA via slicing it down to monochromatic slices with individual resolution functions
* Needs to be done via ROI-definition
* Complicated for users:
** especially due to complicated connection to multiple scattering & incoherent scattering
** different backgrounds for different lambda/incident angles which is additionally dominated by multiple scattering
* Need to differentiate between: (i) incoherent multiple scattering, (ii) multiple scattering for which Born approximation breaks down

'''POINT C. Background handling''' 
* A challenge for weakly scattering systems
* Connected to points (A) + (B).
* Challenging case of angular-dependent “incoherent multiple scattering” in many soft matter systems
* The generic question “how do we subtract bkg?” becomes relevant as well
* Again, computationally heavy/long. Possible solution: ROI-definition
* Existing user scripts that have proven to work, can be implemented into BA
* Influence from hydrogen?

'''POINT D. Normalization''' 
* In SAS, we put units of cm-1 (or sr-1).
* In reflectivity, data are normally reported as ratio to incident beam (flux or counts).
* In GISAS, not clear consensus as to how data are reported
* Correct background substraction and its impact on normalization and absolute intensity calculation has to be taken care of

'''POINT E. Using SANS software''' 
* For data analysis:
** Have the possibility to import missing form factors from e.g. SASView, SASfit?
** need a plug-in feature that is compatible with existing other software, e.g. via FabIO (Can it now read all detector formats into BornAgain?)
** Advancements of fitting procedures to 2d scattering patterns?
**. "Easy and quick" data analysis features like creating 1d cuts etc.?
* For data reduction:
** Needs to be compatible to existing software like GRASP or MANTID
** Key: well-defined .nxs (canSAS) standard

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Instrument-dependent aspects (more than 1 detector arrays with potentially useful and unexploited information, sample geometry, detector-background, polarization efficiency, error-bars) have to be reduced at the instrument as usual
* Calculation of resolution function in proper coordinate system --> can be tricky for non-experts.
* Important for implementation in BornAgain: Q/lambda resolution functions
** Can be implemented fast (via “Issue Tracker” of BornAgain?)
** Best to start from working/existing models
* Polarization-dependent 4-channel calculation could be a pre-defined python script to make it easier for beginners
* GISAXS community might be interested in joining the discussion on resolution functions
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 

* To be contributed via “requests”/”patches” to the documentation sources.

'''POINT H. Integration of McStas with BornAgain''' 
* Feedback-loops available (from Artur) between McStas and BornAgain, but no fitting possible

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Making use of canSAS and ORSO standards
* Need to extend both the canSAS/ORSO formats towards GISAS

====“How-to”====
* Keep BA-group as core developers group. Contributions by the community on most urgent items
* have a section on BornAgain source/repository (called contributions). People can put contributions there, not mixing with main core. This does not interfere with complicated C++ core of BornAgain, but would benefit from Python scripts.
* Distribution of notes / goals / etc. + Conversation via cansas
** Need to re-populate and extend the cansas wiki for GISANS
* Occasional in-person workshops, first one at ILL first half of 2026 (aim at max ca. 40 people. Aim that each facility cover the travel costs of the participating individuals?)
** Goal: Extending the roadmap + defining a priority list
** If possible, connection to another event would be appreciated – otherwise we organize it independently
** Partial financing of meeting by SAGA team possible for ca. 10 people
** Making online attendance possible
** If possible, including an overview of current status from BornAgain to all participants
* Further Notes from the ILL-Workshop on: [[/Notes How to go forward]]

=== First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 ===

A first workshop with the international GISA(X/N)S community has been hold in Grenoble on the 17th-18th of March 2026 in hybrid mode. The workshop overview, discussion points, presentation slides, and a summary can be found here:
[[/GISANS - Advancing data reduction and analysis Workshop #1" 2026-03-17/18]]

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides: To come
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
[[File:TopervergGISANS2026ILL1-part1.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 1]]
[[File:TopervergGISANS2026ILL1-part2.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
[[File:HF McStas.pdf|thumb|Introduction on McStas - Henrich Frielinghaus]]
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
[[File:Gutfreund OffSpec new part 1.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 1]]
[[File:Gutfreund OffSpec new part 2.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
[[File:Magnetic GISANS.pdf|thumb|Talk on "Magnetic and PA-GISANS" from Annika Stellhorn]]
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
* Instrument factors influence measurement strategies and tools are needed to aid this process.

* Background - effects of inelastic scattering can change background.

* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.

* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.

* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry

* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed

==== Outlook ====
* Letter in "Neutron News"

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-04-06T13:41:09Z

Annikastellhorn:

=== Overview ===
'''GISANS Data Reduction and Analysis Upgrades Initiative:''' 
An initiative on “GISANS data reduction and analysis upgrades” was launched at the GISAXS-25 meeting in Hamburg in November 2025. The objective of the initiative is to develop a generic, instrument-independent software framework for GISANS data reduction and analysis that can be used across neutron research facilities.

'''Approach:''' 
The proposal is to build upon the open-source software package BornAgain and to identify and define the key developments required for broader GISANS usability. Planned areas of improvement include:
* more flexible treatment of instrument resolution,
* improved background subtraction,
* clearer approaches to normalization,
* increased interoperability with existing analysis and reduction software tools.

'''Planned Work:''' 
A dedicated working group has to be established with two primary tasks:
1. Defining a roadmap and priority list for the required functionality.
2. Implementing these features in collaboration with the BornAgain core development team. Contributions may include code development, example scripts, and other shared resources.

'''Next Steps:''' 
The GISANS community is being invited to participate in the initiative. A first workshop is planned for the first half of 2026, with Institut Laue-Langevin (ILL) proposed as the host venue. The meeting is intended to be held on-site, with the option for remote attendance.

=== Online Meeting 2025-11-13 ===

'''Participants:''' 
Adrian Rennie (Uppsala Univ.), Apostolos Vagias, Annika Stellhorn (ESS), Dirk Honecker (STFC-ISIS), Artur Glavic (PSI), Sebastian Jaksch (ESS). 
BornAgain team: Joachim Wuttke, Mikhail Svechnikov, Ammar Nejati. 
SAGA Team: Tom Arnold, Tommy Nylander, Max Wolff, Milan Klausz. 

'''Date:''' 
13th November 2025

'''Content:''' 
1. Introduction (Annika) 
2. Current activites in BornAgain (BA) (Joachim Wuttke) 
3. “Quick” Roadmap discussion 
4. Preparation of on-site meeting at ILL 
5. “How-to” 

====Introduction (Annika)====
* Goal: Getting an instrument-independent GISANS software
* Question: (For using BornAgain as such) How to make it attractive for more users? How to implement together more features?
* Answers: Most important to (i) define most necessary items, (ii) keep it simple, (iii) have a core developers team (the current BA-team), that (iv) gets help by python/C++-code contributions by the community – e.g. into a separate repository that will be reviewed by the core team
* Next steps: 2-3 days in-person meeting. Current idea: at ILL. Contributors: from each neutron source (experimentalists + data scientists) + the GISAS core users.

====Current activities in BornAgain (BA) (Joachim Wuttke)====
* BA is an open-source software, everyone can access and contribute
* Idea: Make it simpler, cleaner, more accessible, in the best case community-maintained to get a long-term manageable project
* Nearly everything is possible from Python interface, but not from the GUI.
* The GUI shall not be altered too much for the next coming years
* Plans: First achieving simplification, afterwards working on extensions
* Current biggest challenge: handling of coherent vs. incoherent scattering contributions
* Next goals: Auto-generation of new geometric shapes

====Preparation of On-site meeting at ILL====
* Aim at first half of 2026
* Ask for (i) core-team dates, (ii) community dates

====“Quick” Roadmap discussion====

'''POINT A.+B. ToF-GISANS + Multiple scattering''' 
* Possible in Python / via jupyter notebook in BA. Keep it there.
* Computationally heavy: has to be inserted into BA via slicing it down to monochromatic slices with individual resolution functions
* Needs to be done via ROI-definition
* Complicated for users:
** especially due to complicated connection to multiple scattering & incoherent scattering
** different backgrounds for different lambda/incident angles which is additionally dominated by multiple scattering
* Need to differentiate between: (i) incoherent multiple scattering, (ii) multiple scattering for which Born approximation breaks down
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* A challenge for weakly scattering systems
* Connected to points (A) + (B).
* Challenging case of angular-dependent “incoherent multiple scattering” in many soft matter systems
* The generic question “how do we subtract bkg?” becomes relevant as well
* Again, computationally heavy/long. Possible solution: ROI-definition
* Existing user scripts that have proven to work, can be implemented into BA
* Influence from hydrogen?
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* In SAS, we put units of cm-1 (or sr-1).
* In reflectivity, data are normally reported as ratio to incident beam (flux or counts).
* In GISAS, not clear consensus as to how data are reported
* Correct background substraction and its impact on normalization and absolute intensity calculation has to be taken care of
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* For data analysis:
** Have the possibility to import missing form factors from e.g. SASView, SASfit?
** need a plug-in feature that is compatible with existing other software, e.g. via FabIO (Can it now read all detector formats into BornAgain?)
** Advancements of fitting procedures to 2d scattering patterns?
**. "Easy and quick" data analysis features like creating 1d cuts etc.?
* For data reduction:
** Needs to be compatible to existing software like GRASP or MANTID
** Key: well-defined .nxs (canSAS) standard
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Instrument-dependent aspects (more than 1 detector arrays with potentially useful and unexploited information, sample geometry, detector-background, polarization efficiency, error-bars) have to be reduced at the instrument as usual
* Calculation of resolution function in proper coordinate system --> can be tricky for non-experts.
* Important for implementation in BornAgain: Q/lambda resolution functions
** Can be implemented fast (via “Issue Tracker” of BornAgain?)
** Best to start from working/existing models
* Polarization-dependent 4-channel calculation could be a pre-defined python script to make it easier for beginners
* GISAXS community might be interested in joining the discussion on resolution functions
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 

* To be contributed via “requests”/”patches” to the documentation sources.
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Feedback-loops available (from Artur) between McStas and BornAgain, but no fitting possible
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Making use of canSAS and ORSO standards
* Need to extend both the canSAS/ORSO formats towards GISAS
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 

* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

====“How-to”====
* Keep BA-group as core developers group. Contributions by the community on most urgent items
* have a section on BornAgain source/repository (called contributions). People can put contributions there, not mixing with main core. This does not interfere with complicated C++ core of BornAgain, but would benefit from Python scripts.
* Distribution of notes / goals / etc. + Conversation via cansas
** Need to re-populate and extend the cansas wiki for GISANS
* Occasional in-person workshops, first one at ILL first half of 2026 (aim at max ca. 40 people. Aim that each facility cover the travel costs of the participating individuals?)
** Goal: Extending the roadmap + defining a priority list
** If possible, connection to another event would be appreciated – otherwise we organize it independently
** Partial financing of meeting by SAGA team possible for ca. 10 people
** Making online attendance possible
** If possible, including an overview of current status from BornAgain to all participants
* Further Notes from the ILL-Workshop on: [[/Notes How to go forward]]

=== First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 ===

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
[[File:TopervergGISANS2026ILL1-part1.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 1]]
[[File:TopervergGISANS2026ILL1-part2.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
[[File:HF McStas.pdf|thumb|Introduction on McStas - Henrich Frielinghaus]]
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
[[File:Gutfreund OffSpec new part 1.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 1]]
[[File:Gutfreund OffSpec new part 2.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
[[File:Magnetic GISANS.pdf|thumb|Talk on "Magnetic and PA-GISANS" from Annika Stellhorn]]
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
* Instrument factors influence measurement strategies and tools are needed to aid this process.

* Background - effects of inelastic scattering can change background.

* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.

* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.

* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry

* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed

==== Outlook ====
* Letter in "Neutron News"

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-04-06T13:38:24Z

Annikastellhorn:

=== Overview ===
'''GISANS Data Reduction and Analysis Upgrades Initiative:''' 
An initiative on “GISANS data reduction and analysis upgrades” was launched at the GISAXS-25 meeting in Hamburg in November 2025. The objective of the initiative is to develop a generic, instrument-independent software framework for GISANS data reduction and analysis that can be used across neutron research facilities.

'''Approach:''' 
The proposal is to build upon the open-source software package BornAgain and to identify and define the key developments required for broader GISANS usability. Planned areas of improvement include:
* more flexible treatment of instrument resolution,
* improved background subtraction,
* clearer approaches to normalization,
* increased interoperability with existing analysis and reduction software tools.

'''Planned Work:''' 
A dedicated working group has to be established with two primary tasks:
1. Defining a roadmap and priority list for the required functionality.
2. Implementing these features in collaboration with the BornAgain core development team. Contributions may include code development, example scripts, and other shared resources.

'''Next Steps:''' 
The GISANS community is being invited to participate in the initiative. A first workshop is planned for the first half of 2026, with Institut Laue-Langevin (ILL) proposed as the host venue. The meeting is intended to be held on-site, with the option for remote attendance.

=== Online Meeting 2025-11-13 ===

'''Participants:''' 
Adrian Rennie (Uppsala Univ.), Apostolos Vagias, Annika Stellhorn (ESS), Dirk Honecker (STFC-ISIS), Artur Glavic (PSI), Sebastian Jaksch (ESS). 
BornAgain team: Joachim Wuttke, Mikhail Svechnikov, Ammar Nejati. 
SAGA Team: Tom Arnold, Tommy Nylander, Max Wolff, Milan Klausz. 

'''Date:''' 
13th November 2025

'''Content:''' 
1. Introduction (Annika) 
2. Current activites in BornAgain (BA) (Joachim Wuttke) 
3. “Quick” Roadmap discussion 
4. Preparation of on-site meeting at ILL 
5. “How-to” 

====Introduction (Annika)====
* Goal: Getting an instrument-independent GISANS software
* Question: (For using BornAgain as such) How to make it attractive for more users? How to implement together more features?
* Answers: Most important to (i) define most necessary items, (ii) keep it simple, (iii) have a core developers team (the current BA-team), that (iv) gets help by python/C++-code contributions by the community – e.g. into a separate repository that will be reviewed by the core team
* Next steps: 2-3 days in-person meeting. Current idea: at ILL. Contributors: from each neutron source (experimentalists + data scientists) + the GISAS core users.

====Current activities in BornAgain (BA) (Joachim Wuttke)====
* BA is an open-source software, everyone can access and contribute
* Idea: Make it simpler, cleaner, more accessible, in the best case community-maintained to get a long-term manageable project
* Nearly everything is possible from Python interface, but not from the GUI.
* The GUI shall not be altered too much for the next coming years
* Plans: First achieving simplification, afterwards working on extensions
* Current biggest challenge: handling of coherent vs. incoherent scattering contributions
* Next goals: Auto-generation of new geometric shapes

====Preparation of On-site meeting at ILL====
* Aim at first half of 2026
* Ask for (i) core-team dates, (ii) community dates

====“Quick” Roadmap discussion====

'''POINT A.+B. ToF-GISANS + Multiple scattering''' 
* Possible in Python / via jupyter notebook in BA. Keep it there.
* Computationally heavy: has to be inserted into BA via slicing it down to monochromatic slices with individual resolution functions
* Needs to be done via ROI-definition
* Complicated for users:
** especially due to complicated connection to multiple scattering & incoherent scattering
** different backgrounds for different lambda/incident angles which is additionally dominated by multiple scattering
* Need to differentiate between: (i) incoherent multiple scattering, (ii) multiple scattering for which Born approximation breaks down
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* A challenge for weakly scattering systems
* Connected to points (A) + (B).
* Challenging case of angular-dependent “incoherent multiple scattering” in many soft matter systems
* The generic question “how do we subtract bkg?” becomes relevant as well
* Again, computationally heavy/long. Possible solution: ROI-definition
* Existing user scripts that have proven to work, can be implemented into BA
* Influence from hydrogen?
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* In SAS, we put units of cm-1 (or sr-1).
* In reflectivity, data are normally reported as ratio to incident beam (flux or counts).
* In GISAS, not clear consensus as to how data are reported
* Correct background substraction and its impact on normalization and absolute intensity calculation has to be taken care of
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* For data analysis:
** Have the possibility to import missing form factors from e.g. SASView, SASfit?
** need a plug-in feature that is compatible with existing other software, e.g. via FabIO (Can it now read all detector formats into BornAgain?)
** Advancements of fitting procedures to 2d scattering patterns?
**. "Easy and quick" data analysis features like creating 1d cuts etc.?
* For data reduction:
** Needs to be compatible to existing software like GRASP or MANTID
** Key: well-defined .nxs (canSAS) standard
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Instrument-dependent aspects (more than 1 detector arrays with potentially useful and unexploited information, sample geometry, detector-background, polarization efficiency, error-bars) have to be reduced at the instrument as usual
* Calculation of resolution function in proper coordinate system --> can be tricky for non-experts.
* Important for implementation in BornAgain: Q/lambda resolution functions
** Can be implemented fast (via “Issue Tracker” of BornAgain?)
** Best to start from working/existing models
* Polarization-dependent 4-channel calculation could be a pre-defined python script to make it easier for beginners
* GISAXS community might be interested in joining the discussion on resolution functions
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 

* To be contributed via “requests”/”patches” to the documentation sources.
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Feedback-loops available (from Artur) between McStas and BornAgain, but no fitting possible
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Making use of canSAS and ORSO standards
* Need to extend both the canSAS/ORSO formats towards GISAS
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 

* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

====“How-to”====
* Keep BA-group as core developers group. Contributions by the community on most urgent items
* have a section on BornAgain source/repository (called contributions). People can put contributions there, not mixing with main core. This does not interfere with complicated C++ core of BornAgain, but would benefit from Python scripts.
* Distribution of notes / goals / etc. + Conversation via cansas
** Need to re-populate and extend the cansas wiki for GISANS
* Occasional in-person workshops, first one at ILL first half of 2026 (aim at max ca. 40 people. Aim that each facility cover the travel costs of the participating individuals?)
** Goal: Extending the roadmap + defining a priority list
** If possible, connection to another event would be appreciated – otherwise we organize it independently
** Partial financing of meeting by SAGA team possible for ca. 10 people
** Making online attendance possible
** If possible, including an overview of current status from BornAgain to all participants
* Further Notes from the ILL-Workshop on: [[/Notes How to go forward]]

=== First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 ===

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
[[File:TopervergGISANS2026ILL1-part1.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 1]]
[[File:TopervergGISANS2026ILL1-part2.pdf|thumb|Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 2]]
* Add slides from Boris Toperverg: check what to do when file too big
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
[[File:HF McStas.pdf|thumb|Introduction on McStas - Henrich Frielinghaus]]
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
[[File:Gutfreund OffSpec new part 1.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 1]]
[[File:Gutfreund OffSpec new part 2.pdf|thumb|Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 2]]
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
[[File:Magnetic GISANS.pdf|thumb|Talk on "Magnetic and PA-GISANS" from Annika Stellhorn]]
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
* Instrument factors influence measurement strategies and tools are needed to aid this process.

* Background - effects of inelastic scattering can change background.

* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.

* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.

* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry

* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed

==== Outlook ====
* Letter in "Neutron News"

File:Magnetic GISANS.pdf

2026-04-06T13:38:05Z

Annikastellhorn:

Talk on "Magnetic and PA-GISANS" from Annika Stellhorn

File:Gutfreund OffSpec new part 2.pdf

2026-04-06T13:36:12Z

Annikastellhorn:

Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 2

File:Gutfreund OffSpec new part 1.pdf

2026-04-06T13:35:50Z

Annikastellhorn:

Talk on "Offspecular Scattering" from Philipp Gutfreund - Part 1

File:TopervergGISANS2026ILL1-part2.pdf

2026-04-06T13:30:40Z

Annikastellhorn:

Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 2

File:TopervergGISANS2026ILL1-part1.pdf

2026-04-06T13:30:16Z

Annikastellhorn:

Talk "DWBA: kinematics, coherence & resolution issues" from Boris Toperverg - Part 1

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-03-25T15:51:34Z

Annikastellhorn: /* First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 */

=== Overview ===
'''GISANS Data Reduction and Analysis Upgrades Initiative:''' 
An initiative on “GISANS data reduction and analysis upgrades” was launched at the GISAXS-25 meeting in Hamburg in November 2025. The objective of the initiative is to develop a generic, instrument-independent software framework for GISANS data reduction and analysis that can be used across neutron research facilities.

'''Approach:''' 
The proposal is to build upon the open-source software package BornAgain and to identify and define the key developments required for broader GISANS usability. Planned areas of improvement include:
* more flexible treatment of instrument resolution,
* improved background subtraction,
* clearer approaches to normalization,
* increased interoperability with existing analysis and reduction software tools.

'''Planned Work:''' 
A dedicated working group has to be established with two primary tasks:
1. Defining a roadmap and priority list for the required functionality.
2. Implementing these features in collaboration with the BornAgain core development team. Contributions may include code development, example scripts, and other shared resources.

'''Next Steps:''' 
The GISANS community is being invited to participate in the initiative. A first workshop is planned for the first half of 2026, with Institut Laue-Langevin (ILL) proposed as the host venue. The meeting is intended to be held on-site, with the option for remote attendance.

=== Online Meeting 2025-11-13 ===

'''Participants:''' 
Adrian Rennie (Uppsala Univ.), Apostolos Vagias, Annika Stellhorn (ESS), Dirk Honecker (STFC-ISIS), Artur Glavic (PSI), Sebastian Jaksch (ESS). 
BornAgain team: Joachim Wuttke, Mikhail Svechnikov, Ammar Nejati. 
SAGA Team: Tom Arnold, Tommy Nylander, Max Wolff, Milan Klausz. 

'''Date:''' 
13th November 2025

'''Content:''' 
1. Introduction (Annika) 
2. Current activites in BornAgain (BA) (Joachim Wuttke) 
3. “Quick” Roadmap discussion 
4. Preparation of on-site meeting at ILL 
5. “How-to” 

====Introduction (Annika)====
* Goal: Getting an instrument-independent GISANS software
* Question: (For using BornAgain as such) How to make it attractive for more users? How to implement together more features?
* Answers: Most important to (i) define most necessary items, (ii) keep it simple, (iii) have a core developers team (the current BA-team), that (iv) gets help by python/C++-code contributions by the community – e.g. into a separate repository that will be reviewed by the core team
* Next steps: 2-3 days in-person meeting. Current idea: at ILL. Contributors: from each neutron source (experimentalists + data scientists) + the GISAS core users.

====Current activities in BornAgain (BA) (Joachim Wuttke)====
* BA is an open-source software, everyone can access and contribute
* Idea: Make it simpler, cleaner, more accessible, in the best case community-maintained to get a long-term manageable project
* Nearly everything is possible from Python interface, but not from the GUI.
* The GUI shall not be altered too much for the next coming years
* Plans: First achieving simplification, afterwards working on extensions
* Current biggest challenge: handling of coherent vs. incoherent scattering contributions
* Next goals: Auto-generation of new geometric shapes

====Preparation of On-site meeting at ILL====
* Aim at first half of 2026
* Ask for (i) core-team dates, (ii) community dates

====“Quick” Roadmap discussion====

'''POINT A.+B. ToF-GISANS + Multiple scattering''' 
* Possible in Python / via jupyter notebook in BA. Keep it there.
* Computationally heavy: has to be inserted into BA via slicing it down to monochromatic slices with individual resolution functions
* Needs to be done via ROI-definition
* Complicated for users:
** especially due to complicated connection to multiple scattering & incoherent scattering
** different backgrounds for different lambda/incident angles which is additionally dominated by multiple scattering
* Need to differentiate between: (i) incoherent multiple scattering, (ii) multiple scattering for which Born approximation breaks down
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* A challenge for weakly scattering systems
* Connected to points (A) + (B).
* Challenging case of angular-dependent “incoherent multiple scattering” in many soft matter systems
* The generic question “how do we subtract bkg?” becomes relevant as well
* Again, computationally heavy/long. Possible solution: ROI-definition
* Existing user scripts that have proven to work, can be implemented into BA
* Influence from hydrogen?
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* In SAS, we put units of cm-1 (or sr-1).
* In reflectivity, data are normally reported as ratio to incident beam (flux or counts).
* In GISAS, not clear consensus as to how data are reported
* Correct background substraction and its impact on normalization and absolute intensity calculation has to be taken care of
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* For data analysis:
** Have the possibility to import missing form factors from e.g. SASView, SASfit?
** need a plug-in feature that is compatible with existing other software, e.g. via FabIO (Can it now read all detector formats into BornAgain?)
** Advancements of fitting procedures to 2d scattering patterns?
**. "Easy and quick" data analysis features like creating 1d cuts etc.?
* For data reduction:
** Needs to be compatible to existing software like GRASP or MANTID
** Key: well-defined .nxs (canSAS) standard
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Instrument-dependent aspects (more than 1 detector arrays with potentially useful and unexploited information, sample geometry, detector-background, polarization efficiency, error-bars) have to be reduced at the instrument as usual
* Calculation of resolution function in proper coordinate system --> can be tricky for non-experts.
* Important for implementation in BornAgain: Q/lambda resolution functions
** Can be implemented fast (via “Issue Tracker” of BornAgain?)
** Best to start from working/existing models
* Polarization-dependent 4-channel calculation could be a pre-defined python script to make it easier for beginners
* GISAXS community might be interested in joining the discussion on resolution functions
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 

* To be contributed via “requests”/”patches” to the documentation sources.
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Feedback-loops available (from Artur) between McStas and BornAgain, but no fitting possible
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Making use of canSAS and ORSO standards
* Need to extend both the canSAS/ORSO formats towards GISAS
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 

* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

====“How-to”====
* Keep BA-group as core developers group. Contributions by the community on most urgent items
* have a section on BornAgain source/repository (called contributions). People can put contributions there, not mixing with main core. This does not interfere with complicated C++ core of BornAgain, but would benefit from Python scripts.
* Distribution of notes / goals / etc. + Conversation via cansas
** Need to re-populate and extend the cansas wiki for GISANS
* Occasional in-person workshops, first one at ILL first half of 2026 (aim at max ca. 40 people. Aim that each facility cover the travel costs of the participating individuals?)
** Goal: Extending the roadmap + defining a priority list
** If possible, connection to another event would be appreciated – otherwise we organize it independently
** Partial financing of meeting by SAGA team possible for ca. 10 people
** Making online attendance possible
** If possible, including an overview of current status from BornAgain to all participants
* Further Notes from the ILL-Workshop on: [[/Notes How to go forward]]

=== First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 ===

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
* Add slides from Boris Toperverg: check what to do when file too big
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
[[File:HF McStas.pdf|thumb|Introduction on McStas - Henrich Frielinghaus]]
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* No Introduction talk
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
* Instrument factors influence measurement strategies and tools are needed to aid this process.

* Background - effects of inelastic scattering can change background.

* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.

* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.

* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry

* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed

==== Outlook ====
* Letter in "Neutron News"

File:HF McStas.pdf

2026-03-25T15:47:23Z

Annikastellhorn:

Introduction talk McStas - Henrich Frielinghaus

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-03-25T15:38:11Z

Annikastellhorn: /* Discussion session notes */

=== Overview ===
'''GISANS Data Reduction and Analysis Upgrades Initiative:''' 
An initiative on “GISANS data reduction and analysis upgrades” was launched at the GISAXS-25 meeting in Hamburg in November 2025. The objective of the initiative is to develop a generic, instrument-independent software framework for GISANS data reduction and analysis that can be used across neutron research facilities.

'''Approach:''' 
The proposal is to build upon the open-source software package BornAgain and to identify and define the key developments required for broader GISANS usability. Planned areas of improvement include:
* more flexible treatment of instrument resolution,
* improved background subtraction,
* clearer approaches to normalization,
* increased interoperability with existing analysis and reduction software tools.

'''Planned Work:''' 
A dedicated working group has to be established with two primary tasks:
1. Defining a roadmap and priority list for the required functionality.
2. Implementing these features in collaboration with the BornAgain core development team. Contributions may include code development, example scripts, and other shared resources.

'''Next Steps:''' 
The GISANS community is being invited to participate in the initiative. A first workshop is planned for the first half of 2026, with Institut Laue-Langevin (ILL) proposed as the host venue. The meeting is intended to be held on-site, with the option for remote attendance.

=== Online Meeting 2025-11-13 ===

'''Participants:''' 
Adrian Rennie (Uppsala Univ.), Apostolos Vagias, Annika Stellhorn (ESS), Dirk Honecker (STFC-ISIS), Artur Glavic (PSI), Sebastian Jaksch (ESS). 
BornAgain team: Joachim Wuttke, Mikhail Svechnikov, Ammar Nejati. 
SAGA Team: Tom Arnold, Tommy Nylander, Max Wolff, Milan Klausz. 

'''Date:''' 
13th November 2025

'''Content:''' 
1. Introduction (Annika) 
2. Current activites in BornAgain (BA) (Joachim Wuttke) 
3. “Quick” Roadmap discussion 
4. Preparation of on-site meeting at ILL 
5. “How-to” 

====Introduction (Annika)====
* Goal: Getting an instrument-independent GISANS software
* Question: (For using BornAgain as such) How to make it attractive for more users? How to implement together more features?
* Answers: Most important to (i) define most necessary items, (ii) keep it simple, (iii) have a core developers team (the current BA-team), that (iv) gets help by python/C++-code contributions by the community – e.g. into a separate repository that will be reviewed by the core team
* Next steps: 2-3 days in-person meeting. Current idea: at ILL. Contributors: from each neutron source (experimentalists + data scientists) + the GISAS core users.

====Current activities in BornAgain (BA) (Joachim Wuttke)====
* BA is an open-source software, everyone can access and contribute
* Idea: Make it simpler, cleaner, more accessible, in the best case community-maintained to get a long-term manageable project
* Nearly everything is possible from Python interface, but not from the GUI.
* The GUI shall not be altered too much for the next coming years
* Plans: First achieving simplification, afterwards working on extensions
* Current biggest challenge: handling of coherent vs. incoherent scattering contributions
* Next goals: Auto-generation of new geometric shapes

====Preparation of On-site meeting at ILL====
* Aim at first half of 2026
* Ask for (i) core-team dates, (ii) community dates

====“Quick” Roadmap discussion====

'''POINT A.+B. ToF-GISANS + Multiple scattering''' 
* Possible in Python / via jupyter notebook in BA. Keep it there.
* Computationally heavy: has to be inserted into BA via slicing it down to monochromatic slices with individual resolution functions
* Needs to be done via ROI-definition
* Complicated for users:
** especially due to complicated connection to multiple scattering & incoherent scattering
** different backgrounds for different lambda/incident angles which is additionally dominated by multiple scattering
* Need to differentiate between: (i) incoherent multiple scattering, (ii) multiple scattering for which Born approximation breaks down
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* A challenge for weakly scattering systems
* Connected to points (A) + (B).
* Challenging case of angular-dependent “incoherent multiple scattering” in many soft matter systems
* The generic question “how do we subtract bkg?” becomes relevant as well
* Again, computationally heavy/long. Possible solution: ROI-definition
* Existing user scripts that have proven to work, can be implemented into BA
* Influence from hydrogen?
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* In SAS, we put units of cm-1 (or sr-1).
* In reflectivity, data are normally reported as ratio to incident beam (flux or counts).
* In GISAS, not clear consensus as to how data are reported
* Correct background substraction and its impact on normalization and absolute intensity calculation has to be taken care of
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* For data analysis:
** Have the possibility to import missing form factors from e.g. SASView, SASfit?
** need a plug-in feature that is compatible with existing other software, e.g. via FabIO (Can it now read all detector formats into BornAgain?)
** Advancements of fitting procedures to 2d scattering patterns?
**. "Easy and quick" data analysis features like creating 1d cuts etc.?
* For data reduction:
** Needs to be compatible to existing software like GRASP or MANTID
** Key: well-defined .nxs (canSAS) standard
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Instrument-dependent aspects (more than 1 detector arrays with potentially useful and unexploited information, sample geometry, detector-background, polarization efficiency, error-bars) have to be reduced at the instrument as usual
* Calculation of resolution function in proper coordinate system --> can be tricky for non-experts.
* Important for implementation in BornAgain: Q/lambda resolution functions
** Can be implemented fast (via “Issue Tracker” of BornAgain?)
** Best to start from working/existing models
* Polarization-dependent 4-channel calculation could be a pre-defined python script to make it easier for beginners
* GISAXS community might be interested in joining the discussion on resolution functions
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 

* To be contributed via “requests”/”patches” to the documentation sources.
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Feedback-loops available (from Artur) between McStas and BornAgain, but no fitting possible
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Making use of canSAS and ORSO standards
* Need to extend both the canSAS/ORSO formats towards GISAS
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 

* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

====“How-to”====
* Keep BA-group as core developers group. Contributions by the community on most urgent items
* have a section on BornAgain source/repository (called contributions). People can put contributions there, not mixing with main core. This does not interfere with complicated C++ core of BornAgain, but would benefit from Python scripts.
* Distribution of notes / goals / etc. + Conversation via cansas
** Need to re-populate and extend the cansas wiki for GISANS
* Occasional in-person workshops, first one at ILL first half of 2026 (aim at max ca. 40 people. Aim that each facility cover the travel costs of the participating individuals?)
** Goal: Extending the roadmap + defining a priority list
** If possible, connection to another event would be appreciated – otherwise we organize it independently
** Partial financing of meeting by SAGA team possible for ca. 10 people
** Making online attendance possible
** If possible, including an overview of current status from BornAgain to all participants
* Further Notes from the ILL-Workshop on: [[/Notes How to go forward]]

=== First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 ===

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
[[File:GISANS-NormalizationDiscussionStarters.pdf|thumb|Introduction to Normalization - Sebastian Jaksch]]
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* No introduction talk
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf|thumb|Introduction to ToF Resolution aspects - Jean-Francois Moulin]]
* Add slides from Boris Toperverg: check what to do when file too big
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* Presentation slides:

* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
[[File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf|thumb|Introduction to ToF Data Reduction - Jean-Francois Moulin]]
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
* Instrument factors influence measurement strategies and tools are needed to aid this process.

* Background - effects of inelastic scattering can change background.

* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.

* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.

* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry

* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed

==== Outlook ====
* Letter in "Neutron News"

File:2026 03 CANSAS Grenoble Data Reduction TOF JFMoulin.pdf

2026-03-25T15:34:59Z

Annikastellhorn:

Introduction to ToF data reduction - Jean-Francois Moulin

File:2026 03 CANSAS Grenoble Resol Fn JFMoulin.pdf

2026-03-25T15:33:12Z

Annikastellhorn:

Introduction to ToF Resolution aspects - Jean-Francois Moulin

File:GISANS-NormalizationDiscussionStarters.pdf

2026-03-25T15:30:58Z

Annikastellhorn:

Introduction to Normalization - Sebastian Jaksch

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-03-25T15:28:17Z

Annikastellhorn: /* First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 */

=== Overview ===
'''GISANS Data Reduction and Analysis Upgrades Initiative:''' 
An initiative on “GISANS data reduction and analysis upgrades” was launched at the GISAXS-25 meeting in Hamburg in November 2025. The objective of the initiative is to develop a generic, instrument-independent software framework for GISANS data reduction and analysis that can be used across neutron research facilities.

'''Approach:''' 
The proposal is to build upon the open-source software package BornAgain and to identify and define the key developments required for broader GISANS usability. Planned areas of improvement include:
* more flexible treatment of instrument resolution,
* improved background subtraction,
* clearer approaches to normalization,
* increased interoperability with existing analysis and reduction software tools.

'''Planned Work:''' 
A dedicated working group has to be established with two primary tasks:
1. Defining a roadmap and priority list for the required functionality.
2. Implementing these features in collaboration with the BornAgain core development team. Contributions may include code development, example scripts, and other shared resources.

'''Next Steps:''' 
The GISANS community is being invited to participate in the initiative. A first workshop is planned for the first half of 2026, with Institut Laue-Langevin (ILL) proposed as the host venue. The meeting is intended to be held on-site, with the option for remote attendance.

=== Online Meeting 2025-11-13 ===

'''Participants:''' 
Adrian Rennie (Uppsala Univ.), Apostolos Vagias, Annika Stellhorn (ESS), Dirk Honecker (STFC-ISIS), Artur Glavic (PSI), Sebastian Jaksch (ESS). 
BornAgain team: Joachim Wuttke, Mikhail Svechnikov, Ammar Nejati. 
SAGA Team: Tom Arnold, Tommy Nylander, Max Wolff, Milan Klausz. 

'''Date:''' 
13th November 2025

'''Content:''' 
1. Introduction (Annika) 
2. Current activites in BornAgain (BA) (Joachim Wuttke) 
3. “Quick” Roadmap discussion 
4. Preparation of on-site meeting at ILL 
5. “How-to” 

====Introduction (Annika)====
* Goal: Getting an instrument-independent GISANS software
* Question: (For using BornAgain as such) How to make it attractive for more users? How to implement together more features?
* Answers: Most important to (i) define most necessary items, (ii) keep it simple, (iii) have a core developers team (the current BA-team), that (iv) gets help by python/C++-code contributions by the community – e.g. into a separate repository that will be reviewed by the core team
* Next steps: 2-3 days in-person meeting. Current idea: at ILL. Contributors: from each neutron source (experimentalists + data scientists) + the GISAS core users.

====Current activities in BornAgain (BA) (Joachim Wuttke)====
* BA is an open-source software, everyone can access and contribute
* Idea: Make it simpler, cleaner, more accessible, in the best case community-maintained to get a long-term manageable project
* Nearly everything is possible from Python interface, but not from the GUI.
* The GUI shall not be altered too much for the next coming years
* Plans: First achieving simplification, afterwards working on extensions
* Current biggest challenge: handling of coherent vs. incoherent scattering contributions
* Next goals: Auto-generation of new geometric shapes

====Preparation of On-site meeting at ILL====
* Aim at first half of 2026
* Ask for (i) core-team dates, (ii) community dates

====“Quick” Roadmap discussion====

'''POINT A.+B. ToF-GISANS + Multiple scattering''' 
* Possible in Python / via jupyter notebook in BA. Keep it there.
* Computationally heavy: has to be inserted into BA via slicing it down to monochromatic slices with individual resolution functions
* Needs to be done via ROI-definition
* Complicated for users:
** especially due to complicated connection to multiple scattering & incoherent scattering
** different backgrounds for different lambda/incident angles which is additionally dominated by multiple scattering
* Need to differentiate between: (i) incoherent multiple scattering, (ii) multiple scattering for which Born approximation breaks down
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* A challenge for weakly scattering systems
* Connected to points (A) + (B).
* Challenging case of angular-dependent “incoherent multiple scattering” in many soft matter systems
* The generic question “how do we subtract bkg?” becomes relevant as well
* Again, computationally heavy/long. Possible solution: ROI-definition
* Existing user scripts that have proven to work, can be implemented into BA
* Influence from hydrogen?
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* In SAS, we put units of cm-1 (or sr-1).
* In reflectivity, data are normally reported as ratio to incident beam (flux or counts).
* In GISAS, not clear consensus as to how data are reported
* Correct background substraction and its impact on normalization and absolute intensity calculation has to be taken care of
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* For data analysis:
** Have the possibility to import missing form factors from e.g. SASView, SASfit?
** need a plug-in feature that is compatible with existing other software, e.g. via FabIO (Can it now read all detector formats into BornAgain?)
** Advancements of fitting procedures to 2d scattering patterns?
**. "Easy and quick" data analysis features like creating 1d cuts etc.?
* For data reduction:
** Needs to be compatible to existing software like GRASP or MANTID
** Key: well-defined .nxs (canSAS) standard
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Instrument-dependent aspects (more than 1 detector arrays with potentially useful and unexploited information, sample geometry, detector-background, polarization efficiency, error-bars) have to be reduced at the instrument as usual
* Calculation of resolution function in proper coordinate system --> can be tricky for non-experts.
* Important for implementation in BornAgain: Q/lambda resolution functions
** Can be implemented fast (via “Issue Tracker” of BornAgain?)
** Best to start from working/existing models
* Polarization-dependent 4-channel calculation could be a pre-defined python script to make it easier for beginners
* GISAXS community might be interested in joining the discussion on resolution functions
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 

* To be contributed via “requests”/”patches” to the documentation sources.
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Feedback-loops available (from Artur) between McStas and BornAgain, but no fitting possible
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Making use of canSAS and ORSO standards
* Need to extend both the canSAS/ORSO formats towards GISAS
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 

* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

====“How-to”====
* Keep BA-group as core developers group. Contributions by the community on most urgent items
* have a section on BornAgain source/repository (called contributions). People can put contributions there, not mixing with main core. This does not interfere with complicated C++ core of BornAgain, but would benefit from Python scripts.
* Distribution of notes / goals / etc. + Conversation via cansas
** Need to re-populate and extend the cansas wiki for GISANS
* Occasional in-person workshops, first one at ILL first half of 2026 (aim at max ca. 40 people. Aim that each facility cover the travel costs of the participating individuals?)
** Goal: Extending the roadmap + defining a priority list
** If possible, connection to another event would be appreciated – otherwise we organize it independently
** Partial financing of meeting by SAGA team possible for ca. 10 people
** Making online attendance possible
** If possible, including an overview of current status from BornAgain to all participants
* Further Notes from the ILL-Workshop on: [[/Notes How to go forward]]

=== First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 ===

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
[[File:HF_MuSc GISANS.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:Background ideas.pdf|thumb]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
* Instrument factors influence measurement strategies and tools are needed to aid this process.

* Background - effects of inelastic scattering can change background.

* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.

* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.

* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry

* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed

==== Outlook ====
* Letter in "Neutron News"

/Background handling

2026-03-25T15:27:08Z

Annikastellhorn:

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-03-25T15:26:16Z

Annikastellhorn: /* Discussion session notes */

=== Overview ===
'''GISANS Data Reduction and Analysis Upgrades Initiative:''' 
An initiative on “GISANS data reduction and analysis upgrades” was launched at the GISAXS-25 meeting in Hamburg in November 2025. The objective of the initiative is to develop a generic, instrument-independent software framework for GISANS data reduction and analysis that can be used across neutron research facilities.

'''Approach:''' 
The proposal is to build upon the open-source software package BornAgain and to identify and define the key developments required for broader GISANS usability. Planned areas of improvement include:
* more flexible treatment of instrument resolution,
* improved background subtraction,
* clearer approaches to normalization,
* increased interoperability with existing analysis and reduction software tools.

'''Planned Work:''' 
A dedicated working group has to be established with two primary tasks:
1. Defining a roadmap and priority list for the required functionality.
2. Implementing these features in collaboration with the BornAgain core development team. Contributions may include code development, example scripts, and other shared resources.

'''Next Steps:''' 
The GISANS community is being invited to participate in the initiative. A first workshop is planned for the first half of 2026, with Institut Laue-Langevin (ILL) proposed as the host venue. The meeting is intended to be held on-site, with the option for remote attendance.

=== Online Meeting 2025-11-13 ===

'''Participants:''' 
Adrian Rennie (Uppsala Univ.), Apostolos Vagias, Annika Stellhorn (ESS), Dirk Honecker (STFC-ISIS), Artur Glavic (PSI), Sebastian Jaksch (ESS). 
BornAgain team: Joachim Wuttke, Mikhail Svechnikov, Ammar Nejati. 
SAGA Team: Tom Arnold, Tommy Nylander, Max Wolff, Milan Klausz. 

'''Date:''' 
13th November 2025

'''Content:''' 
1. Introduction (Annika) 
2. Current activites in BornAgain (BA) (Joachim Wuttke) 
3. “Quick” Roadmap discussion 
4. Preparation of on-site meeting at ILL 
5. “How-to” 

====Introduction (Annika)====
* Goal: Getting an instrument-independent GISANS software
* Question: (For using BornAgain as such) How to make it attractive for more users? How to implement together more features?
* Answers: Most important to (i) define most necessary items, (ii) keep it simple, (iii) have a core developers team (the current BA-team), that (iv) gets help by python/C++-code contributions by the community – e.g. into a separate repository that will be reviewed by the core team
* Next steps: 2-3 days in-person meeting. Current idea: at ILL. Contributors: from each neutron source (experimentalists + data scientists) + the GISAS core users.

====Current activities in BornAgain (BA) (Joachim Wuttke)====
* BA is an open-source software, everyone can access and contribute
* Idea: Make it simpler, cleaner, more accessible, in the best case community-maintained to get a long-term manageable project
* Nearly everything is possible from Python interface, but not from the GUI.
* The GUI shall not be altered too much for the next coming years
* Plans: First achieving simplification, afterwards working on extensions
* Current biggest challenge: handling of coherent vs. incoherent scattering contributions
* Next goals: Auto-generation of new geometric shapes

====Preparation of On-site meeting at ILL====
* Aim at first half of 2026
* Ask for (i) core-team dates, (ii) community dates

====“Quick” Roadmap discussion====

'''POINT A.+B. ToF-GISANS + Multiple scattering''' 
* Possible in Python / via jupyter notebook in BA. Keep it there.
* Computationally heavy: has to be inserted into BA via slicing it down to monochromatic slices with individual resolution functions
* Needs to be done via ROI-definition
* Complicated for users:
** especially due to complicated connection to multiple scattering & incoherent scattering
** different backgrounds for different lambda/incident angles which is additionally dominated by multiple scattering
* Need to differentiate between: (i) incoherent multiple scattering, (ii) multiple scattering for which Born approximation breaks down
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* A challenge for weakly scattering systems
* Connected to points (A) + (B).
* Challenging case of angular-dependent “incoherent multiple scattering” in many soft matter systems
* The generic question “how do we subtract bkg?” becomes relevant as well
* Again, computationally heavy/long. Possible solution: ROI-definition
* Existing user scripts that have proven to work, can be implemented into BA
* Influence from hydrogen?
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* In SAS, we put units of cm-1 (or sr-1).
* In reflectivity, data are normally reported as ratio to incident beam (flux or counts).
* In GISAS, not clear consensus as to how data are reported
* Correct background substraction and its impact on normalization and absolute intensity calculation has to be taken care of
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* For data analysis:
** Have the possibility to import missing form factors from e.g. SASView, SASfit?
** need a plug-in feature that is compatible with existing other software, e.g. via FabIO (Can it now read all detector formats into BornAgain?)
** Advancements of fitting procedures to 2d scattering patterns?
**. "Easy and quick" data analysis features like creating 1d cuts etc.?
* For data reduction:
** Needs to be compatible to existing software like GRASP or MANTID
** Key: well-defined .nxs (canSAS) standard
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Instrument-dependent aspects (more than 1 detector arrays with potentially useful and unexploited information, sample geometry, detector-background, polarization efficiency, error-bars) have to be reduced at the instrument as usual
* Calculation of resolution function in proper coordinate system --> can be tricky for non-experts.
* Important for implementation in BornAgain: Q/lambda resolution functions
** Can be implemented fast (via “Issue Tracker” of BornAgain?)
** Best to start from working/existing models
* Polarization-dependent 4-channel calculation could be a pre-defined python script to make it easier for beginners
* GISAXS community might be interested in joining the discussion on resolution functions
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 

* To be contributed via “requests”/”patches” to the documentation sources.
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Feedback-loops available (from Artur) between McStas and BornAgain, but no fitting possible
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Making use of canSAS and ORSO standards
* Need to extend both the canSAS/ORSO formats towards GISAS
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 

* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

====“How-to”====
* Keep BA-group as core developers group. Contributions by the community on most urgent items
* have a section on BornAgain source/repository (called contributions). People can put contributions there, not mixing with main core. This does not interfere with complicated C++ core of BornAgain, but would benefit from Python scripts.
* Distribution of notes / goals / etc. + Conversation via cansas
** Need to re-populate and extend the cansas wiki for GISANS
* Occasional in-person workshops, first one at ILL first half of 2026 (aim at max ca. 40 people. Aim that each facility cover the travel costs of the participating individuals?)
** Goal: Extending the roadmap + defining a priority list
** If possible, connection to another event would be appreciated – otherwise we organize it independently
** Partial financing of meeting by SAGA team possible for ca. 10 people
** Making online attendance possible
** If possible, including an overview of current status from BornAgain to all participants
* Further Notes from the ILL-Workshop on: [[/Notes How to go forward]]

=== First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 ===

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
[[File:GISANS 2026 File Formats - Brian Maranville.pdf|thumb|Introduction on File Formats - Brian Maranville]]
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
* Instrument factors influence measurement strategies and tools are needed to aid this process.

* Background - effects of inelastic scattering can change background.

* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.

* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.

* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry

* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed

==== Outlook ====
* Letter in "Neutron News"

File:GISANS 2026 File Formats - Brian Maranville.pdf

2026-03-25T15:25:48Z

Annikastellhorn:

Introduction on File Formats - Brian Maranville

File:HF MuSc GISANS.pdf

2026-03-25T15:21:29Z

Annikastellhorn:

Introduction on Multiple Scattering - Henrich Frielinghaus

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-03-25T14:01:41Z

Annikastellhorn:

=== Overview ===
'''GISANS Data Reduction and Analysis Upgrades Initiative:''' 
An initiative on “GISANS data reduction and analysis upgrades” was launched at the GISAXS-25 meeting in Hamburg in November 2025. The objective of the initiative is to develop a generic, instrument-independent software framework for GISANS data reduction and analysis that can be used across neutron research facilities.

'''Approach:''' 
The proposal is to build upon the open-source software package BornAgain and to identify and define the key developments required for broader GISANS usability. Planned areas of improvement include:
* more flexible treatment of instrument resolution,
* improved background subtraction,
* clearer approaches to normalization,
* increased interoperability with existing analysis and reduction software tools.

'''Planned Work:''' 
A dedicated working group has to be established with two primary tasks:
1. Defining a roadmap and priority list for the required functionality.
2. Implementing these features in collaboration with the BornAgain core development team. Contributions may include code development, example scripts, and other shared resources.

'''Next Steps:''' 
The GISANS community is being invited to participate in the initiative. A first workshop is planned for the first half of 2026, with Institut Laue-Langevin (ILL) proposed as the host venue. The meeting is intended to be held on-site, with the option for remote attendance.

=== Online Meeting 2025-11-13 ===

'''Participants:''' 
Adrian Rennie (Uppsala Univ.), Apostolos Vagias, Annika Stellhorn (ESS), Dirk Honecker (STFC-ISIS), Artur Glavic (PSI), Sebastian Jaksch (ESS). 
BornAgain team: Joachim Wuttke, Mikhail Svechnikov, Ammar Nejati. 
SAGA Team: Tom Arnold, Tommy Nylander, Max Wolff, Milan Klausz. 

'''Date:''' 
13th November 2025

'''Content:''' 
1. Introduction (Annika) 
2. Current activites in BornAgain (BA) (Joachim Wuttke) 
3. “Quick” Roadmap discussion 
4. Preparation of on-site meeting at ILL 
5. “How-to” 

====Introduction (Annika)====
* Goal: Getting an instrument-independent GISANS software
* Question: (For using BornAgain as such) How to make it attractive for more users? How to implement together more features?
* Answers: Most important to (i) define most necessary items, (ii) keep it simple, (iii) have a core developers team (the current BA-team), that (iv) gets help by python/C++-code contributions by the community – e.g. into a separate repository that will be reviewed by the core team
* Next steps: 2-3 days in-person meeting. Current idea: at ILL. Contributors: from each neutron source (experimentalists + data scientists) + the GISAS core users.

====Current activities in BornAgain (BA) (Joachim Wuttke)====
* BA is an open-source software, everyone can access and contribute
* Idea: Make it simpler, cleaner, more accessible, in the best case community-maintained to get a long-term manageable project
* Nearly everything is possible from Python interface, but not from the GUI.
* The GUI shall not be altered too much for the next coming years
* Plans: First achieving simplification, afterwards working on extensions
* Current biggest challenge: handling of coherent vs. incoherent scattering contributions
* Next goals: Auto-generation of new geometric shapes

====Preparation of On-site meeting at ILL====
* Aim at first half of 2026
* Ask for (i) core-team dates, (ii) community dates

====“Quick” Roadmap discussion====

'''POINT A.+B. ToF-GISANS + Multiple scattering''' 
* Possible in Python / via jupyter notebook in BA. Keep it there.
* Computationally heavy: has to be inserted into BA via slicing it down to monochromatic slices with individual resolution functions
* Needs to be done via ROI-definition
* Complicated for users:
** especially due to complicated connection to multiple scattering & incoherent scattering
** different backgrounds for different lambda/incident angles which is additionally dominated by multiple scattering
* Need to differentiate between: (i) incoherent multiple scattering, (ii) multiple scattering for which Born approximation breaks down
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* A challenge for weakly scattering systems
* Connected to points (A) + (B).
* Challenging case of angular-dependent “incoherent multiple scattering” in many soft matter systems
* The generic question “how do we subtract bkg?” becomes relevant as well
* Again, computationally heavy/long. Possible solution: ROI-definition
* Existing user scripts that have proven to work, can be implemented into BA
* Influence from hydrogen?
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* In SAS, we put units of cm-1 (or sr-1).
* In reflectivity, data are normally reported as ratio to incident beam (flux or counts).
* In GISAS, not clear consensus as to how data are reported
* Correct background substraction and its impact on normalization and absolute intensity calculation has to be taken care of
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* For data analysis:
** Have the possibility to import missing form factors from e.g. SASView, SASfit?
** need a plug-in feature that is compatible with existing other software, e.g. via FabIO (Can it now read all detector formats into BornAgain?)
** Advancements of fitting procedures to 2d scattering patterns?
**. "Easy and quick" data analysis features like creating 1d cuts etc.?
* For data reduction:
** Needs to be compatible to existing software like GRASP or MANTID
** Key: well-defined .nxs (canSAS) standard
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Instrument-dependent aspects (more than 1 detector arrays with potentially useful and unexploited information, sample geometry, detector-background, polarization efficiency, error-bars) have to be reduced at the instrument as usual
* Calculation of resolution function in proper coordinate system --> can be tricky for non-experts.
* Important for implementation in BornAgain: Q/lambda resolution functions
** Can be implemented fast (via “Issue Tracker” of BornAgain?)
** Best to start from working/existing models
* Polarization-dependent 4-channel calculation could be a pre-defined python script to make it easier for beginners
* GISAXS community might be interested in joining the discussion on resolution functions
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 

* To be contributed via “requests”/”patches” to the documentation sources.
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Feedback-loops available (from Artur) between McStas and BornAgain, but no fitting possible
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Making use of canSAS and ORSO standards
* Need to extend both the canSAS/ORSO formats towards GISAS
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 

* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

====“How-to”====
* Keep BA-group as core developers group. Contributions by the community on most urgent items
* have a section on BornAgain source/repository (called contributions). People can put contributions there, not mixing with main core. This does not interfere with complicated C++ core of BornAgain, but would benefit from Python scripts.
* Distribution of notes / goals / etc. + Conversation via cansas
** Need to re-populate and extend the cansas wiki for GISANS
* Occasional in-person workshops, first one at ILL first half of 2026 (aim at max ca. 40 people. Aim that each facility cover the travel costs of the participating individuals?)
** Goal: Extending the roadmap + defining a priority list
** If possible, connection to another event would be appreciated – otherwise we organize it independently
** Partial financing of meeting by SAGA team possible for ca. 10 people
** Making online attendance possible
** If possible, including an overview of current status from BornAgain to all participants
* Further Notes from the ILL-Workshop on: [[/Notes How to go forward]]

=== First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 ===

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====
* Instrument factors influence measurement strategies and tools are needed to aid this process.

* Background - effects of inelastic scattering can change background.

* Resolution is important both as regards wavelength and angle. The latter depends on collimation as well as footprint on the sample and spatial resolution of the detector. Full interpretation of data is likely to require extensive information to be available with processed data.

* Data reduction from raw data will require establishment of appropriate data formats for input to existing modelling and analysis software. The software may also need development to fully exploit the information that is available.

* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry

* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed

==== Outlook ====
* Letter in "Neutron News"

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-03-25T13:53:14Z

Annikastellhorn:

=== Overview ===
'''GISANS Data Reduction and Analysis Upgrades Initiative:''' 
An initiative on “GISANS data reduction and analysis upgrades” was launched at the GISAXS-25 meeting in Hamburg in November 2025. The objective of the initiative is to develop a generic, instrument-independent software framework for GISANS data reduction and analysis that can be used across neutron research facilities.

'''Approach:''' 
The proposal is to build upon the open-source software package BornAgain and to identify and define the key developments required for broader GISANS usability. Planned areas of improvement include:
* more flexible treatment of instrument resolution,
* improved background subtraction,
* clearer approaches to normalization,
* increased interoperability with existing analysis and reduction software tools.

'''Planned Work:''' 
A dedicated working group has to be established with two primary tasks:
1. Defining a roadmap and priority list for the required functionality.
2. Implementing these features in collaboration with the BornAgain core development team. Contributions may include code development, example scripts, and other shared resources.

'''Next Steps:''' 
The GISANS community is being invited to participate in the initiative. A first workshop is planned for the first half of 2026, with Institut Laue-Langevin (ILL) proposed as the host venue. The meeting is intended to be held on-site, with the option for remote attendance.

=== Online Meeting 2025-11-13 ===

'''Participants:''' 
Adrian Rennie (Uppsala Univ.), Apostolos Vagias, Annika Stellhorn (ESS), Dirk Honecker (STFC-ISIS), Artur Glavic (PSI), Sebastian Jaksch (ESS). 
BornAgain team: Joachim Wuttke, Mikhail Svechnikov, Ammar Nejati. 
SAGA Team: Tom Arnold, Tommy Nylander, Max Wolff, Milan Klausz. 

'''Date:''' 
13th November 2025

'''Content:''' 
1. Introduction (Annika) 
2. Current activites in BornAgain (BA) (Joachim Wuttke) 
3. “Quick” Roadmap discussion 
4. Preparation of on-site meeting at ILL 
5. “How-to” 

====Introduction (Annika)====
* Goal: Getting an instrument-independent GISANS software
* Question: (For using BornAgain as such) How to make it attractive for more users? How to implement together more features?
* Answers: Most important to (i) define most necessary items, (ii) keep it simple, (iii) have a core developers team (the current BA-team), that (iv) gets help by python/C++-code contributions by the community – e.g. into a separate repository that will be reviewed by the core team
* Next steps: 2-3 days in-person meeting. Current idea: at ILL. Contributors: from each neutron source (experimentalists + data scientists) + the GISAS core users.

====Current activities in BornAgain (BA) (Joachim Wuttke)====
* BA is an open-source software, everyone can access and contribute
* Idea: Make it simpler, cleaner, more accessible, in the best case community-maintained to get a long-term manageable project
* Nearly everything is possible from Python interface, but not from the GUI.
* The GUI shall not be altered too much for the next coming years
* Plans: First achieving simplification, afterwards working on extensions
* Current biggest challenge: handling of coherent vs. incoherent scattering contributions
* Next goals: Auto-generation of new geometric shapes

====Preparation of On-site meeting at ILL====
* Aim at first half of 2026
* Ask for (i) core-team dates, (ii) community dates

====“Quick” Roadmap discussion====

'''POINT A.+B. ToF-GISANS + Multiple scattering''' 
* Possible in Python / via jupyter notebook in BA. Keep it there.
* Computationally heavy: has to be inserted into BA via slicing it down to monochromatic slices with individual resolution functions
* Needs to be done via ROI-definition
* Complicated for users:
** especially due to complicated connection to multiple scattering & incoherent scattering
** different backgrounds for different lambda/incident angles which is additionally dominated by multiple scattering
* Need to differentiate between: (i) incoherent multiple scattering, (ii) multiple scattering for which Born approximation breaks down
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* A challenge for weakly scattering systems
* Connected to points (A) + (B).
* Challenging case of angular-dependent “incoherent multiple scattering” in many soft matter systems
* The generic question “how do we subtract bkg?” becomes relevant as well
* Again, computationally heavy/long. Possible solution: ROI-definition
* Existing user scripts that have proven to work, can be implemented into BA
* Influence from hydrogen?
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* In SAS, we put units of cm-1 (or sr-1).
* In reflectivity, data are normally reported as ratio to incident beam (flux or counts).
* In GISAS, not clear consensus as to how data are reported
* Correct background substraction and its impact on normalization and absolute intensity calculation has to be taken care of
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* For data analysis:
** Have the possibility to import missing form factors from e.g. SASView, SASfit?
** need a plug-in feature that is compatible with existing other software, e.g. via FabIO (Can it now read all detector formats into BornAgain?)
** Advancements of fitting procedures to 2d scattering patterns?
**. "Easy and quick" data analysis features like creating 1d cuts etc.?
* For data reduction:
** Needs to be compatible to existing software like GRASP or MANTID
** Key: well-defined .nxs (canSAS) standard
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Instrument-dependent aspects (more than 1 detector arrays with potentially useful and unexploited information, sample geometry, detector-background, polarization efficiency, error-bars) have to be reduced at the instrument as usual
* Calculation of resolution function in proper coordinate system --> can be tricky for non-experts.
* Important for implementation in BornAgain: Q/lambda resolution functions
** Can be implemented fast (via “Issue Tracker” of BornAgain?)
** Best to start from working/existing models
* Polarization-dependent 4-channel calculation could be a pre-defined python script to make it easier for beginners
* GISAXS community might be interested in joining the discussion on resolution functions
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 

* To be contributed via “requests”/”patches” to the documentation sources.
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Feedback-loops available (from Artur) between McStas and BornAgain, but no fitting possible
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Making use of canSAS and ORSO standards
* Need to extend both the canSAS/ORSO formats towards GISAS
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 

* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

====“How-to”====
* Keep BA-group as core developers group. Contributions by the community on most urgent items
* have a section on BornAgain source/repository (called contributions). People can put contributions there, not mixing with main core. This does not interfere with complicated C++ core of BornAgain, but would benefit from Python scripts.
* Distribution of notes / goals / etc. + Conversation via cansas
** Need to re-populate and extend the cansas wiki for GISANS
* Occasional in-person workshops, first one at ILL first half of 2026 (aim at max ca. 40 people. Aim that each facility cover the travel costs of the participating individuals?)
** Goal: Extending the roadmap + defining a priority list
** If possible, connection to another event would be appreciated – otherwise we organize it independently
** Partial financing of meeting by SAGA team possible for ca. 10 people
** Making online attendance possible
** If possible, including an overview of current status from BornAgain to all participants
* Further Notes from the ILL-Workshop on: [[/Notes How to go forward]]

=== First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 ===

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====

==== Outlook ====
* Letter in "Neutron News"

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-03-25T13:51:51Z

Annikastellhorn:

=== Overview ===
'''GISANS Data Reduction and Analysis Upgrades Initiative:''' 
An initiative on “GISANS data reduction and analysis upgrades” was launched at the GISAXS-25 meeting in Hamburg in November 2025. The objective of the initiative is to develop a generic, instrument-independent software framework for GISANS data reduction and analysis that can be used across neutron research facilities.

'''Approach:''' 
The proposal is to build upon the open-source software package BornAgain and to identify and define the key developments required for broader GISANS usability. Planned areas of improvement include:
* more flexible treatment of instrument resolution,
* improved background subtraction,
* clearer approaches to normalization,
* increased interoperability with existing analysis and reduction software tools.

'''Planned Work:''' 
A dedicated working group has to be established with two primary tasks:
1. Defining a roadmap and priority list for the required functionality.
2. Implementing these features in collaboration with the BornAgain core development team. Contributions may include code development, example scripts, and other shared resources.

'''Next Steps:''' 
The GISANS community is being invited to participate in the initiative. A first workshop is planned for the first half of 2026, with Institut Laue-Langevin (ILL) proposed as the host venue. The meeting is intended to be held on-site, with the option for remote attendance.

=== Online Meeting 2025-11-13 ===

'''Participants:''' 
Adrian Rennie (Uppsala Univ.), Apostolos Vagias, Annika Stellhorn (ESS), Dirk Honecker (STFC-ISIS), Artur Glavic (PSI), Sebastian Jaksch (ESS). 
BornAgain team: Joachim Wuttke, Mikhail Svechnikov, Ammar Nejati. 
SAGA Team: Tom Arnold, Tommy Nylander, Max Wolff, Milan Klausz. 

'''Date:''' 
13th November 2025

'''Content:''' 
1. Introduction (Annika) 
2. Current activites in BornAgain (BA) (Joachim Wuttke) 
3. “Quick” Roadmap discussion 
4. Preparation of on-site meeting at ILL 
5. “How-to” 

====Introduction (Annika)====
* Goal: Getting an instrument-independent GISANS software
* Question: (For using BornAgain as such) How to make it attractive for more users? How to implement together more features?
* Answers: Most important to (i) define most necessary items, (ii) keep it simple, (iii) have a core developers team (the current BA-team), that (iv) gets help by python/C++-code contributions by the community – e.g. into a separate repository that will be reviewed by the core team
* Next steps: 2-3 days in-person meeting. Current idea: at ILL. Contributors: from each neutron source (experimentalists + data scientists) + the GISAS core users.

====Current activities in BornAgain (BA) (Joachim Wuttke)====
* BA is an open-source software, everyone can access and contribute
* Idea: Make it simpler, cleaner, more accessible, in the best case community-maintained to get a long-term manageable project
* Nearly everything is possible from Python interface, but not from the GUI.
* The GUI shall not be altered too much for the next coming years
* Plans: First achieving simplification, afterwards working on extensions
* Current biggest challenge: handling of coherent vs. incoherent scattering contributions
* Next goals: Auto-generation of new geometric shapes

====Preparation of On-site meeting at ILL====
* Aim at first half of 2026
* Ask for (i) core-team dates, (ii) community dates

====“Quick” Roadmap discussion====

'''POINT A.+B. ToF-GISANS + Multiple scattering''' 
* Possible in Python / via jupyter notebook in BA. Keep it there.
* Computationally heavy: has to be inserted into BA via slicing it down to monochromatic slices with individual resolution functions
* Needs to be done via ROI-definition
* Complicated for users:
** especially due to complicated connection to multiple scattering & incoherent scattering
** different backgrounds for different lambda/incident angles which is additionally dominated by multiple scattering
* Need to differentiate between: (i) incoherent multiple scattering, (ii) multiple scattering for which Born approximation breaks down
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* A challenge for weakly scattering systems
* Connected to points (A) + (B).
* Challenging case of angular-dependent “incoherent multiple scattering” in many soft matter systems
* The generic question “how do we subtract bkg?” becomes relevant as well
* Again, computationally heavy/long. Possible solution: ROI-definition
* Existing user scripts that have proven to work, can be implemented into BA
* Influence from hydrogen?
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* In SAS, we put units of cm-1 (or sr-1).
* In reflectivity, data are normally reported as ratio to incident beam (flux or counts).
* In GISAS, not clear consensus as to how data are reported
* Correct background substraction and its impact on normalization and absolute intensity calculation has to be taken care of
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* For data analysis:
** Have the possibility to import missing form factors from e.g. SASView, SASfit?
** need a plug-in feature that is compatible with existing other software, e.g. via FabIO (Can it now read all detector formats into BornAgain?)
** Advancements of fitting procedures to 2d scattering patterns?
**. "Easy and quick" data analysis features like creating 1d cuts etc.?
* For data reduction:
** Needs to be compatible to existing software like GRASP or MANTID
** Key: well-defined .nxs (canSAS) standard
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Instrument-dependent aspects (more than 1 detector arrays with potentially useful and unexploited information, sample geometry, detector-background, polarization efficiency, error-bars) have to be reduced at the instrument as usual
* Calculation of resolution function in proper coordinate system --> can be tricky for non-experts.
* Important for implementation in BornAgain: Q/lambda resolution functions
** Can be implemented fast (via “Issue Tracker” of BornAgain?)
** Best to start from working/existing models
* Polarization-dependent 4-channel calculation could be a pre-defined python script to make it easier for beginners
* GISAXS community might be interested in joining the discussion on resolution functions
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 

* To be contributed via “requests”/”patches” to the documentation sources.
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Feedback-loops available (from Artur) between McStas and BornAgain, but no fitting possible
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Making use of canSAS and ORSO standards
* Need to extend both the canSAS/ORSO formats towards GISAS
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 

* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

====“How-to”====
* Keep BA-group as core developers group. Contributions by the community on most urgent items
* have a section on BornAgain source/repository (called contributions). People can put contributions there, not mixing with main core. This does not interfere with complicated C++ core of BornAgain, but would benefit from Python scripts.
* Distribution of notes / goals / etc. + Conversation via cansas
** Need to re-populate and extend the cansas wiki for GISANS
* Occasional in-person workshops, first one at ILL first half of 2026 (aim at max ca. 40 people. Aim that each facility cover the travel costs of the participating individuals?)
** Goal: Extending the roadmap + defining a priority list
** If possible, connection to another event would be appreciated – otherwise we organize it independently
** Partial financing of meeting by SAGA team possible for ca. 10 people
** Making online attendance possible
** If possible, including an overview of current status from BornAgain to all participants
* Further Notes from the ILL-Workshop on: [[/Notes How to go forward]]

=== First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 ===

[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-03-25T13:51:06Z

Annikastellhorn:

=== Overview ===
'''GISANS Data Reduction and Analysis Upgrades Initiative:''' 
An initiative on “GISANS data reduction and analysis upgrades” was launched at the GISAXS-25 meeting in Hamburg in November 2025. The objective of the initiative is to develop a generic, instrument-independent software framework for GISANS data reduction and analysis that can be used across neutron research facilities.

'''Approach:''' 
The proposal is to build upon the open-source software package BornAgain and to identify and define the key developments required for broader GISANS usability. Planned areas of improvement include:
* more flexible treatment of instrument resolution,
* improved background subtraction,
* clearer approaches to normalization,
* increased interoperability with existing analysis and reduction software tools.

'''Planned Work:''' 
A dedicated working group has to be established with two primary tasks:
1. Defining a roadmap and priority list for the required functionality.
2. Implementing these features in collaboration with the BornAgain core development team. Contributions may include code development, example scripts, and other shared resources.

'''Next Steps:''' 
The GISANS community is being invited to participate in the initiative. A first workshop is planned for the first half of 2026, with Institut Laue-Langevin (ILL) proposed as the host venue. The meeting is intended to be held on-site, with the option for remote attendance.

=== Online Meeting 2025-11-13 ===

'''Participants:''' 
Adrian Rennie (Uppsala Univ.), Apostolos Vagias, Annika Stellhorn (ESS), Dirk Honecker (STFC-ISIS), Artur Glavic (PSI), Sebastian Jaksch (ESS). 
BornAgain team: Joachim Wuttke, Mikhail Svechnikov, Ammar Nejati. 
SAGA Team: Tom Arnold, Tommy Nylander, Max Wolff, Milan Klausz. 

'''Date:''' 
13th November 2025

'''Content:''' 
1. Introduction (Annika) 
2. Current activites in BornAgain (BA) (Joachim Wuttke) 
3. “Quick” Roadmap discussion 
4. Preparation of on-site meeting at ILL 
5. “How-to” 

====Introduction (Annika)====
* Goal: Getting an instrument-independent GISANS software
* Question: (For using BornAgain as such) How to make it attractive for more users? How to implement together more features?
* Answers: Most important to (i) define most necessary items, (ii) keep it simple, (iii) have a core developers team (the current BA-team), that (iv) gets help by python/C++-code contributions by the community – e.g. into a separate repository that will be reviewed by the core team
* Next steps: 2-3 days in-person meeting. Current idea: at ILL. Contributors: from each neutron source (experimentalists + data scientists) + the GISAS core users.

====Current activities in BornAgain (BA) (Joachim Wuttke)====
* BA is an open-source software, everyone can access and contribute
* Idea: Make it simpler, cleaner, more accessible, in the best case community-maintained to get a long-term manageable project
* Nearly everything is possible from Python interface, but not from the GUI.
* The GUI shall not be altered too much for the next coming years
* Plans: First achieving simplification, afterwards working on extensions
* Current biggest challenge: handling of coherent vs. incoherent scattering contributions
* Next goals: Auto-generation of new geometric shapes

====Preparation of On-site meeting at ILL====
* Aim at first half of 2026
* Ask for (i) core-team dates, (ii) community dates

====“Quick” Roadmap discussion====

'''POINT A.+B. ToF-GISANS + Multiple scattering''' 
* Possible in Python / via jupyter notebook in BA. Keep it there.
* Computationally heavy: has to be inserted into BA via slicing it down to monochromatic slices with individual resolution functions
* Needs to be done via ROI-definition
* Complicated for users:
** especially due to complicated connection to multiple scattering & incoherent scattering
** different backgrounds for different lambda/incident angles which is additionally dominated by multiple scattering
* Need to differentiate between: (i) incoherent multiple scattering, (ii) multiple scattering for which Born approximation breaks down
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* A challenge for weakly scattering systems
* Connected to points (A) + (B).
* Challenging case of angular-dependent “incoherent multiple scattering” in many soft matter systems
* The generic question “how do we subtract bkg?” becomes relevant as well
* Again, computationally heavy/long. Possible solution: ROI-definition
* Existing user scripts that have proven to work, can be implemented into BA
* Influence from hydrogen?
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* In SAS, we put units of cm-1 (or sr-1).
* In reflectivity, data are normally reported as ratio to incident beam (flux or counts).
* In GISAS, not clear consensus as to how data are reported
* Correct background substraction and its impact on normalization and absolute intensity calculation has to be taken care of
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* For data analysis:
** Have the possibility to import missing form factors from e.g. SASView, SASfit?
** need a plug-in feature that is compatible with existing other software, e.g. via FabIO (Can it now read all detector formats into BornAgain?)
** Advancements of fitting procedures to 2d scattering patterns?
**. "Easy and quick" data analysis features like creating 1d cuts etc.?
* For data reduction:
** Needs to be compatible to existing software like GRASP or MANTID
** Key: well-defined .nxs (canSAS) standard
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Instrument-dependent aspects (more than 1 detector arrays with potentially useful and unexploited information, sample geometry, detector-background, polarization efficiency, error-bars) have to be reduced at the instrument as usual
* Calculation of resolution function in proper coordinate system --> can be tricky for non-experts.
* Important for implementation in BornAgain: Q/lambda resolution functions
** Can be implemented fast (via “Issue Tracker” of BornAgain?)
** Best to start from working/existing models
* Polarization-dependent 4-channel calculation could be a pre-defined python script to make it easier for beginners
* GISAXS community might be interested in joining the discussion on resolution functions
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 

* To be contributed via “requests”/”patches” to the documentation sources.
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Feedback-loops available (from Artur) between McStas and BornAgain, but no fitting possible
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Making use of canSAS and ORSO standards
* Need to extend both the canSAS/ORSO formats towards GISAS
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 

* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 

* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

====“How-to”====
* Keep BA-group as core developers group. Contributions by the community on most urgent items
* have a section on BornAgain source/repository (called contributions). People can put contributions there, not mixing with main core. This does not interfere with complicated C++ core of BornAgain, but would benefit from Python scripts.
* Distribution of notes / goals / etc. + Conversation via cansas
** Need to re-populate and extend the cansas wiki for GISANS
* Occasional in-person workshops, first one at ILL first half of 2026 (aim at max ca. 40 people. Aim that each facility cover the travel costs of the participating individuals?)
** Goal: Extending the roadmap + defining a priority list
** If possible, connection to another event would be appreciated – otherwise we organize it independently
** Partial financing of meeting by SAGA team possible for ca. 10 people
** Making online attendance possible
** If possible, including an overview of current status from BornAgain to all participants
* Further Notes from the ILL-Workshop on: [[/Notes How to go forward]]

=== First workshop at ILL, France: "GISANS - Advancing data reduction and analysis" 2026-03-17/18 ===

==== Workshop programme ====
[[File:GISANS Programme FINAL.jpg|thumb|Workshop programme]]
==== Discussion session notes ====

'''POINT A. ToF-GISANS''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/ToF-GISANS]]

'''POINT B. Multiple scattering''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Multiple Scattering]]

'''POINT C. Background handling''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Background handling]]

'''POINT D. Normalization''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Normalization]]

'''POINT E. Using SANS software''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Using SANS software]]

'''POINT F / Instrumentation & Q/lambda resolution (different detector arrays, or, sample geometries-how is data reduced)''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Instrumentation & Q/lambda resolution]]

'''POINT G. Need good documentation''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Documentation]]

'''POINT H. Integration of McStas with BornAgain''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/McStas]]

'''POINT I. Get a common data format for GISANS data reduction:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Common Data Format]]

'''POINT J. Computer simulations / AI support:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Computer simulations / AI support]]

'''POINT K. Off-specular scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Off-Specular Scattering]]

'''POINT L. Magnetic Scattering:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Magnetic Scattering]]

'''POINT M. Data Reduction:''' 
* Presentation slides:
* Further Notes from the ILL-Workshop on: [[/Notes Data Reduction]]

==== Organizational notes ====

==== Summary ====

File:GISANS Programme FINAL.jpg

2026-03-25T13:50:44Z

Annikastellhorn:

Workshop programme

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-03-25T13:46:17Z

Annikastellhorn:

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-03-25T13:43:42Z

Annikastellhorn:

/Multiple Scattering

2026-03-19T07:49:55Z

Annikastellhorn:

Short summary of discussions/breakouts:

* Reflection and refraction should be excluded from multiple scattering
* Need to agree on a common nomenclature
* There are certain constraints for multiple scattering: mean free path length & coherence length, sample size / curvature / geometry
** They have to be identified before each experiment

Group 1

Philipp:Distorted Wave Born Approximation, is some sort of multiple scattering, because incoming beam is split into reflected and refracted beams?

Joachim: reflection from interface can be described as scattering, in Sinha paper, they discuss scattering from infinite volume and then describe reflection. Known way to deal with reflection and refraction, this gives DWBA. Scattering is not by interfaces, they are taken into account by DWBA.

Henrich: Parratt algorithm is a dynamic approach. it takes into account multiple reflections. Do not know how it can get more precise.

'''reflection and refraction should be excluded from multiple scattering'''

If we calculate all transmission and reflection coefficients, we are left with 16 reflection and transmission combination terms. Some have different momentum transfers. this is shown like reflection/refraction, reflection/reflection. should we call this multiple scattering?

Ammar: Multiple scattering: Born approximation is single scattering event. Multiple scattering comes with further scatterign events, is not included in DWBA. magnetic interactions. when they are important, we cannot reply on Born approximation, but use multiple scattering in solid state. when first scattering event happens, system responds. this process continues. is a dynamical process, not single kinematical process.

'''Need to decouple between "Dynamic" term bing different than dynamic (meaning energy transfer)'''

Boris: full solution, we have to consider changes in the sample. even i first order scattering calculations,

Philipp (question to Boris): have you ever confused the term dynamic scattering with inelastic scattering?
Boris: with ToF is feasible. 100 neV (depends on wavelengths), to see this you need reasonable resolution in pulse. perfect for SNS, here at ILL we have rather broad pulse.

experiment from Sascha Frank on standing/moving waves. if it is standing waves, density gives periodic structure and same stripes. alternatively, if we have one magnon / phonon, we have one branch (stokes/antistokes). the excitations produce the harmonic.

Philipp: we consider higher orders of BA as multiple scattering?
Boris: Born series valid for amplitudes and valid within the transverse coherence lengths, that all interfaces produce one plane wave in same direction if we have lateral homogeneity and interfere with each other. but, multiple scattering when events occur in sequence but are incoherent in between of them. it could be multiple specular reflection, but gap should be greater than transverse coherence length (where particles reflect multiply within 1 cm gap). It may look like a semantic difference. You take interference between events or not? multiple scattering requires than path length is much greater than mean free path (1/Sigma_total*density of the particles).

'''Joachim: multiple scattering (in book of Sears) is treated in terms of transport theory.'''
need to have a distance to avoid interference

Philipp: higher order BA should not be called multiple scattering. would it make sense to call it coherence?
Boris: case of neutron guide (each reflection is quantum mechanic, superrmiror, each collision is not correlated with eachother), case of waveguide (there is resonance layer in between, it is expected with microbeam waveguide where they try to get from edge of the sample and nothing comes in, because it violates the coherence). isndie, they are all coherent from top to substrate, in substrate it goes trhough the edge.
if sample is smaller than coherence length,

Philipp:H'''enrich, do you calculate with matrix formalism reflection and transmission in each layer and you use them to calculate incoherent multiple scattering in each particle? so, this mode that calculates z-amplitude is calculated?'''
Henrich: '''this is what I want to do.'''
Boris: if you shoot through the dge and look through the other edge, is feasible. if thre is resonance layer in between, 10 microns layer and look through the edge maybe

Boris: forming microbeams using resonance layers as waveguide is OK, only when you come from the edge. only there, you will get enhancement from the other edge. Mean free path for neutrons is cm or few mm. for 1cm , I hav one particle only.

Henrich: '''can I have several scattering events independently?'''
Boris: '''if the distance is much greater than mean free path (1/N*Sigma_total, roughly few mm)'''

Philipp: multiple
Boris: particle, part goes in forward direction and (multiple scattering does not play a role in reflectivity)

incoherent sum of reflectivities.

Henrich: if you come with alpha_i> alpha_c, in the deptth, you can have independent events. if alpha_i< alpha_c, multiple scattering does not play a role.

Joachim: what is typical thickness of samples in conventional SANS?
Henrich: 1mm to 5mm (5mm stronger intensity. mean free path length that decides. total scattering cross-section that determines

Boris: '''for cold neutrons, mean free path ~few mm. but, cohereence length projection 100microns, the sample should be larger than that. we have 2 constraints (one from coherence length and one from mean free path length, both compared to sample dimension).'''

if sample is too long, will not prevent multiple scattering happening. as long as the coherence effects are averaged out, we can have

Boris: coherence length 0.1mm, sample size 1 cm laterally. That what we usually use to fit reflectivity, we have many thousands of these coherence spots, we averaged modulus square of reflectivity. incoherent sum of all coherence length (this is why it is proportional to projected areas on the beam). with very slow neutrons, this is possible, but nothing penetrates. example is whispering gallery. when there is multiple reflection from different mirrors circled around, one can turn direction of neutron (1cm radius and coherence length is 1mm) --> in such situation, multiple off-specular scattering. but this is curved surface

/Normalization

2026-03-19T07:24:37Z

Annikastellhorn:

Short summary from discussions/breakouts:
* Full quantitative normalization procedure:
** measuring GISANS together with NR & Off-specular scattering, to view the whole Q-space.
* If this is not feasible:
** Same as topic "Background": each system has to be classified for its way "how to be treated" - Survey needed!
* General aspects (sample independent):
** Precise I(lambda) normalization of the beamlines has to be performed

Notes:
* for normalization it should be taken into account hand-in-hand: Specular reflectivity measured and simulated via Parrat and Off-specular/GISANS measured and simulated via DWBA!
** Can NR help as a "reference" to normalize the GISANS measurement correctly - should it always go together?
** This is not possible for some of the existing beamlines where GISANS can be performed but NR not, especially for Monochromatic sources!
** At Tof-GISANS beamlines one could aim at getting the "NR" by measuring GISANS at different incident angles
* Another problem: we loose information on the background and on the correct normalization factor by the fact that we do not measure the whole real space anyhow, as the detector has finite size
* there are two different problems:
** a fully quantitative measurement and
** a reference to "1", where it would depend on the sample and the physics to be measured how to normalize (e.g., superconducting systems: with ref. via the T>Tc state, magnetic systems: with reference via the saturated state) BUT: this reference to "another sample state" is not for all systems possible. What then?
* Regarding the question "can magnetic references help" - this can not generally be done, as changing the layer system would impact on the sld, the background, the normalization, etc.
* Does the "correct normalization" only get critical if the background level is that high that changing the background in the simulation would change the simulated sld? Is that the same in NR and GISANS?
* What can you get from Q=0 in a GISANS measurement? Can one at all extract a quantitave solution from a GISANS measurement? Should rather we aim at always having proper reference systems that the cross section can be compared with for getting the physical parameters needed?

******
******

Henrich

Normalization
'''For normalization, important to know the footprint through reflectivity measurements'''.

Footprint correction (in reflectivity mode) should be best done before we do normalization

Si samples with known material, known SLD--> would that help? To have comparable geometry to work at all?
100nm etched 100 A wide roofs in Si and backfilled with Fe, to calculate expected intensity and calculate SLD that you have in the sample.

We do nano-etching with electron beam welding on the surface. Stripes should be fine, but we need to define orientation measurement, so it would be easier.

JF: Truncated rods can be difficult , because by subtle variations of angle, the scattering pattern changes drastically.

SJ: need to find out what can be done with chemical etching and electron beam etching. Have 1cm - 2 cm in all dimensions. If you work with microsample (square mm), footprint is way larger than whatever you have.

Reference sample should have same dimensions as real sample.

JK: Even if you have the reference samples, how do they help get the correct intensity?

PG: you double-check your data reduction, you check your calibration (features at same q-values), are absolute intensities at the same value?, to know how reproducible are. It is more for reproducibility.

PG: '''Normalization to direct beam, for GISANS we want to underilluminate (otherwise, we get lots of background)'''

JF: You measure difference in the film with contrast. If you do not know your footprint, you will not know your incident angle and the wavelength to the extend you want.

PG: All measurements we did with GISANS (large sample and small sample slits) we ensured underillumination.

PG: FIGARO --> ToF-GISANS was not easy.

SJ: More and more certain that we probably need one additional measurement:
- One reference sample
- One additional measurement with low intensity where we confine the beam very small, where footpirnt calculation becomes easier that we can use later to calibrate the measurement where maybe we can overilluminate
(JF: not sure if this will work. In your measurement where you overilluminate, e.g. resolution not that good, you measure GISANS over different depths.You do very different experiments. Might be useful but not simple scaling.)

SJ: for the moment, only simplistic approach. Without additional reflectometry, very hard to go to quantitative measurements.

AK: '''The approach of using the monitor will work, with sample big enough not to have overillumination problems'''.
PG: if it works, having GISANS with absolute intensity will be very valuable. The size of nanoparticle will define GISANS intensity.

PG: '''discussion about off-specular and cases where it influences direct beam and specular beam.'''
AK: you have troubles understanding where you define specular beam on the detector.

SJ: Reflectometry, we normalize to intensity of incident beam. We do specular reflectivity curve. Everything in plane is correlated, and everything not landing on specular beam is not collected.

PG: in case that you have such strong off-specular scattering, that you influence specular intensity. Boris has published couple of papers that he proposes to deal with this problem.

JK: To get all this info, you need to simultaneously fit spec reflectivity with off-spec and GISANS and

Simultaneously: exact same beam and sample,

'''Footprint correction (geometric considerations for absolute intensity)'''

/Background handling

2026-03-19T07:19:19Z

Annikastellhorn:

Ideas for discussion were introduced with the following slides:
[[File:Background ideas.pdf|thumb]]

Short overview from discussions/breakouts:
* Background subtraction is dependent on:
** sample system/geometry/the observable physics.
* Each system has to be treated in a different way.
* A survey will help identifying the necessary / common steps among the community for specific classified systems.
* In case of multiple scattering: Include McStas as standard for GISANS analysis?

Notes:
* How do you know which type of (multiple coh/incoh.) scattering exists? And then which model for background to use accordingly? Are there approximations?
* always use multiple terms of the DWBA approximation? Where to draw the boundary?
* should we aim at always including a ray tracing approach (like McStas) to consider multiple scattering effects? (see union components McStas): https://mads-bertelsen.github.io/tutorial/Union_tutorial_1_processes_and_materials.html
* this all would strongly affect fitting of GISANS - we guess that this is one reason that no fitting of GISANS exists at the moment?
* typical approach of subtracting background doesnt work if it comes from "the sample itself, i.e., by multiple scattering in the sample"
* can this be "tested" how much the sample affects the background, are there test samples for comparison?
* why not the "typical approach": you subtract the instrument background (has to be well known), and all other "background" has to be from the sample and has to be simulated/fitted? this has then to be known for all wavelength bands and incident angles
* comparison to QENS where signals are always weak - how is that handled? Can what is known from there be taken over? QENS: Start with approximations for the model, and this then has to be refined. Also there the precise knowledge of the sample and the estimations of multiple scattering involved have to be taken into account!
* measure multiple states / dispersions / other observables to decrease ratio (unkown parameters)/(measured parameters)
* how to judge if the simulation (even if fitting perfectly to the data) is the physical correct one? For the question of which parameters are influencing the cross section mostly using bayesian fitting: see papers from Josh (for reflectometry): https://journals.iucr.org/j/issues/2021/04/00/ge5096/ge5096sup1.pdf

*****
group 1

Notes:
Alexandros: going to a corner and measuring bkg

Philipp: this corner you go is below/or above the horizon?
Alexandros: below.

Philipp: below the horizon, you have negative intensities. the corner will be different below or above the horizon.

Alexandros: yes, because you have something that absorbs and scatters at the same time.

Philipp: better to take it below the horizon instrument background.

Alexandros: problem we had usually with bare substrate, we had no other way to estimate bkg.

JF: the incoherent signal you get is not as constant in angle as you expect.

SJ: in GISANS, closer to footprint, after 2 cm is all incoherent.
JF: and inelastic
SJ: instruments masuring reflectometry and GISANS, first you scan through angle (and identify critical edge).
then, use this approach to get average SLD of the sample. problem with this approach would be that no SANS instrument can use this approach. put sample in, first reflectometry (get SLD) and afterwards then GISANS.

intensity and wavelength

Henrich: a SANS machine can do everything a reflectometry machine can do.
Philipp: can cover some angular range to see total reflection.

JF: Yes, but with poor resolution, for subtle variations of SLD this maybe not possible. we try to measure reflectivity curves when we do GISANS measurements.

SJ: is always worth it.

/Notes How to go forward

2026-03-18T17:16:05Z

Annikastellhorn: Created blank page

/GISANS Data Reduction and Analysis Upgrades Initiative

2026-03-18T17:15:20Z

Annikastellhorn: