/Normalization

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?