round robin

Rjkline — Fri, 05 Jun 2026 14:45:16 GMT

Planning Thoughts

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	==Members==		==Members==
	* Joseph Kline (NIST - chair)		* Joseph Kline (NIST - chair)
			* Caitlyn Wolf (NIST)
	* Adrian Rennie (Uppsala University)		* Adrian Rennie (Uppsala University)
	* Paul Butler (NIST - temporary?)		* Paul Butler (NIST - temporary?)
	* Others TBA		* Others TBA

	~~==Planning Thoughts==~~		Round robin consists of a tungsten grating calibration sample and three "unknown" block copolymer samples with different characteristic length scales. The round robin is blinded so that participants do not know the exact pitch of the tungsten grating calibration sample. The round robin will test current calibration methods used by beamlines and the improvement of calibration obtained by using the new calibration sample.
	* Shipping a ~~valuable~~ sample ~~internationally without incurring taxes will require some careful planning/ thought~~. ~~It may be easiest to ship back and forth from a central place (NIST seems~~ the ~~most natural in this case) rather than actually pass~~ the ~~same artifact around directly? Also arrange for return shipping as part of shipping?~~
	* Need to develop protocol to send to each participant. ~~How well the protocol works~~ will ~~help in refining~~ the ~~final protocol sent with~~ the ~~artifact~~. ~~Protocol should probably include:~~		Round Robin Process
	** ~~calibrate instrument in usual way~~		* Sample set consisting of tungsten grating calibration sample and three "unknown" block copolymers
	** measuring a ~~standard nanoparticle~~ sample		** Five similar sample sets will travel between facilities. Each set is slightly different, but pitches are known by NIST
	** ~~measuring~~ the ~~artifact using a rocking curve~~ to ~~ensure~~ a ~~proper measurement~~		* Participants will receive a sample set, conduct their normal calibration measurement, measure the tungsten grating sample like they would measure a calibration sample, then measure the unknown block copolymer samples
	** measuring the artifact rotating around the center point to ~~get Qx and Qy on~~ the ~~detector~~		* Participants will report their results and estimated values of grating pitch and block copolymer length scales using their normal calibration
	** position accuracy of ~~1mm is probably good enough~~		* Sample set will be returned to NIST and then sent to next participant
	** rotational accuracy of 0.~~1 degrees is probably sufficient~~		* NIST will compile results and send participants the pitch of the grating sample that they measured to recalibrate their measurements
	** return measured pitch.		* Final results will be combined into a publication

			Round Robin Details
			* 34 SAXS beamlines have responded to invitation to participate in the round robin
			* First sample sets were shipped out on June 4, 2026 with goal of completing the round robin measurements in the calendar year 2026
			* If interested in participating in the round robin, please contact saxs@nist.gov
			* The current calibration sample is optimized for SAXS. An additional calibration sample is being developed with much large area pattern for neutron scattering

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round robin