Reproducibility and Reliability Working Group

Reliability and Reproducibility

The group considers the issues that relate to reliability of results from small-angle scattering experiments, both as regards measured data and the parameters derived from analysis of the data that describe the samples. It had been established originally under the name 'Standardization' but has been renamed to provide a better description of the activities.

Anybody that is interested is welcome to join the mail group associated with this topic. Past messages are available at: https://groups.google.com/forum/#!forum/cansas-rrwg and there is a button marked 'Apply to join group'.

Members

• John Barker (NIST)
• Peter Boesecke (ESRF Contact)
• Jan Ilavsky (APS)
• Adrian Rennie (Uppsala University - chair)

News/Status

• December 2023. Finally, following on discussion at both canSAS-VIII in Japan and canSAS-X at Berkeley, a new Q standard for SAXS has been developed at NIST which will be available as an SRM by Joseph Kline. In a next step we are aiming to organize a round robin with this standard in 2024. More details will be on the round robin page as they become available.
• June 2017. There is discussion of new activities at the canSAS-IX meeting related Reproducibility and Reliability. http://www.cansas.org/wgwiki/index.php/Reliability
• August 2015. The mailing list is now on Google Groups https://groups.google.com/forum/#!forum/cansas-rrwg. A summary of recent activities will be presented at the lunch time session at the SAS2015 meeting in Berlin on Monday, September 14, 2015.
• A short account of the discussion concerning this topic at the canSAS-VIII meeting from 14 to 16 April 2015 in Tokai is available:

Discussion_Group_B2

Plans are being made (April 2015) for further types of sample to be circulated for comparative measurements.

• Discussion at the workshop in Uppsala has been presented on a separate page:

canSAS 2012 meeting discussions

• Work was presented at the SAS-2012 conference (www.sas2012.com). This includes a summary of standardization in the canSAS session and a presentation on the latex round robin measurements.

canSAS at the SAS-2012 Conference

Glassy Carbon Round Robin

Two samples of glassy carbons from Jan Ilavsky have been doing the rounds. They've been to NIST, ILL, ISIS, APS, ESRF and Diamond and ANSTO.

Details and data here : Glassy Carbon Round Robin

Polystyrene Latex Round Robin

Samples of a monodisperse polystyrene latex have recently been measured at ILL (D22 and D11), ANSTO (Quokka), ISIS (SANS2D) and at NCNR (NG7). Samples are also at Diamond awaiting measurement. Details and data here : Latex Round Robin

A new series of samples designated J, K, L and that have slightly different dilution have been provided for measurements at APS, FRMII, SPRING-8 and ILL.

Results of measurements with some conclusions are described in a publication in Journal of Applied Crystallography:

A. R. Rennie, M. S. Hellsing, K. Wood, E. P. Gilbert, L. Porcar, R. Schweins, C. D. Dewhurst, P. Lindner, R. K. Heenan, S. E. Rogers, P. D. Butler, J. R. Krzywon, R. E. Ghosh, A. J. Jackson and M. Malfois 'Learning about SANS instruments and data reduction from round robin measurements on samples of polystyrene latex', Journal of Applied Crystallography, 46, (2013). doi: 10.1107/S0021889813019468 [1].

Al ceramics masks

In 2019, during CanSAS workshop, we (Anna Sokolova [2] and Brian Pauw [3]) have had a discussion on a potential standard for SAXS/SANS measurements.

Al ceramics samples (masks) have been purchased from Smart membranes [4]. This material (it is also called 'Alumina membranes') has been used as an example for the SAXS/USAXS instrument testing, see B. R. Pauw, A. J. Smith, T. Snow, O. Shebanova, J. P. Sutter, J. Ilavsky, D. Hermida-Merino, G. J. Smales, N. J. Terrill, A. F. Thunemann, and W. Bras 'Extending synchrotron SAXS instrument ranges through addition of a portable, inexpensive USAXSmodule with vertical rotation axes'. Journal of Synchrotron Radiation, 28, (2021). doi: 10.1107/S1600577521003313 [5]. The material was also used in the study by A. Yildirim, K. Sentker, G. J. Smales, B. R. Pauw, P. Huberb, and A. Schonhals 'Collective orientational order and phase behavior of a discotic liquid crystal under nanoscale confinement'. Nanoscale Advances, 1, (2019). doi: 10.1039/c8na00308 [6].

SAXS data have been collected at ... and look promising, showing several peaks.

SANS data have been collected on Bilby instrument [7], ANSTO, using time-of-flight settings. Unfortunately, it appears that Al ceramics is not a good material to use because of asymmetry in the membrane and massive multiple scattering, visible even at 4.5A wavelength. In any way, we found it useful to present Bilby data here, for future reference.

Details and data here : Al Ceramics

Calibration Procedures

We will try to gather summaries of the procedures used for calibration of small-angle scattering instruments. It has been suggested that summaries of information would benefit both users and those who run instruments and facilities. Everyone is encouraged to contribute to this work in progress. Procedures for laboratory instruments as well as synchrotron and neutron facilities are welcome.

Details are here : Calibration Procedures

SESANS Working Group

In 2021, a sub-working group was formed dedicated to issues of reproducibility and reliability of spin-echo SANS (SESANS) measurements.

Details are here : SESANS Reproducibility Working Group