The work and the discussion of the standards group centered on four themes:
Planning and preparation of dissemination to encourage exploitation of previous results such as round-robin measurements.
- Studies should result in publications in refereed journals. This is important for community acceptance and to reach a wide audience.
- Facilities and users should learn about best practice by publishing recommendations and the web portal should point to papers and to other documents that describe the best practicesidentified by comparison between laboratories.
- Specific plans for publication on round-robin measurements on glassy carbon samples and on latex have been prepared and discussion between the authors started
Future Projects and Plans
Planning future co-operative measurement activities - round robin 'standards'. In this area it was felt that not too many new projects could be initiated at one time. It is probably most efficient if they start with work at just two or three facilities. When an appropriate sample or samples have been prepared and initial data collected, these can be broadened to include a wider range of participants.
- Several fields were identified as likely to benefit from new round-robin activities. In practical terms it was thought best to initiate only two or three new projects immediately and that these should first be started by a small group of two or three participants. They can then be widened when initial materials and data are available.
- Grazing incidence scattering was seen as one priority for production of a reference sample suitable for both X-ray and neutron studies.
- Biological small-angle scattering would benefit from appropriate 'standard' samples that are understood by that community of users and are appropriate to measure in instrument configurations that used by that community.
In the longer term it will be useful to initiate a project that can involve anomalous X-ray scattering and further samples to allow quantification and tests of the influence of resolution.
Uncertainties and Reliability
Major discussion concerned the importance of uncertainty in SAS measurements: both statistical counting errors and systematic deviations.
- Previous studies, particularly with the latex round-robin sample have identified that systematic errors are frequently more significant than the random errrors that arise solely from counting statistics. This needs to be more widely recognised in publications, data analysis procedures and even in guidelines for good practice.
- A longer term project to evaluate systematic errors and the uncertainty that derives from them is desirable. This will need gathering a group of appropriate people and invitations are being prepared.
Interaction with other canSAS activities
The group interacts closely to present appropriate ideas on standardisation and reliability topics to the other canSAS groups.
- Several of the ideas that have been discussed relate closely to work in other groups. New data formats should facilitate better description of uncertainty, the systematic recording of appropriate sample metadata and their uncertainties and the the reduction and analysis.
- The web portal should clearly identify good practices and provide appropriate training and educational material.
At the meeting specific activities were planned:
- Possible fabrication of a patterned substrate for intercomparison of grazing incidence scattering will be investigated (Sarah Rogers) and circulated for discussion.
- Groups that have been involved in the latex Round-Robin have been contacted to obtain necessary complementary information for a publication (Adrian Rennie). It was considered desirable that at least one X-ray data set be included in the publication if possible.
- The glassy carbon Round-Robin samples are being returned to Europe (from ANSTO) for further measurements of neutron transmission as a function of wavelength and inelastic scattering at ISIS and ILL. These are scheduled for September 2012.
- ANSTO and ISIS are sharing information about proteins as standards and for intercomparison.