id summary reporter owner description type status priority milestone component resolution keywords cc workpackage 743 Consider revising the SESANS data format read by SasView wimbouwman wimbouwman "After discussion with some of you, especially Joachim, I’m getting more convinced that we should redefine the input format for SESANS measurements in !SasView. SANS the users provide their data in absolute units to the data-analysis software. With SESANS we can do the same thing by using ln(P(z))/t*(lambda2) as a function of the spin-echo length. There are several advantages of using the SESANS in absolute units in the data format: · This way we can already directly compare data measured at different instruments with different thickness samples. · In the software we don’t have to worry about monochromatic of TOF measurements. · In the software only two columns are needed P and z (in analogy with SANS I and q). This makes it much easier to work with the same software. This is something we meet right now with the architecture of the !SasView-code. · The responsibility of the conversion into absolute units is with the user in the data-reduction, just like with SANS. This avoids any ambiguity in parameter passing in the data-format to !SasView or !SasFit. · With fitting the contributions of components become linear, which is an enormous advantage if the analytical SESANS equations are available. This will make it possible to reuse many SANS parts of coding with multiple contributions and polydispersity. · The calculation of the Jacobian in the chi2 calculation is more effective. This idea is different from the idea we started to follow at the code camp in Feb 2015 in Copenhagen, where we thought it would be best to have the spin-echo length, the wavelength and the polarisation in the data-files. There are some drawbacks to the format with the SESANS in absolute units. · You present something further away from the primary data. It makes it more difficult to evaluate by eye the quality of fits. This can be circumvented with some extra work by a back transformation of the fit. · It could be more tricky to take into account the spread in wavelength for the amount of scattering. However, I have the feeling it won’t be to difficult mathematically to do this in the data reduction before the fitting. · We would have to change some of the earlier coding in !SasView and !SasFit. However, these changes are not difficult and will make further coding much simpler, more robust and reliable. Please let me know if you have any strong opinions about the SESANS data format. Untill Tuesday morning we are working on the code with all the experts of !SasView around the table. If you are positive about providing SESANS data in absolute units to the analysis software, then I’ll come with a new proposal for the format based on my discussions with you. Warm collegial regards, Wim" enhancement closed major SasView 4.1.0 SasView fixed SESANS Integration