July 2026 - users - SasView Mailing Lists

SasView Size Distribution Model Convergence
by Jacob Barron 29 Jul '26

29 Jul '26

Hello, I am inquiring about the meaning of convergence from you size distribution model. I recently completed some SANS measurements on a low alloy steel and found the size dist model is not able to converge without increasing the weight factor. However the ChiSq value is quite low, almost one, and upon repeated fittings the resultant distributions are very similar, which is encouraging results and a distribution I would expect from these samples. [image: image.png] Increasing the weight factor to 1.5 allows the fit to converge. However I do notice that visually the curve fit worsens even though the ChiSq value is better. This convergence feels artificially forced to me, as my understanding is that this increases the error bars. I also notice this shifts the dominant size distribution slightly larger. Repeating this fit does not give a unique solution. [image: image.png] Would I be able to get an explanation on why the convergence matters here. I understand that the population is located on the boundary of the trust range, this is expected with this material, we are limited by the neutron wavelength in this case. Of course the reported volume fraction is to be taken with some uncertainty. Any help is appreciated. The file is attached, as is the raw data. Best regards, Jacob Barron, -- Jacob Barron, BSc, EIT PhD Candidate Materials Engineering University of Alberta

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Next Contributor Camp announced
by Paul Butler 17 Jul '26

17 Jul '26

Dear SasView community, It is with great pleasure that we announce the opening of registration for the XV SasView Contributor Camp to be held at Charles University in Prague, Nov 3-9 2026. This annual community event brings together members of the SAS community to work on improving the SasView tools, tutorials, and documentation that we all use. The final scope of the work is determined by the interests of those who attend but known points of interest/focus this time include the General Scattering Calculator (making it more user friendly while better supporting bioSAS needs), the sasmodels package, and improving support for hard condensed matter and diffraction workflows. Anyone interested in contributing to the SasView project (writing tutorials, documentation, coding, verifying the math/science, or undertaking sys admin tasks, etc) is welcome, even encouraged, to join. See the link below for the latest planning. This is an opportunity to come together to work on our common issues. The camp planning page can be found at: https://github.com/SasView/sasview/wiki/ContributorCampXV Registration is at: https://workshops.ill.fr/event/586/registrations/395/ We look forward to seeing many of you there Paul (for the SasView leadership team)

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SasView mailing lists moving to a new server this week
by Paul Butler via users 14 Jul '26

14 Jul '26

Dear SasView Users, Quick heads-up: sometime this week we'll be moving the SasView mailing lists (i.e., users, developers and help) onto a new server and upgrading from the old list software at the same time. The current server is well past its supported life and is being retired for security reasons. For almost all of you this will be invisible — the list addresses don't change and your mail keeps arriving as usual. A couple of things a few of you might notice: - Messages will now come from the new system, so they may look slightly different, and there is a small chance your mail provider might file the first one or two as spam. If that happens, just mark them "not spam." - If you'd set up a login to manage your own delivery settings, that login won't carry over — you'll need to register again on the new site (your list email address plus a new password). Everything else comes across automatically: all memberships and their delivery preferences, plus the full message archives — which are now searchable on the new system. Thanks for your patience during the move, and feel free to email help(a)sasview.org with any questions or concerns. Cheers Paul (for the SasView leadership team)

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Model building in sasview
by Harrison Laurent via users 02 Jul '26

02 Jul '26

Hello, I hope you are well. I am currently trying to build a reasonably complex model within sasview and have gone to the guide on how to manage this. I see in the documentation (SasView-6.1.3/sas/docs/user/qtgui/Perspectives/Fitting/fitting_help.html) that to achieve this one creates a 'simple' model combining two established models, then opens the model in the model editor. One can then add/multiply several different functions together by editing the text after 'load_model_info'. My question is how do I account for multiplying several summed models by a single other model, as brackets seemingly cannot be used. AKA how do I achieve the following sort of functions: (sphere + gaussian_peak + sphere)*user_defined_fractal_model ((sphere + gaussian_peak) + sphere)*user_defined_fractal_model ((sphere + sphere)*user_defined_fractal_model) + gaussian_peak Any insight you have would be extremely helpful. Thank you so much. All the best, Harrison Laurent

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