## Beta Approximation Work Package

Incorporation of the 'Beta Approximation' or 'Beta Correction' for S(Q) has long been identified as an important, yet often ignored, correction in model fitting. However, implementing it in SasView is non-trivial.

As of Summer 2018 we are starting to lay the groundwork, with the help of two vacation students, one in the US and one in the UK.

They will approach the implementation from both the bottom-up (changing the code kernel to compute amplitudes instead of intensities, etc) and the top-down (the UI, model parameterisation, choice of effective radius, etc).

As part of the implementation process, computations from SasView are also being validated against those from SASfit, FISH and Matlab.

### Tasks

- Understand exactly what the Beta Approximation calculation requires
- Figure out how the SasView 'middle layer' needs to change to implement the Beta Approximation calculation
- Decide how best to redesign the UI to allow a User to make use of the Beta Approximation calculation
- Decide how best to implement the Effective Radius (ER) of interaction in S(Q) calculations (may involve an overhaul of constraints in SasView)
- Provide unit tests
- Provide documentation

### Guiding References

*Analysis of small angle neutron scattering spectra from polydisperse interacting colloids.*M Kotlarchyk & S‐H Chen.*Journal of Chemical Physics*79, 2461 (1983) https://doi.org/10.1063/1.446055*A critical examination of the decoupling approximation for small-angle scattering from hard ellipsoids of revolution.*DG Greene, DV Ferraro, AM Lenhoff & NJ Wagner.*Journal of Applied Crystallography*49, 1734 (2016) https://doi.org/10.1107/S1600576716012929*SANS from concentrated dispersion.*S Kline.*NCNR Summer School. Neutron Small Angle Scattering and Reflectometry from Submicron Structures*. June 5 - 9, (2000) https://www.ncnr.nist.gov/programs/sans/pdf/sans_conc_disp.pdf

## Contributors

- Paul Kienzle & Greg Suczewski (student)
- Richard Heenan & Torin Cooper-Bennun (student)
- Yun Liu

- Paul Butler
- Wojtek Potrzebowski
- William Heller
- Steve King

## Tickets

## Milestone: SasView 5.0.0 (7 matches)