SAAF: small-angle neutron scattering data analysis using analytical functions

SAAF is a tool for analyzing small-angle neutron scattering (SANS) data using analytical model functions. It is implemented in Perl and uses Gnuplot as its engine for curve fitting and data display. A set of standard models is provided with the program. New models are easy to implement at the user level. One of its features is the ability to perform de-smearing on data sets with variable and convoluted instrument resolutions. For SANS experiments, data de-smearing is often required, especially for data with small neutron scattering vector (Q) values or sharp scattering features. On time-of-flight instruments, the uncertainty in Q is a convolution of the contributions from neutrons with different wavelengths and beam intensities. SAAF is designed to take such Q resolution into account for data de-smearing. The program is part of the tool set offered at the EQ-SANS diffractometer at the Spallation Neutron Source. It is available in source form and is portable to multiple computer platforms.