Absorption Corrections Spencer Howells 1 Basics 2 Paalman-Pings 3 Monte Carlo

Basics Neutron paths in and out Transmission exp(-n*sigma*l) Scattering point Neutron paths in and out Transmission exp(-n*sigma*l) measured, calculated Input Shape – flat plate, cylinder, annulus Sample parameters – cross-sections & density Wavelength – for both paths Scattering angles

scattering absorption As,s sample sample Ac,c container container Paalman-Pings Takes into account both sample and container scattering absorption As,s sample sample Ac,c container container As,sc sample sample & container Ac,sc container sample & container Correction is (sample – container*Ac,sc/Ac,c)/As,sc Could extend to sample environment Sample volume divided up Input from diffraction, indirect with elastic, direct

Only calculates As,s and Ac,c Applied as an approximation Monte Carlo Scattering point generated at random Added beam size Only calculates As,s and Ac,c Applied as an approximation Awaiting version for P-P