This will be based on directly sampling S(a,b) data from the ACE format given as equiprobable cosine and outgoing energy bins for a given incoming energy. Interestingly, MC21 empoys a direct S(a,b) sampling method whereby the original ENDF data tabulated on an a,b mesh is turned into pdfs p(b|E,T) and p(a|b,E,T) which can be directly sampled in the MC simulation. This eliminates some non-physical effects (observed by Bjorn Becker). See Clint Ballingers 1995 M&C paper.
This will be based on directly sampling S(a,b) data from the ACE format given as equiprobable cosine and outgoing energy bins for a given incoming energy. Interestingly, MC21 empoys a direct S(a,b) sampling method whereby the original ENDF data tabulated on an a,b mesh is turned into pdfs p(b|E,T) and p(a|b,E,T) which can be directly sampled in the MC simulation. This eliminates some non-physical effects (observed by Bjorn Becker). See Clint Ballingers 1995 M&C paper.