Thermal neutron cross sections for moderator materials: comparison of a synthetic scattering function and NJOY results

The Synthetic Scattering Function (SSF) allows a simple description of the incoherent interaction of slow neutrons with di€erent materials, especially hydrogenous ones. The main advantages of this model reside in the analytical expressions that it produces for double- differential cross sections, energy-transfer kernels, and total cross sections. We have included the SSF routines into the NJOY code, in such a way that the cross sections can be generated with the same format either from its standard library (ENDF/B-VI) or from our synthetic model. In this work we review the SSF results for the cross sections and scattering kernels for water, liquid methane and liquid hydrogen, and compare them with the data produced with the latest NJOY version and ENDF/B-VI library, and with experimental data when available