Published 2014
NDS Staff Publication
Elastic and inelastic scattering of neutrons on 238U nucleus
- 1. Nuclear Data Section, IAEA
Description
Advanced modelling of neutron induced reactions on the 238U nucleus is aimed
at improving our knowledge of neutron scattering. Capture and fission channels are well
constrained by available experimental data and neutron standard evaluation. A focus
of this contribution is on elastic and inelastic scattering cross sections. The employed
nuclear reaction model includes – a new rotational-vibrational dispersive optical model
potential coupling the low-lying collective bands of vibrational character observed in
even-even actinides; – the Engelbrecht-Weidenmüller transformation allowing for inclusion
of compound-direct interference effects; – and a multi-humped fission barrier with
absorption in the secondary well described within the optical model for fission. Impact
of the advanced modelling on elastic and inelastic scattering cross sections including angular
distributions and emission spectra is assessed both by comparison with selected
microscopic experimental data and integral criticality benchmarks including measured
reaction rates (e.g. JEMIMA, FLAPTOP and BIG TEN). Benchmark calculations provided
feedback to improve the reaction modelling. Improvement of existing libraries will
be discussed.