Prompt Fission Neutron and γ Correlations

Prompt neutrons and γ rays emitted shortly after scission provide valuable information to constrain fission physics models and their parameters. Numerical results obtained with event generators that simulate the de-excitation of the primary fission fragments can indeed be directly compared to various post-scission observables. The CGMF code implements the Hauser-Feshbach equations in a Monte Carlo approach to simulate the decay of the primary fission fragments that are produced in various configurations in energy, spin and parity. The neutron and decay channel widths are computed at each stage of the decay chain, thereby following successive emissions of particles on an event-by-event basis. Experimental as well as theoretical studies of correlations among the emitted particles shed some light on the mechanisms of excitation energy sorting at scission, the production of angular momentum in the fission fragments, and on the statistical nature of the fission fragment decay. Nuclear spectroscopy of the fission fragments is crucial for the accurate prediction of isomeric ratios and late-time promptγ-ray emissions. The CGMF code was recently integrated into the MCNP6.2 transport code, providing new and powerful tools for the interpretation of complex experimental data.