Late Prompt Fission Gamma Rays from 235U(n,f) and 252Cf(sf)

Two measurements of fission γ rays were performed with the DANCE and NEUANCE arrays using the reactions 235 U(n, f ) and 252 Cf(sf). Utilizing the fast time response of the detectors and a method for estimating the accidental background, we obtained the energy spectrum of the late prompt fission γ rays as a function of the time since fission. The experimental results are compared with predictions of the code CGMF folded with GEANT4 simulations of the detector response.