Study of fission fragment de-excitation by gamma-ray spectrometry with the EXILL experiment

T Materna ,Michal Rapał A,A Marchix ,U Köster ,T Söldner ,O Sérot ,A Blanc ,A Letourneau ,P Mutti ,G S Simpson ,W Urban ,O Litaize ,M Jentschel ,C A Ur

doi:10.1051/epjconf/201714604041

Abstract

A large array of Ge detectors installed at ILL, around a 235 U target irradiated with cold neutrons, (EXILL) allowed measurement of prompt gamma-ray cascades occurring in fission fragments with an unambiguous determination of fragments. Here we present preliminary results of a systematic comparison between experimental γ-ray intensities and those obtained from the Monte-Carlo simulation code FIFRELIN, which is dedicated to the de-excitation of fission fragments. Major γ-ray intensities in the 142 Ba and 92 Kr fission products, extracted from EXILL data, were compared to FIFRELIN, as well as to reported values (when available) obtained with EUROGAM2 in the spontaneous fission of 248 Cm. The evolution of γ-ray intensities in 92 Kr versus the complementary partner in fission (i.e. versus the total number of evaporated neutrons by the fission pair) was then extracted and compared to FIFRELIN.

Highlights

A large array of Ge detectors installed at Institut Laue-Langevin (ILL), around a 235U target irradiated with cold neutrons, (EXILL) allowed measurement of prompt gamma-ray cascades occurring in fission fragments with an unambiguous determination of fragments
We present preliminary results of a systematic comparison between experimental γ -ray intensities and those obtained from the Monte-Carlo simulation code FIFRELIN, which is dedicated to the de-excitation of fission fragments
A large array of sixteen HPGe detectors was placed at the end of the PF1b cold neutron guide, which has the highest neutron flux at the ILL

Summary

Experimental details

A large array of sixteen HPGe detectors was placed at the end of the PF1b cold neutron guide, which has the highest neutron flux at the ILL. It included eight EXOGAM clovers, two smaller clovers from LOHENGRIN and six large efficiency detectors from GASP. Except the two LOHENGRIN clovers, were surrounded by a BGO active shielding to reduce Compton background. Its capture flux c The Authors, published by EDP Sciences. More details on the setup, the target assembly and the shielding can be found in [2, 4]

Analysis

Preliminary results

Conclusion and perspectives