Measurement of prompt neutron capture gamma coming from iron and chlorine

Abstract

Prompt gamma radiation mostly comes from neutron reactions, thus naturally accompanying neutron transport. Therefore, it is an important part of the gamma field in nuclear installations, which accompanies neutrons leaking from the system. This also implies that good knowledge of the prompt gamma description of iron is essential in reactor dosimetry, especially as part of gamma heating and related issues. As the prompt gamma has a discrete character, it can be efficiently used in nuclear forensics for the identification of various isotopes. Prompt gamma rays from neutron capture on iron and chlorine were measured using HPGe and stilbene detector. Iron (as FeSO4) and chlorine (as NaCl) were dissolved in water to maximize the thermalization process of 252Cf(s.f.) neutrons emitted from acentrally positioned neutron source in the solution tank. Not only iron and chlorine peaks were found in the HPGe spectra, but six sulfur peaks from ferrous sulphate were identified as well. The experiments were simulated with the MCNP6.2 code using the ENDF/B-VIII.0, JEFF-3.3 and JENDL-5 libraries. Peak comparisons using HPGe results were generally discrepant in all libraries. Astudy of prompt gammas from thermal neutron capture reveals significant differences between the libraries studied. The comparison of whole spectra using stilbene results shows discrepancies in the gamma production data for chlorine in all libraries. Calculations with FeSO4 give quite good results for JENDL-5 and ENDF/B-VIII.0 and discrepant results for JEFF-3.3.