Development of a gaseous recoil-proton detector for neutron flux measurements between 0.2 and 2 MeV neutron energy

P Marini,J.L Pedroza,L Mathieu,B Jurado,S Czajkowski,T Cheron,I Tsekhanovich,M Aiche,P Hellmuth

doi:10.1051/epjconf/201714603015

Abstract

Absolute measurements of neutron fluence are an essential prerequisite of neutron-induced cross section measurements, neutron beam lines characterisation and dosimetric investigations. Precise neutron flux measurements can be performed with respect to the H(n,p) elastic cross section. The use of this technique, with silicon proton recoil detectors, is not straightforward below incident neutron energy of 1 MeV, due to a high background in the detected proton spectrum. Experiments carried out at the AIFIRA facility identified its origin. Based on these investigations, a gaseous recoil-proton detector has been designed, with a reduced low energy background. Preliminary results of the first tests of the developed detector are discussed here.

Highlights

Absolute measurements of neutron fluence are an essential prerequisite of neutron-induced cross section measurements, neutron beam lines characterisation and dosimetric investigations
Precise neutron flux measurements can be performed with respect to the H(n,p) elastic cross section
Fission cross section measurements have to be improved in the 0.1–1 MeV energy range [4]

Summary

Silicon-based recoil-proton detector

The development of Generation IV nuclear systems relies on accurate simulation based on high quality nuclear data [1]. The neutron flux is determined with respect to well-known fission standard reactions (235U(n,f), 238U(n,f), 237Np(n,f)) This introduces a strong correlation between independent measurements based on the same standard. Independent measurements can be carried out with respect to the H(n,p) elastic cross section In this method, the neutron flux is converted into a proton flux, by mean of a H-rich foil. A proportional counter protonrecoil spectrometer filled with hydrogen and allowing neutron/γ (electrons) discrimination was developed in the 60’s by Bennett et al [5] The comparison to this detector of the newly developed gas detector is discussed in the c The Authors, published by EDP Sciences. Following, despite the different scopes of the two detectors (neutron energy spectra vs neutron flux measurements)

A gas recoil-proton detector prototype

Performances

Findings

Conclusions