Energy distribution and yield of neutrons from the (p,n) reaction in thick LiF targets

Abstract

The zero degree yield and the energy spectra have been investigated of neutrons being produced by protons of E p ⩽ 7 MeV in a thick natural LiF target, both experimentally by applying time-of-flight measurements and by a Monte Carlo simulation. While the experimental neutron energy spectra are disturbed by the neutron detector efficiency and by the finite time resolution of the apparatus (pulsed proton beam, time resolution of the neutron detector) the Monte Carlo simulation produces true energy spectra reflecting the energy dependence of the 7Li(p,n) cross section folded with the proton energy loss and beam energy uncertainty. The calculation correctly reproduces the experimental data for proton energies below E p ⩽ 3 MeV, where competitive reactions do not contribute to the neutron yield. This agreement justifies a simulation-based monitoring of the neutron flux and the neutron energy distribution from a thick target.