Quantitative explanation of the position and profiles of the (n, α) and (n, p) lines observed in a Si detector irradiated with fast neutrons

Abstract

The position and profile of (n, p 0.1) and (n, α 0) peaks produced by 14.5 MeV neutrons in a Si surface barrier detector have been measured and compared to theoretical predictions. The pulse height defect due to the nuclear interaction of the alphas and recoil nuclei with silicon have been taken into account as well as the differential cross sections dσ/dω for the respective reactions. Good agreement between data and calculations is obtained for an isotropic angular distribution of protons and a forward-peaked angular distribution for α-particles. The results indicate the limits of the use of Si surface barrier detectors as neutron spectrometers.