Fast neutron spectroscopy with solid state detectors

A polyethylene proton radiator placed in front of a solid state detector was used for fast neutron spectroscopy. Protons scattered at small forward angles were detected, giving a resolution of 270 keV for neutrons of 6 MeV. The possibility of using internal (n, p) and (n, α) reactions in the silicon of the detector for fast neutron spectroscopy has been investigated. A resolution comparable with that observed for direct detection of charged particles was obtained. For neutrons in the region of 6 MeV, the cross-sections were found to be of the order of 50 millibarns. The construction of a detector made of Si29 separated isotope is suggested. The reaction Si29(n, α)Mg26 resonates at En=5.35 MeV, indicating a level of 15.96 MeV in Si30/