FAST NEUTRONS FROM THE T + D AND T + Li REACTIONS

Abstract

The fast neutrons produced by the triton bombardment of LiF, Li2CO3, LiOH∙H2O, LiOD, and LiOD∙D2O + D2O have been detected, and the thick target yields and their slowing down lengths in graphite measured. The tritons were produced by irradiating the compounds in the high thermal neutron flux of the thermal column of the NRX pile. The spatial distributions of the fast neutrons from the T + D and T + Li reactions were measured in the graphite with indium resonance detectors. The numbers of fast neutrons emitted per second were obtained by comparing the space integrals of the indium activity with that measured when a standard Ra-α-Be source of neutrons was in the position of the lithium compounds. The number of incident tritons was estimated from the measured flux of thermal neutrons at the lithium compound and the total capture cross section of the lithium. The thick target yields were thereby derived. The average cross sections for neutron production by 2.6 Mev. tritons are 1.5 × 10−24cm.2 per atom of lithium and 0.41 × 10−24cm.2 per atom of deuterium. The slowing down lengths in graphite of density 1.64 gm. per cc. are 19.2 and 23.4 cm. for the neutrons from the lithium and deuterium respectively. The smallness of the latter indicates that inelastic scattering of these 14 Mev. neutrons occurs in graphite.