Gas-Recoil Fast Neutron Spectrometer

Abstract

A gas‐recoil fast neutron spectrometer based on the collimation scheme of R. Giles has been constructed and its behavior analyzed. The principal effort has been directed to improving peak‐to‐valley ratio of the instrument. Electron capture has been minimized and anticoincidence end‐effect counters included in the present design. A graphical analysis has been made of the collimation scheme and the results predicted by the analysis compared with experiment. Li⁷(p,n)Be⁷ and D(d,n)He³ neutron groups have been observed using, in turn, palladium‐filtered hydrogen and pure propane as spectrometer fillings. Energy spreads of 10% and under with efficiencies exceeding 10⁻⁴ have been obtained with peak‐to‐valley ratios of 10 to 1. Neutron groups from the Be⁹(d,n)B¹⁰, C¹²(d,n)N¹³, O¹⁶(d,n)F¹⁷, and A⁴⁰(d,n)K⁴¹ reactions have been observed.