Neutron Scattering, Measurements using the Associated Particle Technique

Abstract

The associated particle technique is applied to the D(d,n)3He reaction in order to produce a tagged neutron beam of accurately known energy, flux and direction. A neutron – 3He fast coincidence system with a timing resolution 4.5 nsec. (f.w.h.m.) is described. This system is utilised in a multidetector neutron time of flight spectrometer. The spectrometer is used to measure the absolute differential elastic and inelastic neutron scattering cross sections for 31P, 51V and 209Bi at a neutron energy of 2.4 MeV. The results obtained are compared with values obtained by other workers and with theoretical predictions. A comparison of associated particle and pulsed beam methods for neutron scattering measurements in the 2.5 MeV region is made.