Neutron polarization in the T(d, n)He 4 reaction at Ed = 2.1 and 2.9 MeV

Abstract

The angular distributions of the polarization of the neutrons from the T(d, n)He 4 reaction have been investigated at incident deuteron energies of 2.1 and 2.9 MeV. The asymmetries of the neutrons scattered by helium have been determined by measuring the energy and the direction of the recoil α-particles by means of a counter telescope consisting of two parallel-plate avalanche counters. The measurements have been performed in open geometry. The angular distributions of the polarization show maximum values at σ n lab = 75° of P = −(16.9±4.0)% and P = −(19.2±4.6)% at E d = 2.1 MeV and 2.9 MeV respectively. In both cases a second zero crossing appears at σ n lab = 105° leading to positive values at backward angles. The experimental results are compared with previous measurements in the energy region of the deuterons from 1.8 to 10.0 MeV. The characteristic features of the angular distributions and the energy dependence of the polarization are discussed.