Revisiting Elastic Scattering of D(n, n)D reaction

Abstract

Interest has risen recently c oncerning the angular distribution o f neutron elastic scattering on deuterium at low incident energies. The main subject is the amount of backscatter at energies below 3.2 MeV observed in differential cross-section measurements and represented in various evaluations. These various angles of approach encompass fundamental nuclear-data measurements, three-body nuclear-theory calculations, evaluated nuclear -data libraries and associated data processing, and the simulation of critical experiments involving heav y water. A new theoretical approach on the basis of three -nucleon theory was made that resulte d in new angular distributions. At the GELINA neutron time -of-flight facility a new experimental setup was developed to measure elastic scattering of neutrons on deuterium in the energy range of interest. The technique proposed is complementary to the earlier works by detecting the scattered neutron instead of the recoiling deuterium . The setup is an array of two HPGe detectors, each with a 10 B neutron-gamma converter. Preliminary GELINA findings using a C6D6 target indicate less backscatter than predicted by ENDF/B -VII.0, in contrast to the nuclear -theory results. It is expected that completion of the planned work will reduce the uncertainty of the energy-angle distributions for deuterium elastic scattering and contribute to an improved deuterium evaluation in a future release of ENDF/B -VII.