Production of source neutrons by low voltage accelerated deuterons on titanium - tritium targets

The detailed information on neutron source characteristics is important to meet the demand of research and applications on neutron activation and transport phenomena. Fast monoenergetic neutrons can be produced by two body reactions induced by accelerated particles. In a number of laboratories much progress has been made in producing intense neutron sources based on the Deuteron - Tritium reaction to study the interaction of 14 MeV neutrons with structural materials of fusion reactors, to increase the sensitivity of the activation analysis, to measure the low cross sections and to use them in neutron therapy. At present the MCNP family of codes cannot model the D - T reaction for Deuteron energies in the KeV range explicitly. The physical processes involved in the neutron generation were modelled by defining the SOURCE and SRCDX subroutines of the MCNP code. The properties of a neutron source from a D - T reaction were investigated, starting from the ENDF/B-VII nuclear data library for deuterons incident on a tritium target. The effects of the Titanium - Tritium atomic fraction, target thickness and deuteron energy on the source neutrons yields and energy were simulated. The angular and energy neutron distributions obtained from first principles were then applied to the MCNP5 simulation of the tungsten integral experiment performed at the Japanese OKTAVIAN 14 MeV neutron facility. The purpose of the work was thus to establish a pattern for the critical evaluation of a 14 MeV neutron source in modelling benchmark experiments. (author)