Development of NRD, 3; Study of a new moderator for compact 14-MeV pulsed neutron sources

Takamine, Jun ; Koizumi, Mitsuo ; Kureta, Masatoshi   ; Harada, Hideo   ; Kitatani, Fumito  ; Tsuchiya, Harufumi ; Seya, Michio; Iimura, Hideki  

A prototype device of neutron resonance densitometry (NRD) with a D-T neutron generator was planned for basic studies of actual NRD devices. D-T neutron generators had features of simple handling and compact compared with photo neutron sources driven by electron beam accelerators. But those of D-T neutron are higher energy and lower intensity than those of photo neutron. We designed a new type moderator to compensate for the shortcomings. In the new type moderator, the D-T neutron generator is surrounded by Lead, and Polyethylene is arranged in the beam direction on the surface of Lead. As the result of analysis using Monte Carlo code MCNP5, it was found that the new moderator achieved about four times larger production of low energy neutrons than polyethylene moderator without distorting the energy resolution below at least 100 eV. The lead part in the new moderator are changed to other heavy metals, which is Uranium, and Tungsten. Analysis like the above were performed. We report these results.