Experimental study of potential neutron moderator materials

We present an experimental investigation of thermal neutron energy spectra produced by lead and bismuth hydroxides (Pb(OH)2, and Bi(OH)3). The experimental energy spectra are compared with a thermal neutron energy spectrum produced by water measured in the same geometry. We developed an MCNPX geometry model designed to help with the interpretation of the experimental data. We demonstrate a very good reproduction of the experimental thermal neutron energy spectrum produced by the water moderator in our tightly coupled geometry. We study our experimental results for Pb(OH)2 and Bi(OH)3 using thermal neutron scattering kernels for hydrogen, bismuth, and lead.