J.C. Young

Neutron-Spectrum Measurements in H 2 O, CH 2 and C 6 H 6

AbstractNeutron-spectrum measurements in several moderators have been made with geometrical conditions approximating an infinite medium. The moderators studied were water, polyethylene and benzene, and the absorbers dispersed in the moderators were boron, samarium, erbium and gadolinium. The measurements are compared with predictions of the neutron spectra utilizing scattering models which take into consideration chemical binding. Measurements of scalar and angular neutron-energy spectra were made in a slab geometry water-moderated multiplying assembly at room temperature. The measured spectra are compared with DSN transport-theory calculations utilizing the Nelkin bound-hydrogen scattering model for water.

Neutron Thermalization in Zirconium Hydride

Molecular models used to explain neutron thermalization in zirconium hydride are reviewed, and results obtained with the models are compared with recent experimental results. The Einstein oscillator model and the phenomenological description of Miller each explain some of the data, but they predict the temperature dependence of the neutron spectra quite differently. This dependence for zirconium hydride poisoned with boron was measured by time-of- flight means. The spectrum was found to shift markedly with temperature, almost as predicted by the Einstein models. (D.C.W.)