A Monte Carlo analysis of neutron thermalization in graphite

The 250 Kev Cockroft - Walton accelerator currently under construction at Virginia Polytechnic Institute is to be used as a pulsed neutron source. The time dependence of neutron flux, energy spectrum as a function of time, and various reactor parameters such as Fermi Age, slowing dotm time, and diffusion length in graphite will be measured using the pulsed source method.

This thesis is a Monte Carlo calculation of the results to be expected in such an experiment. The neutron flux and energy spectrum was calculated at 1, 2, 5, and 10 microseconds after a burst of fast neutrons. The neutrons were “tracked" to thermal and the Fermi Age and slowing down time were determined.