Method for Obtaining a Component of Approximately Collimated Fast Neutrons in a Reactor

摘要

By locating a uranium slug in the reflector of a graphite reactor, at the edge of the loading, an approximately collimated fast neutron flux is obtained which is at least twice the random background fast flux. The relative intensity of the collimated flux is determined by the separation between slug and sample. Close to the slug the directed flux is high and the collimation poor, and by increasing the separation, the collimation is increased but at the expense of intensity. The fast flux in the region where samples are located was determined using the U238 fast fission reaction. The spatial dependence of the directed flux can be approximated by an inverse square expression.