Measurements of Deviation from 1/E Distribution in Epi-Cadmium Neutron Spectrum

Abstract

Although the neutron spectra in the epi-thermal region in thermal reactors are usually assumed to be of 1/E distribution, it is important in some cases to consider the deviation of the distrtribution from the 1/E shape. In this paper an approach to the representation of the reaction rate of the epi-cadmium energy neutron is presented, and a characteristic parameter defining the deviation from the 1/E shape is introduced. This parameter is useful in studying the spatial dependence of epi-cadmium neutron spectra in thermal reactors. It is shown that a ²³⁵U fission detector is one of the best detectors for this purpose. The measurement involved was performed by using a ²³⁵U fission counter in the SHE critical assembly. The experimental results obtained are compared with theoreticalresults, and the agreement between the two is good.