Differential and Integral Measurements of an Intermediate Neutron Spectrum

Abstract

The neutron spectrum in an intermediate neutron system composed of C, B and AI was measured by two methods: one based on TOF (time-of-flight), which aims at establishing the system as a standard or reference neutron spectral field, and the other the l/w-filter difference method which is a new departure. In the latter method, a set of count rates obtained with a small BF3 counter sheathed in 10B-filters of different thicknesses is unfolded into the neutron spectrum. Two successful unfolding methods, i.e. least-squares series expansion and count rate iteration, are demonstrated. By the TOF method, the neutron spectrum is determined in detail with satisfactory accuracy, while by the other method, a rough outline of the neutron spectrum under IkeV is obtained. Some discrepancy is found between the TOF and the theoretical results. It is concluded that the 1/v-filter difference method is useful as an easy method of estimating an intermediate neutron spectrum.