Neutron Spectra Determination by Resonance Reactions

The radiative capture of unidirectional neutrons by the individual components of a stack of cadmium-covered gold foils was investigated for several spectra, principally those obtained by various modifications of the emission from a ²⁵²Cf source. The relative experimental activation of the foils was empirically described by a simple three-group relation reflecting capture in the 5-eV resonance, the 60-eV resonance, and an “average” of other capture regions. The incident fluxes in these respective regions could then be identified, and it was shown that the relative activations of the individual foils due to neutrons in these three energy regions depended on the incident spectrum. The energy dependence of the flux in the 5- to 60-eV range was also empirically shown to depend on the neutron spectrum.