The Absorption of Resonance Neutrons by Boron, Chlorine, Cobalt and Manganese

Measurements are made of the absorption of neutrons by boron and by several elements which capture the neutrons without activity (or with very weak activity). Rh, In, Ag, Mn, Br and I were used as thermal and resonance detectors, and their known boron absorption coefficients were redetermined more carefully. The resonance levels of only Rh and In appeared to be single. It is shown that, by comparing the boron absorption coefficients with the absorption coefficients of the nonradioactive elements, resonance levels of those elements can be located: Resonances are found for Cl³⁶ near 1 volt, for Co⁵⁸ near 1 and 30 volts, for Mn below 0.4 volt. Corrections for nonparallelism of the neutron beam are made semi-empirically and neutron scattering by the absorbers is shown to be quite small compared to neutron capture.