A Resonance Process in the Disintegration of Boron by Protons

Abstract

An experimental investigation of the efficiency of production of $\alpha$-particles from boron as a function of the energy of the bombarding protons is reported. Of the two established processes, ${}_5{}^{}{}_{}{}^{}\mathrm{B}_{}^{11}{}_{}{}^{}+{}_1{}^{}{}_{}{}^{}\mathrm{H}_{}^1{}_{}{}^{}\to 3{}_2{}^{}{}_{}{}^{}\mathrm{He}_{}^4{}_{}{}^{}+Q_1$ and ${}_5{}^{}{}_{}{}^{}\mathrm{B}_{}^{11}{}_{}{}^{}+{}_1{}^{}{}_{}{}^{}\mathrm{H}_{}^1{}_{}{}^{}\to {}_4{}^{}{}_{}{}^{}\mathrm{Be}_{}^8{}_{}{}^{}+{}_2{}^{}{}_{}{}^{}\mathrm{He}_{}^4{}_{}{}^{}+Q_2,$ the second exhibits peculiarities in its efficiency curve whereas the first increases exponentially with proton energy. This irregularity is interpreted as the occurrence of a resonance process in the second disintegration, the resonance peak occurring at 180 kv. A discussion of the possible theoretical interpretations of the process is given. Absolute yields for a thick boron target at various proton energies are given.