Comparison of Nuclear and Gamma-Ray Energy Scales

Abstract

Cylindrical and spherical electrostatic analyzers have been used to measure the ratio of the threshold proton energy for the ${\mathrm{Li}}^{7}(p, n){\mathrm{Be}}^{7}$ reaction to the $Q$ of the ${\mathrm{Mg}}^{24}(p, {p}^{\ensuremath{'}}){\mathrm{Mg}}^{24*}$ reaction. This ratio was found to be 1.3734\ifmmode\pm\else\textpm\fi{}0.0007. The energy of the gamma ray from ${\mathrm{Mg}}^{24*}$ has been compared earlier by Hedgran and Lind to other gamma rays whose energies have been measured absolutely by either the curved crystal spectrometer method (${\mathrm{Au}}^{198}$-Caltech) or proton-moment calibrated magnetic field (${\mathrm{Co}}^{60}$-Lindstrom et al.). The present data fix the $\mathrm{Li}(p, n)$ threshold as 1881.4\ifmmode\pm\else\textpm\fi{}1.1 kev in terms of the Caltech value for the ${\mathrm{Au}}^{198}$ gamma, or as 1879.7\ifmmode\pm\else\textpm\fi{}1.1 kev in terms of the Lindstrom et al. value for a ${\mathrm{Co}}^{60}$ gamma ray. The former value is in better agreement with currently used nuclear energy scales.