Comparison of Nuclear and Gamma-Ray Energy Scales

Cylindrical and spherical electrostatic analyzers have been used to measure the ratio of the threshold proton energy for the Li⁷(p, n)Be⁷ reaction to the Q of the Mg²⁴(p, p^')Mg24* reaction. This ratio was found to be 1.3734±{}0.0007. The energy of the gamma ray from Mg24* 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 (Au¹⁹⁸-Caltech) or proton-moment calibrated magnetic field (Co⁶⁰-Lindstrom et al.). The present data fix the Li(p, n) threshold as 1881.4±{}1.1 kev in terms of the Caltech value for the Au¹⁹⁸ gamma, or as 1879.7±{}1.1 kev in terms of the Lindstrom et al. value for a Co⁶⁰ gamma ray. The former value is in better agreement with currently used nuclear energy scales.