Capture of Negative Muons by Nuclei

Abstract

An experiment conducted to obtain precise values for the rates at which negative muons are captured by nuclei is described. These capture rates were deduced from muon disappearance rates measured by determining the time distribution of electrons resulting from the decay of muons in their lowest atomic orbit. 30 elements were investigated, using scintillation counters as detectors. The data are compared with the general theory of Primakoff and the specific predictions of Tolhoek and Luyten for nuclei with $20\le Z\le 28$. Primakoff's predictions for the effect of the Pauli principle are well borne out by this experiment, and the inferred capture rate of muons by protons is in good agreement with the hypothesis of a universal Fermi interaction. New values of effective nuclear charge densities (analogous to Wheeler's ${Z_{\mathrm{eff}}}^4$) were computed for analyzing the data, using a recent muon mass and up-to-date experimental information on charge distributions (from electron scattering and mesonic x-ray work). These new values are presented in tabular form.