The Capture of Orbital Electrons by Nuclei

The simple theory of electron capture is outlined and three general methods for its detection are suggested. The first experimental evidence for the process (in activated titanium) is described. A rigorous experimental proof of the hypothesis is given for the case of ${\mathrm{Ga}}^{67}$. A summary of several isotopes whose properties are best explained on this hypothesis is appended. The properties of ${\mathrm{Ga}}^{67}$ are described in considerable detail, and include the first evidence for internal conversion in artificially radioactive atoms.