Reaction ${\mathrm{A}}^{40}(p, n){\mathrm{K}}^{40}$ and the Decay of ${\mathrm{K}}^{40}$

The energy difference involved in the decay of ${\mathrm{K}}^{40}$ to ${\mathrm{A}}^{40}$ by electron capture was measured in two ways. First, a time-of-flight technique was used to observe the neutron spectra from ${\mathrm{A}}^{40}(p, n){\mathrm{K}}^{40}$ and the corresponding $Q\text{'}\mathrm{s}$ were computed. Second, the thresholds for production of certain gamma rays from this reaction were measured; these thresholds provided another set of values for the $Q\text{'}\mathrm{s}$. When these $Q$ values were combined with our measurements of the gamma-ray energies, we obtained a mass difference equivalent to 1.522±0.006 Mev between ${\mathrm{A}}^{40}$ and ${\mathrm{K}}^{40}$ and an energy release of 60±8 kev in the decay of ${\mathrm{K}}^{40}$ to ${\mathrm{A}}^{40}$. This appears to conflict with other information on this branch of the decay of ${\mathrm{K}}^{40}$.