Energy Levels in Ca41 and the Mass Difference between A40 and Ca40

Abstract

The reaction ${\mathrm{Ca}}^{40}\mathrm{}(d,p)\mathrm{}{\mathrm{Ca}}^{41}$ was studied and $Q$-values of 6.17, 4.22, 3.76, 2.31 Mev were found. Four additional $Q$-values 3.2, 2.9, 2.7, 2.5 Mev are probable. The mass increment (${\mathrm{A}}^{41}$ - ${\mathrm{A}}^{40}$) - (${\mathrm{Ca}}^{41}$ - ${\mathrm{Ca}}^{40}$) = 2.54±0.03 mMU was obtained by comparing the end groups of the two reactions ${\mathrm{A}}^{40}\mathrm{}(d,p)\mathrm{}{\mathrm{A}}^{41}$ and ${\mathrm{Ca}}^{40}\mathrm{}(d,p)\mathrm{}{\mathrm{Ca}}^{41}$. These data combined with data from two other nuclear reactions give the mass difference ${\mathrm{Ca}}^{40}$ - ${\mathrm{A}}^{40}$ = 0.27±0.21 mMU, indicating that ${\mathrm{A}}^{40}$ is slightly more stable than ${\mathrm{Ca}}^{40}$. This mass difference is compared with data on the radioactive decay of ${\mathrm{K}}^{40}$, showing that the assignment of the 1.55-Mev $\gamma$-ray to ${\mathrm{K}}^{40}$→${\mathrm{A}}^{40}$ $K$-capture process is reasonable.