The decays of ${}_{}{}^{39}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}$ have been studied because of the related interest in the magnitude of the axial coupling constant in nuclear matter. ${}_{}{}^{39}{}_{}{}^{}\mathrm{Ca}$ was produced in the ${}_{}{}^{39}{}_{}{}^{}\mathrm{K}\mathrm{}(p,n)\mathrm{}{}_{}{}^{39}{}_{}{}^{}\mathrm{Ca}$ reaction at $E_p=10\mathrm{}$ MeV and its half-life was measured as 860.4 ± 3.0 msec resulting in an $\mathrm{ft}$ value of 4283 ± 25 sec. The half-life of ${}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}$, formed in the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}(p,\gamma ){}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}$ reaction with 3-MeV protons on thick Ca, is 596.3 ± 1.7 msec. From the $\gamma$-ray energies of 2882.6 ± 0.3 keV and 3696.9 ± 0.5 keV measured at the 1.84- and 2.68-MeV resonances the $Q$ value of the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}(p,\gamma ){}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}$ reaction is found to be 1085.7 ± 1.4 keV. This leads to a ${}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}$ mass excess of -28 642.2 ± 1.7 keV, to a ${}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}$ decay energy of 6494.9 ± 2.0 keV, and to an $\mathrm{ft}$ value of 2849 ± 9 sec. An upper limit of 2×${10}^{-3\mathrm{}}$ is placed on the $\beta$ branching of ${}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}$ to excited states of ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$. If the free-space value of $g_A$ is used to extract the Gamow-Teller matrix element ${〈\sigma 〉}_{\exp }$ from these data we find $\frac{{〈\sigma 〉}_{\exp }}{{〈\sigma 〉}_{\mathrm{s}.\mathrm{p}.\mathrm{}}}$ values of 0.685 ± 0.009 and 0.761 ± 0.006 for ${}_{}{}^{39}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{41}{}_{}{}^{}\mathrm{Sc}$, respectively, where the ${〈\sigma 〉}_{\mathrm{s}.\mathrm{p}.\mathrm{}}$ are the relevant single-particle matrix elements.

• Received 8 May 1973

DOI:https://doi.org/10.1103/PhysRevC.8.657