Radiative Decay ofd32- Hole States

Abstract

Lifetimes were measured for ${\mathrm{K}}^{39}$, ${\mathrm{Ca}}^{41}$, and ${\mathrm{Ca}}^{43}$ states formed by promoting a particle from the $d_{\frac{3}{2}}$ shell to the $f_{\frac{7}{2}}$ shell. In ${\mathrm{Ca}}^{43}$, this state occurs at 990-keV excitation and has a mean life of 0.12 ± 0.04 nsec. By taking account of the branching ratio we find that the partial mean life for the transition ${\frac{3}{2}}^{+}\to {\frac{7}{2}}^{-}$ is 45 ± 16 nsec. which represents an inhibition of 120 relative to the single-particle estimate. In ${\mathrm{Ca}}^{41}$, the hole state occurs at 2010 keV and has a lifetime of 0.8 ± 0.2 nsec. No other branch is observed, so this is the mean life for the ${\frac{3}{2}}^{+}\to {\frac{7}{2}}^{-}$ transition. It is inhibited by a factor 62 relative to the single-particle estimate. In ${\mathrm{K}}^{39}$ the state occurs at 2820 keV and the mean life for this ${\frac{7}{2}}^{-}\to {\frac{3}{2}}^{+}$ transition is less than 0.08 nsec; the inhibition here is less than 18. All of the above rates are consistent with the theoretical model of Kurath and Lawson. From additional data on ${\mathrm{Ca}}^{43}$, we find that the partial mean life for the 612-keV ${\frac{3}{2}}^{+}\to {\frac{5}{2}}^{-}$ transition is 1.4 nsec. This is 0.06 times the single-particle value and is not explainable in the scheme of Kurath and Lawson.