ELECTRIC DIPOLE DECAYS OF 31-OCTUPOLE STATES

The -ray decay modes of the octupole 31- state have been determined for Ca42, Ti48, Ni60, and Zn66 from measurements of (p, p) spectra using a coincidence-anticoincidence Ge(Li)-NaI(Tl) spectrometer. Available information for Ti46, Ni62, Ge70, and Ge72 is also summarized. A large variation in the ratio of reduced E1 transition probabilities, R=B(E1:31-22+)B(E1:31-21+), has been observed. The experimental value R-0.5 for Ti48 is much lower than the shell-model estimate (R=) due to Soga, which assumed a pure (f72)8 configuration and characterized the 21+, 22+, and 31- states according to their isospin properties. This result seems to require a substantial isovector component in the 31- states of Ti48. Comparisons are also made with Leper's estimate for the B(E1:32) value based on a vibrational model, as well as with the predictions of Soga, using perturbation theory to estimate isovector components in the 21+ and 22+ states. © 1969 The American Physical Society.