Properties of Excited States ofP31. II. Gamma-Ray Angular Distributions and Correlations

Angular distributions and triple correlations of gamma rays emitted from several resonances in the range E/sub p/ = 1177 to 1509 kev in the Si/sup 30/(p, gamma )P/sup 31/ reaction were measured using thin, highly enriched Si/sup 30/ targets. The angular distributions and correlations lead to the resonance level assignments 1177(7/2), 1204(5/2), 1324(5/2), 1392(5/2), 1400(3/2), are in kev. The results indicate even parity for all of the resonances if it is assumed that all gamma-ray multipolarity mixings are of the form E(L + 1)/M(L). The mixing ratios are presented for most of the observed primary transitions and of several secondary transitions. The results of this study are consistent with the assignments 3.41-Mev level is identified as 7/2+ by means of angulardistribution and correlation measurements at the 1509-kev resonance. A 7/2+ assignment for the 3.41-Mev level casts doubt upon the existence of a weak transition from that level to the 1/2+ ground state. Results of several measurements designed to determine the origin of the weak gammaray peak of approximately 3.4 Mev in coincidence spectra at the 1509-kev resonance were inconclusive. Angular distributions at the 1204-kev resonance lead to the assignment of 3/2+ to the 4.26-Mev level. Limitations are placed on themore » possible assignments for the 4.43 and 5.01-Mev levels. Both members of the doublet near E/sub p/ = 1481 kev are found to decay mainly to the ground state and each have J = 3/2 on the basis of anguiar distributions. The value of GAMMA /sub p/ GAMMA /sub gamma / GAMMA / sub t/ was determined for each of the resonances. Results of this study are discussed in terms of recent collective model calculations for P/sup 31/. (auth)« less