Spin determinations of 31P levels from the 30Si(p, γ) reaction

Abstract

The angular distributions of primary and secondary 7-ray transitions at seven resonances in the 30Si(p,γ)31p reaction were measured with a 30 cm3 Ge(Li) detector. The strengths of the resonances between 800 and 1000 keV and the strength of the Ep = 2187 keV resonance were determined. The mean lifetime τm (or upper limits) for the 31P 5.53, 5.56 and 5.67 MeV levels was obtained from γ-ray Doppler shift measurements as <37, < 25 and 45 ±20 fs, respectively. The measurements lead to the following Jπ assignments of 3lP bound states and resonance levels:Jπ(4.63) ~+ (~+),J~(5.01) 2(½ ),J~(5.02) ,~(~ ),J=(5.53)-__- ~7 (z5+ ), J(5.56) :~ = : = 2, J(5.67) : ~, J(6.40) : 7, J(6.93) : (~, ,~), J(8.22) : ~ and Jn(8.23) : ~-. There are strong arguments which allow to identify the 5.01 and 5.67 MeV levels with the 2p3/2 and lf5/2 single-particle states, respectively. The even-parity states in 31P up to 5.8 MeV are compared with recent many-particle shell-model calculations.