Properties of the levels in 22Na deduced from the 19F(α,nγ)22Na reaction

Abstract

For gamma rays following the 19F(α,nγ)22Na reaction, angular distribution, linear polarization, and DSA measurements have been analysed to extend the experimental information on the rotational bands in 22Na. In particular the spins, parities, and mean lifetimes of the following states belonging to the indicated bands have been determined; (Ex, Jπ, τm, K); 3.707 MeV, 6+, 110 ± 10 fs, K = 3+; 1.984 MeV, 3+, —, K = 0+; 4.710 MeV, 5+, 50 ± 20 fs, K = 0+; 4.071 MeV, 4+, —, K = 0+. In addition, the spins, parities and lifetimes of the 4.360, 5.063, and 5.100 MeV states were determined to be 2+, <10 fs; 2+, <20 fs; and 4+, 55 ± 15 fs respectively. Besides the known branches from the 4.710 MeV state, a 5 ± 1% branch to the 2.969 MeV state was observed; while for the 5.100 MeV state, branches of 18 ± 2, 15 ± 5, 12 ± 2, 18 ± 2, and 37 ± 3% were observed to the ground, 0.891, 1.528, 3.060, and 4.071 MeV states. All the positive parity states below 5.1 MeV have been interpreted in terms of spherical shell model configurations for six particles in the s–d shell predicted by the Manchester–Glasgow shell model program, using the Preedom and Wildenthal interaction.