Electromagnetic properties of 39K bound states

Abstract

The 39K energy levels located at 2.53, 2.82, 3.02, 3.60, 3.88 and 3.94 MeV have been studied in the 42Ca (p, α) 39K and 39K (p, p′) 39K reactions using an angular correlation technique to gain information on the spins and mixing ratios of the de-excitation radiation. The 2.53 MeV level shows an isotropic distribution in agreement with its assignment of Jπ = 1 2 + . The 2.82 MeV level has Jπ = 7 2 − , mixing ratio δ(2.82 → 0) = −0.19±0.10, an E3/M2 mixture. The 3.02 MeV level has Jπ = 3 2 − , δ(3.02 → 0) = −0.03 ± 0.15, an M2/E1 mixture. The 3.60 MeV level has Jπ = 9 2 − or 7 2 − ; it decays to the 2.82 MeV level (39%) and to the ground state (61%); the magnitude of δ(3.60 → 2.82) is large for both possible spin values; |δ(3.60 → 0)| < 0.36 if J = 9 2 and −0.36 < | δ(3.60 → 0)| < −0.14 if J = 7 2 . The 3.88 MeV level decays to the ground state; J = 1 2 is excluded, and the values J = 3 2 , 5 2 are suggested. The decay schemes of the levels at 3.94, 4.08, 4.09, 4.12, 4.47, 4.51, 4.68 and 4.74 MeV are investigated. Spin values are suggested for some of these levels by combining the present results with previously reported results obtained in direct reaction studies. The results obtained are discussed, and a weak coupling model calculation is used to estimate the 2.82 MeV ground state transition mixing ratio.