Low-lying levels in 145Pm and the effective M2 transition moment

Abstract

Low-lying states in 145Pm were studied by the 145Nd(p, nγ) and 144Nd( 3He, d) reactions. We found new levels in 145Pm at 715, 751, 795, 837 and 885 KeV and possibly at 959 keV. The single-proton states 2 d 5 2 , 1 g 7 2 (61 keV) and 1 h 11 2 (795 keV) were found in low-lying states in 145Pm. The half-life of the 1 h 11 2 795 keV state was measured as 18.3±1.9 ns. The effective M2 coupling constant for the single-particle M2 transition between the 1 h 11 2 and 1 g 7 2 states is obtained as g M2 eff= (0.21±0.024) g M2 s.p.. It corresponds to the nuclear M2 susceptibility F(M2) ≈ 4. The reduction of g M2 eff is consistent with the systematics of neighboring nuclei. It was shown that the reduced matrix element 〈 11 − 2 ∥ M2∥ 7 + 2 〉 in nuclei with N ≈ 82 goes down as the neutron number goes away from the magic number N = 82, while the effective coupling constant g eff/ g remains constant. This fact indicates the uniform effect of the spin-isospin core polarization.