The Isomeric 9/2⁺and the Lowest 7/2^-State in the Weakly Deformed N = 89 Nuclei

Abstract

The decays of the isomeric 9/2+ states which have been produced by (d, pγ) and (3He, xnγ) reactions, have been investigated in three N = 89 nuclei. The half-lives have been determined to be 5.1 ± 0.3 ns in 149Nd and 3.5 ± 0.4 μs in 153Gd. In 155Dy a 5.5 ns half-life was found, but we were unable to assign it to the 9/2+ state. The calculated E1 transition probability from the 9/2+ state has been used as a probe in suggesting the following main components for the lowest-lying 7/2- state: 7/2 5/2-[523] in 149Nd, 7/2 3/2-[521] in 153Gd and 7/2 3/2-[521] in 155Dy. The corresponding 7/2- state in 151Sm is proposed to be 7/2{1}3/2-[532] + 5/2-[523]{1}. All calculations have been performed using a particle-rotor model with a nonspheroidal Woods-Saxon potential.

Experimental study of145Cs Decay

“…Several of the N = 89 isotones were extensively studied [1][2][3][4]. In the A-~150 region, extensive systematic studies of long chains of isotones and isotopes have revealed the evolution of nuclear level structure from spherical to deformed nuclei.…”