Investigation of ~(152)Smb m by Complementary Reactions

摘要

Understanding the nuclear structure of ~(152)Sm,along with otherN =90 isotones, haslong posed a challenge. A rapid transition in shape between the spherical N = 88 ~(150)Smand well-deformed N = 92 ~(154)Smis observed, along with strong evidence for shape coexistence. Competingideas have been put forward over the decades, with the most recent being that N = 90 is at thecritical point of a shape phase transition. Until recently, the lack of high-precision data has notallowed the competing models to be extensively tested. In a coordinated program of investigation,a series of complementary experiments, which include high-statistics ~Bdecay, multi-step Coulombexcitation, the ~150Nd(a, 2n) reaction, and the(n,n'y)have been performed for ~152Sm.These experiments have revealed the existence of a pairing-isomer band, a hexadecapole band, thelack of multi-phonon B vibrational bands, and the repetition of structures built on the first excited = 0+ as built on the ground state. The status of these coordinated studies is examined.