Investigation of 152Sm by Complementary Reactions

Understanding the nuclear structure of 152Sm, along with other N = 90 isotones, has long posed a challenge. A rapid transition in shape between the spherical N = 88 150Sm and well-deformed N = 92 154Sm is observed, along with strong evidence for shape coexistence. Competing ideas have been put forward over the decades, with the most recent being that N = 90 is at the critical point of a shape phase transition. Until recently, the lack of high-precision data has not allowed the competing models to be extensively tested. In a coordinated program of investigation, a series of complementary experiments, which include high-statistics β decay, multi-step Coulomb excitation, the 150Nd(α,2n) reaction, and the (n,n'γ) reaction, have been performed for 152Sm. These experiments have revealed the existence of a pairing-isomer band, a hexadecapole band, the lack of multi-phonon β vibrational bands, and the repetition of structures built on the first excited Kπ = 0+ as built on the ground state. The status of these coordinated studies is examined.