New isomer in96Y marking the onset of deformation at N = 57

Ł. W. Iskra, B. Fornal, S. Leoni, G. Bocchi, A. Petrovici, C. Porzio, A. Blanc, G. De France, M. Jentschel, U. Köster, P. Mutti, J.-M. Régis (+24 others)
2017 Europhysics letters  
Medium and high spin structure in the 94Y isotope produced in fission induced by cold neutrons W Iskra, B Fornal, S Leoni et al. -Structure of odd -odd : experiment and theory D Pantelica, A Pantelica, F Negoita et al. -Shape coexistence in neutron-rich nuclei A Gade and S N Liddick -Recent citations New levels in spherical 96Y E. H. Wang et al -EXILL-a high-efficiency, high-resolution setup for -spectroscopy at an intense cold neutron beam facility M. Jentschel et al -Medium and high spin
more » ... and high spin structure in the 94 Y isotope produced in fission induced by cold neutrons ? W Iskra et al -This content was downloaded from IP address 207.241.231.83 on 26/PACS 23.20.Lv -γ transitions and level energies PACS 25.85.Ec -Neutron-induced fission PACS 21.60.-n -Nuclear structure models and methods Abstract -The level scheme of 96 Y was significantly extended and a new 201 ns isomer was located at 1655 keV excitation energy, with spin-parity assignment of 5 ± or 6 − . The isomer decays to spherical low-spin structure by transitions with large hindrance and is fed by a short cascade which resembles the beginning of a rotational band. This is in analogy with the feeding and decay pattern of the 4 − isomer in 98 Y, here confirmed, by lifetime analysis, as a bandhead of a rotational structure with sizable deformation. It is suggested that the new isomer in 96 Y arises from a shape change between deformed and spherical configurations, which indicates the appearance of deformation already at N = 57 in the yttrium chain. The experimental findings for 96 Y are strengthened by theoretical calculations based on the complex Excited Vampir model. The shape of a particular nucleus results from the interplay between the collective (macroscopic) and singleparticle (microscopic) configurations and, therefore, it strongly depends on both the atomic number Z and the neutron number N . The neutron-rich nuclei around Z = 40 and N = 60 provide one of the best territories for the exploration of this sensitivity. Indeed, the sudden onset of the deformation observed for neutron-rich 12001-p1 12001-p6
doi:10.1209/0295-5075/117/12001 fatcat:ajplldj5sffk5kanhy5vwjqyqi