Abstract
Structure of the neutron-rich isotope , located northeast of a doubly-magic nucleus , is investigated by spectroscopy. Two -decay isomers in are newly found in the study of two different decays of which were produced by two reactions (i) direct in-flight fission at a primary target and (ii) decay of at an active stopper. Half-lives of the decays of the ground state, the low-spin isomer, and the high-spin isomer are determined to be 0.38(2), 0.91(5), and 0.47(4) s, respectively. Decay schemes of the decay of the high-spin isomer and of the mixed decays of the ground state and the low-spin isomer in to are constructed using the information on -ray coincidence relation and -ray intensity. Nuclear structures of the low-lying states in and are discussed by comparing the experimental results to two theoretical calculations based on a large-scale shell model and the deformed Skyrme Hartree-Fock-Bogoliubov plus deformed quasiparticle-random-phase approximation. Possible candidates for (quasi-)-band members of and states and the octupole collective state are proposed in . Increase of quadrupole, triaxial, and octupole collectivities is discussed with the increase of neutron and proton numbers.
8 More- Received 15 January 2022
- Accepted 1 April 2022
DOI:https://doi.org/10.1103/PhysRevC.105.044325
©2022 American Physical Society