Abstract
Excited levels in 90Sr, 92Sr, 94Sr and 96Sr nuclei were reinvestigated using high-statistics multipleγ coincidence data from neutron-induced fission of 235U and spontaneous fission of 252Cf, measured using EXILL and Gammasphere arrays, respectively. The experimental goal was the search for
new excited levels and firm spin-parity assignments to known levels. Total of 23 new levels with 30 new or corrected decays and 39 new or improved spin-parity assignments were obtained in the four nuclei. Negative-parity structures on top of 3− excitation were firmly identified and extended to higher spins. New positive-parity structures in 94Sr and 96Sr were observed with 3+ excitations characteristic of γ collectivity. The 277.7-keV, E2 decay from the 1507.0-keV level to the second 0 + level in 96Sr, found in this work, completes the coexisting deformed band in this nucleus. To learn about the microscopic structure of levels in the 88−96Sr nuclei we performed Large-Scale, ShellModel (LSSM) calculations. The calculations compared to the experiment, helped the discussion of the evolution of collectivity in strontium isotopes, highlighting the important role of various single particle excitations in phase transitions and shape coexistence in the region. Special role of the neutron 9/2+[404] extruder as a catalyst of the deformation change in the region is highlighted.
new excited levels and firm spin-parity assignments to known levels. Total of 23 new levels with 30 new or corrected decays and 39 new or improved spin-parity assignments were obtained in the four nuclei. Negative-parity structures on top of 3− excitation were firmly identified and extended to higher spins. New positive-parity structures in 94Sr and 96Sr were observed with 3+ excitations characteristic of γ collectivity. The 277.7-keV, E2 decay from the 1507.0-keV level to the second 0 + level in 96Sr, found in this work, completes the coexisting deformed band in this nucleus. To learn about the microscopic structure of levels in the 88−96Sr nuclei we performed Large-Scale, ShellModel (LSSM) calculations. The calculations compared to the experiment, helped the discussion of the evolution of collectivity in strontium isotopes, highlighting the important role of various single particle excitations in phase transitions and shape coexistence in the region. Special role of the neutron 9/2+[404] extruder as a catalyst of the deformation change in the region is highlighted.
| Original language | English |
|---|---|
| Pages (from-to) | 1-27 |
| Number of pages | 27 |
| Journal | Phys.Rev. C |
| Volume | 104 |
| DOIs | |
| Publication status | Published - 13 Dec 2021 |