2024

Jodidar, P. M.; Petrache, C. M.; He, X. T.; Astier, A.; Guo, S.; Lv, B. F.; Zhang, Q. Q.; Zhang, Z. H.; Zheng, K. K.; Auranen, K.; Briscoe, A. D.; Greenlees, P. T.; Grahn, T.; Illana, A.; Joukainen, H.; Julin, R.; Louko, J.; Luoma, M.; Jutila, H.; Ojala, J.; Pakarinen, J.; Plaza, A. M.; Rahkila, P.; Ruotsalainen, P.; Sarén, J.; Tolosa-Delgado, A.; Uusitalo, J.; Zimba ,G.; Kuti, I.; Krakó, A.; Andreoiu, C.; Lawrie, E. A.; Joss, D. T.; Page, R. D.; Ertoprak, A.; Cederlöf, E. A.

The very neutron-deficient strongly deformed 117Cs nucleus has been studied using the 58Ni(64Zn, 1α1p) reaction and JUROGAM 3 γ -ray detector array coupled to the MARA recoil-mass separator. Three previously known and three newly identified rotational bands were observed up to very high spin and excitation energy. All bands are firmly assigned to 117Cs based on measured mass spectra and interconnecting transitions. The ground-state spin and parity are suggested based on the systematics of low-lying states in odd-even cesium nuclei. The systematics of bandheads in cesium nuclei reveal maximum collectivity and deformation is reached for neutron numbers 64–66, corresponding to the middle of the N = 50−82 magic shell. The rotational frequencies of the first and second crossings in the different bands are similar to those observed in the corresponding bands in the neighboring 119Cs nucleus, suggesting similar deformations of the two nuclei, but enhanced softness in 117Cs. Particle number conserving cranked shell model calculations describe the observed band structures well.