Evidence of oblate-prolate shape coexistence in the strongly-deformed nucleus 119Cs

Kaikai Zheng ,J Partanen,B Cederwall,A Astier,Y.K Wang,P Ruotsalainen,J Uusitalo,Minna‐Liisa Luoma ,R D Page ,Z.H Zhang,M Sandzelius,D T Joss ,S Guo,C Andreoiu,H Tann,Ö Aktaş ,Bo Lyu ,P W Zhao ,C M Petrache ,S Juutinen,B M Nyakó ,T Grahn,P T Greenlees ,G Zimba,J Ojala,J Tímár ,P Rahkila,R Julin,J Pakarinen,D Sohler,I Kuti,M.L Liu,M Doncel,J Sarén,W Zhang,A Ertoprak

doi:10.1016/j.physletb.2021.136645

Abstract

Prolate-oblate shape coexistence close to the ground state in the strongly-deformed proton-rich A≈120 nuclei is reported for the first time. One of the four reported bands in 119Cs, built on a 11/2− state at 670 keV, consists of nearly degenerate signature partners, and has properties which unequivocally indicate the strongly-coupled πh11/2[505]11/2− configuration associated with oblate shape. Together with the decoupled πh11/2[541]3/2− band built on the 11/2− prolate state at 110 keV, for which a half-life of T1/2=55(5)μs has been measured, the new bands bring evidence of shape coexistence at low spin in the proton-rich strongly deformed A≈120 nuclei, a phenomenon predicted since long time, but not yet observed. Calculations using the particle-number conserving cranked shell model and two dimensional tilted axis cranking covariant density functional theory support and well reproduce the observed oblate and prolate coexisting low-energy states in 119Cs.

Highlights

Prolate-oblate shape coexistence close to the ground state in the strongly-deformed proton-rich A ≈ 120 nuclei is reported for the first time
Together with the decoupled π h11/2[541]3/2− band built on the 11/2− prolate state at 110 keV, for which a half-life of T1/2 = 55(5) μs has been measured, the new bands bring evidence of shape coexistence at low spin in the proton-rich strongly deformed A ≈ 120 nuclei, a phenomenon predicted since long time, but not yet observed
Various types of oblate bands are known: superdeformed and normal deformed rotational bands in several mass regions [7], regular dipole bands in A ≈ 130 nuclei [8], bands evolving from prolate to oblate shape in neutron-rich Hf nuclei [9]

Summary

Introduction

Please cite the original version: Zheng, K.K., Petrache, C.M., Zhang, Z.H., Zhao, P.W., Wang, Y.K., Astier, A., Lv, B.F., Greenlees, P.T., Grahn, T., Julin, R., Juutinen, S., Luoma, M., Ojala, J., Pakarinen, J., Partanen, J., Rahkila, P., Ruotsalainen, P., Sandzelius, M., Sarén, J., .

Results

Conclusion