Evidence for Coexisting Shapes through Lifetime Measurements in $^{98}$Zr

Purnima Singh (1) , W. Korten (1) , T.W. Hagen , A. Görgen , L. Grente (1) , M.-D. Salsac (1) , F. Farget (2) , E. Clément (2) , G. de France (2) , T. Braunroth , B. Bruyneel (1) , I. Celikovic (2) , O. Delaune (2) , A. Dewald , A. Dijon (2) , J.-P. Delaroche (3) , M. Girod (3) , M. Hackstein , B. Jacquot (2) , J. Libert (3) , J. Litzinger , J. Ljungvall (4) , C. Louchart (1) , A. Gottardo , C. Michelagnoli , C. Müller-Gatermann , D.R. Napoli , T. Otsuka , N. Pillet (3) , F. Recchia , W. Rother , E. Sahin , S. Siem , B. Sulignano (1) , T. Togashi , Y. Tsunoda , Ch. Theisen (1) , J.J. Valiente-Dobon

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
2 GANIL - Grand Accélérateur National d'Ions Lourds
3 DAM - Direction des Applications Militaires
4 CSNSM - Centre de Sciences Nucléaires et de Sciences de la Matière

The lifetimes of the first excited 2+, 4+, and 6+ states in Zr98 were measured with the recoil-distance Doppler shift method in an experiment performed at GANIL. Excited states in Zr98 were populated using the fission reaction between a 6.2  MeV/u U238 beam and a Be9 target. The γ rays were detected with the EXOGAM array in correlation with the fission fragments identified by mass and atomic number in the VAMOS++ spectrometer. Our result shows a very small B(E2;21+→01+) value in Zr98, thereby confirming the very sudden onset of collectivity at N=60. The experimental results are compared to large-scale Monte Carlo shell model and beyond-mean-field calculations. The present results indicate the coexistence of two additional deformed shapes in this nucleus along with the spherical ground state.

Mots clés: Nuclear Physics

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

Purnima Singh, W. Korten, T.W. Hagen, A. Görgen, L. Grente, et al.. Evidence for Coexisting Shapes through Lifetime Measurements in $^{98}$Zr. Physical Review Letters, 2018, 121 (19), pp.192501. ⟨10.1103/PhysRevLett.121.192501⟩. ⟨hal-01922074⟩