학술논문
Evidence for coexisting shapes in $^{98}$Zr through lifetime measurements
Document Type
Working Paper
Author
Singh, Purnima; Korten, W.; Hagen, T. W.; Görgen, A.; Grente, L.; Salsac, M. -D.; Farget, F.; Clément, E.; de France, G.; Braunroth, T.; Bruyneel, B.; Celikovic, I.; Delaune, O.; Dewald, A.; Dijon, A.; Delaroche, J. -P.; Girod, M.; Hackstein, M.; Jacquot, B.; Libert, J.; Litzinger, J.; Ljungvall, J.; Louchart, C.; Gottardo, A.; Michelagnoli, C.; Müller-Gatermann, C.; Napoli, D. R.; Otsuka, T.; Pillet, N.; Recchia, F.; Rother, W.; Sahin, E.; Siem, S.; Sulignano, B.; Togashi, T.; Tsunoda, Y.; Theisen, Ch.; Valiente-Dobon, J. J.
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Abstract
The lifetimes of first excited 2$^+$, 4$^+$ and 6$^+$ states in $^{98}$Zr were measured with the Recoil-Distance Doppler Shift method in an experiment performed at GANIL. Excited states in $^{98}$Zr were populated using the fission reaction between a 6.2 MeV/u $^{238}$U beam and a $^{9}$Be target. The $\gamma$ rays were detected with the EXOGAM array in correlation with the fission fragments identified in mass and atomic number in the VAMOS++ spectrometer. Our result shows very small B(E2;2$_1^+$ $\rightarrow$ 0$_1^+$) value in $^{98}$Zr 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 coexistence of two additional deformed shapes in this nucleus along with the spherical ground state.