Deformation and mixing of coexisting shapes in neutron-deficient polonium isotopes

Phys. Rev. C

92
054301
(2015)
N. Kesteloot, B. Bastin, L. P. Gaffney, K. Wrzosek-Lipska, K. Auranen, C. Bauer, M. Bender, V. Bildstein, A. Blazhev, S. Bönig, N. Bree, E. Clément, T. E. Cocolios, A. Damyanova, I. Darby, H. De Witte, D. Di Julio, J. Diriken, C. Fransen, J. E. García-Ramos, R. Gernhäuser, T. Grahn, P.-H. Heenen, H. Hess, K. Heyde, M. Huyse, J. Iwanicki, U. Jakobsson, J. Konki, T. Kröll, B. Laurent, N. Lecesne, R. Lutter, J. Pakarinen, P. Peura, E. Piselli, L. Próchniak, P. Rahkila, E. Rapisarda, P. Reiter, M. Scheck, M. Seidlitz, M. Sferrazza, B. Siebeck, M. Sjodin, H. Tornqvist, E. Traykov, J. Van De Walle, P. Van Duppen, M. Vermeulen, D. Voulot, N. Warr, F. Wenander, K. Wimmer, and M. Zielińska

Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient  
196,198,200,202
 Po 
  isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes,  
200,202
 Po 
 , the transitional and diagonal matrix elements of the 2+
1 state are determined. In  
196,198
 Po 
  multistep Coulomb excitation is observed, populating the 4+
1,0+
2, and 2+
2 states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from  
196
 Po 
  onwards. Three model descriptions are used to compare to the data. Calculations with the beyond-mean-field model, the interacting boson model, and the general Bohr Hamiltonian model show partial agreement with the experimental data. Finally, calculations with a phenomenological two-level mixing model hint at the mixing of a spherical structure with a weakly deformed rotational structure.

DOI
10.1103/PhysRevC.92.054301
Published on
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