Low collectivity of the first 2$^+$ states of $^{212,210}$Po

D. Kocheva , G. Rainovski , J. Jolie , N. Pietralla , A. Blazhev , A. Astier (1) , R. Altenkirch , M. Bast , M. Beckers , S. Ansari , Th. Braunroth , M. Cappellazzo , M.L. Cortés , A. Dewald , F. Diel , M. Djongolov , C. Fransen , K. Gladnishki , A. Goldkuhle , A. Hennig , V. Karayonchev , J.M. Keatings , E. Kluge , Th. Kröll , J. Litzinger , K. Moschner , C. Müller-Gatermann , P. Petkov , M. Rudigier , M. Scheck , P. Spagnoletti , Ph. Scholz , T. Schmidt , M. Spieker , Clement Stahl , R. Stegmann , A. Stolz , A. Vogt , M. Stoyanova , P. Thöle , N. Warr , V. Werner , W. Witt , D. Wölk , J.C. Zamora , K.O. Zell , P. van Isacker (2) , V.Yu. Ponomarev

1 CSNSM - Centre de Sciences Nucléaires et de Sciences de la Matière
2 GANIL - Grand Accélérateur National d'Ions Lourds

The lifetimes of the first 2+ excited states of 212,210Po were measured in two transfer reactions 208Pb(12C,8Be)212Po and 208Pb(12C,10Be)210Po by the Recoil Distance Doppler Shift (RDDS) method and by the Doppler Shift Attenuation method (DSAM), respectively. The derived absolute B(E2) values of 2.6(3) W.u. for 212Po and 1.83(28) W.u. for 210Po indicate low collectivity. It is shown that the properties of the yrast , , and states in both nuclei cannot be described consistently in the framework of nuclear shell models. It is also demonstrated in the case of 210Po that Quasi-particle Phonon Model (QPM) calculations cannot overcome this problem thus indicating the existence of a peculiarity which is neglected in both theoretical approaches.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Physique Nucléaire Théorique [nucl-th]

D. Kocheva, G. Rainovski, J. Jolie, N. Pietralla, A. Blazhev, et al.. Low collectivity of the first 2$^+$ states of $^{212,210}$Po. 22nd International School on Nuclear Physics, Neutron Physics and Applications, Sep 2017, Varna, Bulgaria. pp.012019, ⟨10.1088/1742-6596/1023/1/012019⟩. ⟨hal-01801945⟩