Low-lying isovector 2+ valence-shell excitations of $^{212}$Po

D. Kocheva , G. Rainovski , J. Jolie , N. Pietralla , Clement Stahl , P. Petkov , A. Blazhev , A. Hennig , A. Astier (1) , Th. Braunroth , M. L. Cortes , A. Dewald , M. Djongolov , C. Fransen , K. Gladnishki , V. Karayonchev , J. Litzinger , C. Muller-Gatermann , M. Scheck , Ph. Scholz , R. Stegmann , P. Thole , V. Werner , W. Witt , D. Wolk , P. van Isacker (2)

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

We present the results from an experiment dedicated to search for quadrupole-collective isovector valence-shell excitations, states with so-called mixed proton-neutron symmetry (MSS), of 212Po. This nucleus was studied in an α-transfer reaction. The lifetimes of two short-lived excited states, candidates for the one-phonon MSS, were determined by utilizing the Doppler shift attenuation method. The experimental results are in qualitative agreement with a simple single-j shell model calculation, which, together with the observed lack of quadrupole collectivity, indicates that the isovector nature of low-lying states is a property of the leading single-particle valence shell configuration.

Domaines: Physique [physics]; Physique Nucléaire Expérimentale [nucl-ex]

D. Kocheva, G. Rainovski, J. Jolie, N. Pietralla, Clement Stahl, et al.. Low-lying isovector 2+ valence-shell excitations of $^{212}$Po. Physical Review C, 2016, 93, pp.011303(R). ⟨10.1103/PhysRevC.93.011303⟩. ⟨in2p3-01259972⟩