%0 Journal Article
%T Pseudospin Symmetry and Microscopic Origin of Shape Coexistence in the Ni-78 Region: A Hint from Lifetime Measurements
%A Delafosse, C. et al
%A Gadea, A.
%A Perez-Vidal, R. M.
%A Domingo-Pardo, C.
%J Physical Review Letters
%D 2018
%V 121
%N 19
%I Amer Physical Soc
%@ 0031-9007
%G English
%F Delafosse_etal2018
%O WOS:000449791600008
%O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=3800), last updated on Tue, 27 Nov 2018 13:32:59 +0000
%X Lifetime measurements of excited states of the light N = 52 isotones Kr-88, Se-86, and Ge-84 have been performed, using the recoil distance Doppler shift method and VAMOS and AGATA spectrometers for particle identification and gamma spectroscopy, respectively. The reduced electric quadrupole transition probabilities B(E2; 2(+)-> 0(+)) and B(E2; 4(+)-> 2(+)) were obtained for the first time for the hard-to-reach 84Ge. While the B(E2; 2(+)-> 0(+) ) values of Kr-88, Se-86 saturate the maximum quadrupole collectivity offered by the natural valence (3s, 2d, 1g(7/2), 1h(11/2)) space of an inert Ni-78 core, the value obtained for Ge-84 largely exceeds it, suggesting that shape coexistence phenomena, previously reported at N less than or similar to 49, extend beyond N = 50. The onset of collectivity at Z = 32 is understood as due to a pseudo-SU(3) organization of the proton single-particle sequence reflecting a clear manifestation of pseudospin symmetry. It is realized that the latter provides actually reliable guidance for understanding the observed proton and neutron single particle structure in the whole medium-mass region, from Ni to Sn, pointing towards the important role of the isovector-vector rho field in shell-structure evolution.
%R 10.1103/PhysRevLett.121.192502
%U https://doi.org/10.1103/PhysRevLett.121.192502
%P 192502-7pp