Pseudospin Symmetry and Microscopic Origin of Shape Coexistence in the
Phys Rev Lett
; 121(19): 192502, 2018 Nov 09.
Article
em En
| MEDLINE
| ID: mdl-30468583
ABSTRACT
Lifetime measurements of excited states of the light N=52 isotones ^{88}Kr, ^{86}Se, and ^{84}Ge 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^{+}â0^{+}) and B(E2;4^{+}â2^{+}) were obtained for the first time for the hard-to-reach ^{84}Ge. While the B(E2;2^{+}â0^{+}) values of ^{88}Kr, ^{86}Se saturate the maximum quadrupole collectivity offered by the natural valence (3s, 2d, 1g_{7/2}, 1h_{11/2}) space of an inert ^{78}Ni core, the value obtained for ^{84}Ge largely exceeds it, suggesting that shape coexistence phenomena, previously reported at Nâ²49, 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 ρ field in shell-structure evolution.
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01-internacional
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MEDLINE
Idioma:
En
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Phys Rev Lett
Ano de publicação:
2018
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Article