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Is seniority a partial dynamic symmetry in the first νg9/2 shell?

Is seniority a partial dynamic symmetry in the first νg9/2 shell?

Authors :
Morales, A.I.
Benzoni, G.
Watanabe, H.
de Angelis, G.
Nishimura, S.
Coraggio, L.
Gargano, A.
Itaco, N.
Otsuka, T.
Tsunoda, Y.
Van Isacker, P.
Browne, F.
Daido, R.
Doornenbal, P.
Fang, Y.
Lorusso, G.
Patel, Z.
Rice, S.
Sinclair, L.
Söderström, P.-A.
Source :
Physics Letters B. Jun2018, Vol. 781, p706-712. 7p.
Publication Year :
2018

Abstract

The low-lying structures of the midshell ν g 9 / 2 Ni isotopes 72 Ni and 74 Ni have been investigated at the RIBF facility in RIKEN within the EURICA collaboration. Previously unobserved low-lying states were accessed for the first time following β decay of the mother nuclei 72 Co and 74 Co. As a result, we provide a complete picture in terms of the seniority scheme up to the first ( 8 + ) levels for both nuclei. The experimental results are compared to shell-model calculations in order to define to what extent the seniority quantum number is preserved in the first neutron g 9 / 2 shell. We find that the disappearance of the seniority isomerism in the ( 8 1 + ) states can be explained by a lowering of the seniority-four ( 6 + ) levels as predicted years ago. For 74 Ni, the internal de-excitation pattern of the newly observed ( 6 2 + ) state supports a restoration of the normal seniority ordering up to spin J = 4 . This property, unexplained by the shell-model calculations, is in agreement with a dominance of the single-particle spherical regime near 78 Ni. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
03702693
Volume :
781
Database :
Academic Search Index
Journal :
Physics Letters B
Publication Type :
Academic Journal
Accession number :
130223949
Full Text :
https://doi.org/10.1016/j.physletb.2018.04.049