2019 Impact factor 2.176
Hadrons and Nuclei
Eur. Phys. J. A 9, 35-47

Evolution of the N = 20 and N = 28 shell closures in neutron-rich nuclei

S. Péru - M. Girod - J.F. Berger

CEA/DIF, DPTA/SPN, Boîte Postale 12, 91680 Bruyères-le-Châtel, France

Received: 26 July 2000
Communicated by P. Schuck

Abstract
The isospin dependence of shell closure phenomena is studied for light neutron-rich nuclei within a microscopic self-consistent approach using the Gogny force. Introducing configuration mixing, 32Mg is found to be dynamically deformed, although the N=20 spherical shell closure persists at the mean-field level for all N=20 isotones. In contrast, the N = 28 spherical shell closure is found to disappear for N-Z $\geq$ 10 whereas deformed shell closures are preserved and lead to shape coexistence in 44S. Configuration mixing shows that the ground state of this nucleus is triaxially deformed. The first 2+ excitation energy Ex = 1.46 MeV and the reduced transition probability $B(E2;0^+_{\rm gs}\rightarrow 2^+_{1})$= 420 e2 fm4 obtained with our approach are in good agreement with experimental data.

PACS
21.60.Ev Collective models - 21.60.Jz Hartree-Fock and random-phase approximations - 21.10.Re Collective levels and giant resonances - 21.10.Ky Static electromagnetic moments


Copyright Società Italiana di Fisica, Springer-Verlag 2000