Evolution of the N = 20 and N = 28 shell closures in neutron-rich nuclei |
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Authors: | S Péru M Girod JF Berger |
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Institution: | (1) CEA/DIF, DPTA/SPN, Boıte Postale 12, 91680 Bruyères-le-Chatel, France, FR |
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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≥ 10 whereas deformed shell closures are preserved and lead to shape coexistence in 44
S. 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+
gs→ 2+
1)= 420 e
2
fm
4 obtained with our approach are in good agreement with experimental data.
Received: 26 July 2000 / Accepted: 30 August 2000 |
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Keywords: | 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 |
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