Berlin 2005 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 15: Hauptvortr
äge

HK 15.4: Invited Talk

Monday, March 7, 2005, 11:45–12:15, TU MA001

Exploring the “Island of Inversion”: Coulomb excitation of ³⁰Mg and ³²Mg with MINIBALL at REX-ISOLDE — •Heiko Scheit — Max-Planck-Institut für Kernphysik, Heidelberg

Since the discovery in 1975 [1] that the neutron rich ^31,32Na isotopes are more tightly bound than expected, the unusual properties of the neutron-rich Na and Mg isotopes in this region (“island of inversion”) near the N=20 shell closure are subject of intense theoretical and experimental investigations. Nevertheless, the knowledge on these nuclei is sparse and some of the existing experimental data are not consistent, e.g. the B(E2; 0_gs⁺→2₁⁺) values for ^30,32Mg measured by different groups differ from each other by as much as a factor of two [2-4].

We therefore studied the collective properties of the neutron-rich isotopes ^30,32Mg at the energy-upgraded REX-ISOLDE facility using the MINIBALL array to detect the de-excitation γ rays after “safe” Coulomb excitation.

After a short introduction to REX and MINIBALL the present status of our knowledge of the structure of the nuclei in or near the “island of inversion” will be reviewed with special emphasis on the collectivity of the 0_gs⁺→2₁⁺ excitation in ^30,32Mg.

[1] C. Thibault et al., Phys. Pev. C 12, 644 (1975)

[2] T. Motobayashi et al., Phys. Lett. B 346, 9 (1995)

[3] B.V. Pritychenko et al., Phys. Lett. B 461, 322 (1999)