Berlin 2005 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 15: Hauptvortr
äge
HK 15.4: Hauptvortrag
Montag, 7. März 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; 0gs+→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 0gs+→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)
[4] V. Chisté et al., Phys. Lett. B 514, 233 (2001)