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HK: Fachverband Hadronen und Kerne
HK 15: Nuclear Structure and Dynamics I
HK 15.8: Talk
Monday, March 16, 2009, 18:45–19:00, H-ZO 40
Coulomb excitation at the border of the island of inversion – the case of 31Mg — •Michael Seidlitz, Peter Reiter, and Dennis Mücher — Institut für Kernphysik, Universität zu Köln
The ground state properties of 31Mg indicate a dramatic change of nuclear shape at N=19 with a highly deformed Jπ=1/2+ ground state, implying that 31Mg is part of the island of inversion [1]. The unknown collective properties of excited states were subject of a Coulomb excitation experiment at REX-ISOLDE, CERN, employing a radioactive 31Mg beam. De-excitation γ-rays were detected by the MINIBALL γ-spectrometer in coincidence with scattered particles in a segmented Si-detector. The level scheme of 31Mg was extended. Spin and parity assignment of the 945 keV state yielded a (3/2+,5/2+) value. De-excitation of this state is dominated by a strong collective M1 transition to the (3/21+) state. The deduced B(E2) and B(M1)>0.145 µN2 values are in good agreement with the properties of a rotational band built on the 1/2+ ground state [2].
[1] G. Neyens et al., Phys.Rev.Lett 94, 022501 (2005)
[2] F. Marechal et al., Phys.Rev. C 72, 044314 (2005)
Supported by the German BMBF (06KY205I).