Coulomb excitation of 31Mg

Phys. Lett. B

700
181
(2011)
M. Seidlitz, D. Mücher, P. Reiter, V. Bildstein, A. Blazhev, N. Bree, B. Bruyneel, J. Cederkäll, E. Clement, T. Davinson, P. Van Duppen, A. Ekström, F. Finke, L.M. Fraile, K. Geibel, R. Gernhäuser, H. Hess, A. Holler, M. Huyse, O. Ivanov, J. Jolie, M. Kalkühler, T. Kotthaus, R. Krücken, R. Lutter, E. Piselli, H. Scheit, I. Stefanescu, J. Van de Walle, D. Voulot, N. Warr, F. Wenander, A. Wiens

The ground state properties of 31Mg indicate a change of nuclear shape at 
𝑁
=
19
 with a deformed 
𝐽
𝜋
=
1
/
2
+
 intruder state as a ground state, implying that 31Mg is part of the “island of inversion”. The collective properties of excited states were the 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 
5
/
2
+
 and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of 30,31,32Mg establishes that for the 
𝑁
=
19
 magnesium isotope not only the ground state but also excited states are largely dominated by a deformed pf intruder configuration.

DOI
10.1016/j.physletb.2011.05.009
Published on
nwarr