Coulomb excitation of 29,30Na: Mapping the borders of the island of inversion

Nuclear shell evolution in neutron-rich Na nuclei around 𝑁=20 was studied by determining reduced transition probabilities, i.e., 𝐵⁡(𝐸⁢2) and 𝐵⁡(𝑀⁢1) values, in order to map the border of the island of inversion. To this end Coulomb-excitation experiments, employing radioactive 29,30Na beams with a final beam energy of 2.85 Me⁢V/nucleon, were performed at REX-ISOLDE, CERN. De-excitation 𝛾 rays were detected by the MINIBALL 𝛾-ray spectrometer in coincidence with scattered particles in a segmented Si detector. Transition probabilities to excited states were deduced. The measured 𝐵⁡(𝐸⁢2) values agree well with shell-model predictions, supporting the idea that in the Na isotopic chain the ground-state wave function contains significant intruder admixture already at 𝑁=18, with 𝑁=19 having an almost pure two-particle–two-hole deformed ground-state configuration.

Authors: M. Seidlitz, P. Reiter, R. Altenkirch, B. Bastin, C. Bauer, A. Blazhev, N. Bree, B. Bruyneel, P. A. Butler, J. Cederkäll, T. Davinson, H. De Witte, D. D. DiJulio, J. Diriken, L. P. Gaffney, K. Geibel, G. Georgiev, R. Gernhäuser, M. Huyse, N. Kesteloot, T. Kröll, R. Krücken, R. Lutter, J. Pakarinen, F. Radeck, M. Scheck, D. Schneiders, B. Siebeck, C. Sotty, T. Steinbach, J. Taprogge, P. Van Duppen, J. Van de Walle, D. Voulot, N. Warr, F. Wenander, K. Wimmer, P. J. Woods, and K. Wrzosek-Lipska

Doi: 10.1103/PhysRevC.89.024309

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Journal: Phys. Rev. C

Page number: 024309

Published on: 2014-02-19

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