Erosion of N=20 shell in Al 33 investigated through the ground-state electric quadrupole moment

K. Shimada, H. Ueno, G. Neyens, K. Asahi, D. L. Balabanski, J. M. Daugas, M. Depuydt, M. De Rydt, L. Gaudefroy, S. Grévy, Y. Hasama, Y. Ichikawa, D. Kameda, P. Morel, T. Nagatomo, L. Perrot, C. Stodel, J. C. Thomas, Y. Utsuno, W. VanderheijdenN. Vermeulen, P. Vingerhoets, E. Yagi, K. Yoshida, A. Yoshimi

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Electric quadrupole moment Q of the Al 33 ground state has been measured by means of β-NMR spectroscopy using a spin-polarized Al 33 beam produced in a projectile fragmentation reaction. The obtained Q moment, |Q exp( 33Al)|=132(16) emb, shows a significant excess from the prediction of shell model calculations within the sd shell. The result indicates sizable admixing of pf intruder configurations in the ground state, demonstrating that the N=20 shell closure certainly erodes in Al 33, a nucleus located on the border of the island of inversion. Comparison was made with predictions of the Monte Carlo shell model, and also a particle-vibration coupling model treating the neutron pairing correlations in the ground state of Al33. Again, a significant admixture of pf intruder configurations to the Al 33 ground state was needed in both theoretical approaches to explain the observed large Q.

Original languageEnglish
Pages (from-to)246-250
Number of pages5
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number2-5
Publication statusPublished - Aug 14 2012
Externally publishedYes


  • Electric quadrupole moment of Al33
  • Island of inversion
  • Quasiparticle-vibration coupling model
  • Shell model
  • β-NMR

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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