Shell evolution approaching the N=20 island of inversion: Structure of 26Na

G. L. Wilson, W. N. Catford*, N. A. Orr, C. Aa Diget, A. Matta, G. Hackman, S. J. Williams, I. C. Celik, N. L. Achouri, H. Al Falou, R. Ashley, R. A E Austin, G. C. Ball, J. C. Blackmon, A. J. Boston, H. C. Boston, S. M. Brown, D. S. Cross, M. Djongolov, T. E. DrakeU. Hager, S. P. Fox, B. R. Fulton, N. Galinski, A. B. Garnsworthy, D. Jamieson, R. Kanungo, K. G. Leach, J. N. Orce, C. J. Pearson, M. Porter-Peden, F. Sarazin, E. C. Simpson, S. Sjue, D. Smalley, C. Sumithrarachchi, S. Triambak, C. Unsworth, R. Wadsworth

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The levels in 26Na with single particle character have been observed for the first time using the d(25Na, pγ) reaction at 5 MeV/nucleon. The measured excitation energies and the deduced spectroscopic factors are in good overall agreement with (0+1)hω shell model calculations performed in a complete spsdfp basis and incorporating a reduction in the N=20 gap. Notably, the 1p3/2 neutron configuration was found to play an enhanced role in the structure of the low-lying negative parity states in 26Na, compared to the isotone 28Al. Thus, the lowering of the 1p3/2 orbital relative to the 0f7/2 occurring in the neighbouring Z=10 and 12 nuclei - 25,27Ne and 27,29Mg - is seen also to occur at Z=11 and further strengthens the constraints on the modelling of the transition into the island of inversion.

Original languageEnglish
Pages (from-to)417-423
Number of pages7
JournalPhysics Letters B
Early online date2 Jun 2016
Publication statusPublished - 10 Aug 2016


  • 81V35
  • Na
  • Nuclear structure
  • Shell migration
  • Transfer reactions
  • γ-Ray transitions

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