Exploring the Low-Z Shore of the Island of Inversion at N=19
The technique of invariant mass spectroscopy has been used to measure, for the first time, the ground state energy of neutron-unbound (28)F, determined to be a resonance in the (27)F + n continuum at 220(50) keV. States in (28)F were populated by the reactions of a 62 MeV/u (29)Ne beam impinging on a 288 mg/cm(2) beryllium target. The measured (28)F ground state energy is in good agreement with USDA/USDB shell model predictions, indicating that pf shell intruder configurations play only a small role in the ground state structure of (28)F and establishing a low-Z boundary of the island of inversion for N = 19 isotones.
Christian, G., N. Frank, S. Ash, T. Baumann, D. Bazin, J. Brown, Paul A. DeYoung, J. E. Finck, A. Gade, G. F. Grinyer, A. Grovom, J. D. Hinnefeld, Eric M. Lunderberg, B. Luther, M. Mosby, S. Mosby, Tim Nagi, Graham F. Peaslee, W. F. Rogers, J. K. Smith, J. Snyder, A. Spyrou, M. J. Strongman, M. Thoenessen, M. Warren, D. Weisshaar and A. Wersal. "Exploring the Low-Z Shore of the Island of Inversion at N=19." Physical Review Letters 108, no. 3.00 (2012).