p−sdShell Gap Reduction in Neutron-Rich Systems and Cross-Shell Excitations inO20

M. Wiedeking, S. L. Tabor, J. Pavan, A. Volya, A. L. Aguilar, I. J. Calderin, D. B. Campbell, W. T. Cluff, E. Diffenderfer, J. Fridmann, C. R. Hoffman, K. W. Kemper (+6 others)
2005 Physical Review Letters  
Excited states in ^20O were populated in the reaction ^10Be(^14C,α) at Florida State University. Charged particles were detected with a particle telescope consisting of 4 annularly segmented Si surface barrier detectors and γ radiation was detected with the FSU γ detector array. Five new states were observed below 6 MeV from the α-γ and α-γ-γ coincidence data. Shell model calculations suggest that most of the newly observed states are core-excited 1p-1h excitations across the N = Z = 8 shell
more » ... . Comparisons between experimental data and calculations for the neutron-rich O and F isotopes imply a steady reduction of the p-sd shell gap as neutrons are added.
doi:10.1103/physrevlett.94.132501 pmid:15903988 fatcat:vjn4uzl7jvb63gkgh24vrqhr4q