Search for neutron excitations across theN=20shell gap inNe25−29

Nuclear structure of the neutron rich Ne25−29 nuclei has been investigated through the in-beam γ-ray spectroscopy technique using fragmentation reactions of both stable and radioactive beams. Level schemes have been deduced for these Ne isotopes. In order to examine the importance of intruder fp configurations, they are compared to shell model calculations performed either in the restricted sd or in the larger sdpf valence space. The Ne25,26 and Ne27 nuclei were found to be in agreement with the sd shell model calculations, whereas Ne28 exhibits signatures of the intruder fp shell contribution.4 MoreReceived 27 October 2004DOI:https://doi.org/10.1103/PhysRevC.72.054316©2005 American Physical Society