Measurement of excited states in 40Si and evidence for weakening of the   N=28 shell gap
  Excited states in 40Si have been established by detecting gamma-rays coincident with inelastic scattering and nucleon removal reactions on a liquid hydrogen target. The low excitation energy, 986(5) keV, of the 2+[1] state provides evidence of a weakening in the N=28 shell closure in a neutron-rich nucleus devoid of deformation-driving proton collectivity. 
C.M. Campbell, N. Aoi, D. Bazin, M.D. Bowen, B.A. Brown, J.M. Cook,   D.-C. Dinca, A. Gade, T. Glasmacher, M. Horoi, S. Kann...