Measurement of excited states in (40)Si and evidence for weakening of the N=28 shell gap

Phys Rev Lett. 2006 Sep 15;97(11):112501. doi: 10.1103/PhysRevLett.97.112501. Epub 2006 Sep 13.

Abstract

Excited states in (40)Si 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.