γ-ray spectroscopy of one-proton knockout from 45Cl

The role of proton shell effects in the structure of the N = 28 isotones Cl-45 and S-44 has been studied via one-proton knockout from Cl-45. We compare measured gamma-ray intensities, inclusive and partial knockout cross sections, and the inclusive momentum distribution of outgoing S-44 particles with shell-model and reaction-theory predictions. The strong population in this reaction of the recently identified 4(1)(+) state in S-44, identified through its subsequent gamma-ray decay energy, makes a compelling case for a J(pi) = 3/2(+) ground state in Cl-45.