In-beam γ-ray spectroscopy and inclusive two-proton knockout cross section measurements at N ≈ 40

Abstract

In-beam γ-ray spectroscopy of Fe66,68 following intermediate-energy one- and two-proton knockout from cobalt and nickel secondary beams has been performed at the National Superconducting Cyclotron Laboratory. New transitions have been observed in Fe66 and Fe68. This is the first observation of γ-ray transitions in Fe68. In addition, Cr64 was produced using the Be9(Fe66,Cr64)X two-proton knockout reaction. An unexpectedly low inclusive cross section is observed for this reaction, an order of magnitude smaller than for the Be9(Ni68,Fe66)X reaction. This observation is discussed in terms of a significant structural difference between Fe66 and Cr64 and considerable admixtures of ν(pf)n-2(g9/2)+2 configurations in the ground and excited states of Cr64 at N=40. © 2008 The American Physical Society.