One-neutron knockout reaction of 17C on a hydrogen target at 70 MeVucleon

摘要

First experimental evidence of the population of the first2?state in16C above the neutron threshold is obtained by neutron knockout from17C on a hydrogen target. The invariant mass method combined with in-beamγ-ray detection is used to locate the state at 5.45(1) MeV. Comparison of its populating cross section and parallel momentum distribution with a Glauber model calculation utilizing the shell-model spectroscopic factor confirms the core-neutron removal nature of this state. Additionally, a previously known unbound state at 6.11 MeV and a new state at 6.28(2) MeV are observed. The position of the first2?state, which belongs to a member of the lowest-lyingp–sdcross shell transition, is reasonably well described by the shell-model calculation using the WBT interaction.