Abstract
The structure of P35 was studied with a one-proton knockout reaction at 88 MeV/u from a S36 projectile beam at NSCL. The γ rays from the depopulation of excited states in P35 were detected with GRETINA, while the P35 nuclei were identified event-by-event in the focal plane of the S800 spectrograph. The level scheme of P35 was deduced up to 7.5 MeV using γ−γ coincidences. The observed levels were attributed to proton removals from the sd shell and also from the deeply bound p1/2 orbital. The orbital angular momentum of each state was derived from the comparison between experimental and calculated shapes of individual (γ-gated) parallel momentum distributions. Despite the use of different reactions and their associate models, spectroscopic factors, C2S, derived from the S36(−1p) knockout reaction agree with those obtained earlier from S36(d,He3) transfer, if a reduction factor Rs, as deduced from inclusive one-nucleon removal cross sections, is applied to the knockout transitions. In addition to the expected proton-hole configurations, other states were observed with individual cross sections of the order of 0.5 mb. Based on their shifted parallel momentum distributions, their decay modes to negative parity states, their high excitation energy (around 4.7 MeV), and the fact that they were not observed in the (d,He3) reaction, we propose that they may result from a two-step mechanism or a nucleon-exchange reaction with subsequent neutron evaporation. Regardless of the mechanism, that could not yet be clarified, these states likely correspond to neutron core excitations in P35. This newly identified pathway, although weak, offers the possibility to selectively populate certain intruder configurations that are otherwise hard to produce and identify.