Proton-Induced Deuteron Knockout ( p,pd ) on 12C and 16O at 226 MeV

Abstract The proton-induced deuteron knockout reaction $(p,pd)$ provides a unique opportunity to exploit proton–neutron correlations and the deuteron cluster structure of nuclei. Direct deuteron knockout experiments on $^{12}$C and $^{16}$O under quasi-free scattering conditions have been carried out under the ONOKORO project using a 226-MeV proton beam at the Research Center for Nuclear Physics, Osaka, Japan. Deuterons from the knockout reaction, acting as clusters, were unambiguously detected at the focal plane of the Large Acceptance Spectrometer. Outgoing protons, following the knockout of clusters, were detected at the focal plane of the Grand Raiden spectrometer to correctly reconstruct the expected events. $(p,pd)$ reactions are established successfully, and excitation energy spectra for the residual nuclei $^{10}$B and $^{14}$N are obtained. Results showed that a large difference in transition strength toward the low-lying energy level of residual nuclei, including the ground state, was found in comparison to other studies. Theoretical calculations using the Proton-Induced KnockOut reaction calculation for Exclusive processes (PIKOE) package based on the distorted-wave impulse approximation are conducted to deduce the triple differential cross section of the $(p,pd)$ reaction, and experimental spectroscopic factors of the deuteron cluster are obtained by normalizing the experimental cross section to the theoretical computation. Consistent spectroscopic factors in comparison to shell-model expectations are obtained for transitions involving the orbital angular momentum $L=0$ of the cluster. The present work demonstrates that the $(p,pd)$ reactions at 226 MeV as a spectroscopic tool have an advantage in examining spectroscopic aspects of deuteron clustering and the mechanism to form a proton–neutron pair in the spin triplet state with negligible interference of final-state interactions and refraction effects.