Diverse mechanisms in proton knockout reactions from the Borromean nucleus ^{17}text {Ne}

Abstract

Nucleon knockout experiments using beryllium or carbon targets reveal a strong dependence of the quenching factors, i.e., the ratio (hbox {R}_{textrm{s}}) of theoretical to the experimental spectroscopic factors (hbox {C}^2{textrm{S}}), on the proton-neutron asymmetry in the nucleus under study. However, this dependence is greatly reduced when a hydrogen target is used. To understand this phenomenon, exclusive ^{1}text {H}(^{17}text {Ne},2hbox {p}~^{16}text {F}) and inclusive ^{12}text {C}(^{17}text {Ne},2hbox {p}~^{16}text {F})hbox {X}, ^{12}text {C}(^{17}text {Ne},^{16}text {F})hbox {X} as well as ^{1}text {H}(^{17}text {Ne},^{16}text {F})hbox {X} (X-denotes undetected reaction products) reactions with ^{16}text {F} in the ground and excited states were analysed. The longitudinal momentum distribution of ^{16}{textrm{F}} and the correlations between the detached protons were studied. In the case of the carbon target, there is a significant deviation from the predictions of the eikonal model. The eikonal approximation was used to extract spectroscopic factor values hbox {C}^2{textrm{S}}. The experimental hbox {C}^2hbox {S} value obtained with C target is markedly lower than that for H target. This is interpreted as rescattering due to simultaneous nucleon knockout from both reaction partners, ^{17}text {Ne} and ^{12}text {C}.