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

Nucleon knockout experiments using beryllium or carbon targets reveal a strong dependence of the quenching factors, i.e., the ratio ( R_s ) of theoretical to the experimental spectroscopic factors ( C^2S ), 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 ^1H(^17Ne, 2p ^16F) and inclusive ^12C(^17Ne,2p ^16F)X , ^12C(^17Ne, ^16F)X as well as ^1H(^17Ne,^16F)X (X-denotes undetected reaction products) reactions with ^16F in the ground and excited states were analysed. The longitudinal momentum distribution of ^16F 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 C^2S . The experimental C^2S 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, ^17Ne and ^12C .