Searching for short range correlations using (e,e'NN) reactions

Abstract

Electron induced two nucleon knockout reactions (e,e'pp) and (e,e'np) were performed for 3He, 4He and 12C nuclei with incident energies of 2.261 GeV and 4.461 GeV using the CLAS detector at Jefferson Lab. Events with missing momenta lower than the Fermi level and missing energies smaller than the pion threshold were studied. The residual system was assumed to be a spectator and the process was considered as a quasi-free knockout of an NN pair. The cross sections for 15 different reactions were presented as functions of the initial relative momentum per nucleon of the NN pair. The data showed that the initial momentum extends up to 800 MeV/c with considerable strength. The cross sections for 3He(e,e'pp)n were compared to the calculations of J.M. Laget. It was found that the final state interactions (FSI) and the meson exchange currents (MEC) dominate the cross sections and the short range properties of the NN pair were substantially undermined. However, the node of the S state wave function of the pp pair at around 400 MeV/c initial momentum starts to be recognizable in the 4.461 GeV data. The data and the theory suggest that with higher momentum transfers, especially in the region of XBj > 1, the competing processes such as FSI and MEC will be less important and the detailed study of the short-range properties of nucleons inside nuclei will be more desirable.