SHORT-RANGE INTERACTION OF NUCLEONS INSIDE THE NUCLEUS VIA HE-4(E,E'P)R REACTIONS

Cross sections for the He-4(e,e'p)R reaction have been measured for re coil momenta between 225 and 500 MeV/c. We find (1) that in the contin uum channel a peak in the missing energy spectrum appears which shifts with increasing recoil momentum in a predictable way, and (2) that fo r the highest recoil momenta (above 300 or 350 MeV/c) overall agreemen t is obtained with microscopic calculations in which the scattering on nucleon pairs predominates. These results strongly suggest that the h ighest recoil momenta are generated by the scattering on one of a pair of nucleons. This interpretation is reinforced by an observed continu um momentum distribution which, for high recoil momenta, resembles the momentum distribution of deuterium. We infer that the high momentum p art of the momentum distribution of a nucleon pair appears unmodified when embedded in a nuclear medium.