Nuclear transparency in large momentum transfer quasielastic scattering

We measured simultaneously pp elastic and quasielastic (p,2p) scattering in hydrogen, deuterium, and carbon for momentum transfers of 4.8 to 6.2 (GeV/ c)(2) at incoming momenta of 5.9 and 7.5 GeV/c and center-of-mass scatterin g angles in the range theta(c.m.) = 83.7 degrees-90 degrees. The nuclear tr ansparency is defined as the ratio of the quasielastic cross section to the free pp cross section. At incoming momentum of 5.9 GeV/c, the transparency of carbon decreases by a factor of 2 from theta(c.m.) = 85 degrees to thet a(c.m.) similar or equal to 89 degrees. At the largest angle the transparen cy of carbon increases from 5.9 to 7.5 GeV/c by more than 50%. The transpar ency in deuterium does not depend on incoming momentum nor an theta(c.m.). [S0031-9007(98)07818-1].