Nuclear transparency in 90 c.m. quasielastic AÑp ,2 pÖ reactions

nuclear transparency deuterons were studied. Second, we review the techniques used in an earlier experiment, E834, and show that the two experiments are consistent for the carbon data. E834 also determines the nuclear transparencies for lithium, aluminum, copper, and lead nuclei as well as for carbon. A determination of the sp + , p + pd transparencies is also reported. We find for both E850 and E834 that the Asp ,2 pd nuclear transparency, unlike that for Ase , e8pd nuclear transparency, is incompatible with a constant value versus energy as predicted by Glauber calculations. The Asp ,2 pd nuclear transparency for carbon and aluminum increases by a factor of two between 5.9 and 9.5 GeV/c incident proton momentum. At its peak the Asp ,2 pd nuclear transparency is ,80% of the constant Ase , e8pd nuclear transparency. Then the nuclear transparency falls back to a value at least as small as that at 5.9 GeV/ c, and is compatible with the Glauber level again. This oscillating behavior is generally interpreted as an interplay between two components of the pN scattering amplitude; one short ranged and perturbative, and the other long ranged and strongly absorbed in the nuclear medium. A study of the A dependent nuclear transparency indicates that the effective cross section varies with incident momentum and is considerably smaller than the free pN cross section. We suggest a number of experiments for further studies of nuclear transparency effects.