Measurements of pd quasi-elastic scattering in 800 MeV pA collision, and momentum spread of pn system inside nucleus

Coincidence spectra of pd Quasi-Elastic Scatterings (QES) in 800 Mev proton-nucleus (pA) collisions have been measured. From the proton spectrum, the momentum spread of the pn system (''d'') inside the nucleus has been determined. The momentum spread of ''d'' (σ sub(''d'')) obtained by pd QES are compared with the spread obtained by the projectile fragmentation. It is shown that the σ sub(''d'') is much smaller at large momentum transfer region than the spread at small momentum transfer region. From a mass dependence of the ratio of the pd to pp QES cross sections, the mean free path of deuteron has been determined to be 1.7 +- 0.3 fm. The absolute value of the pd QES cross section has been reproduced by the model which is based on plane-wave impulse approximation plus attenuation due to the rescattering of the particles. The mass dependence of the cross sections was also well fitted by the model. (author)