Target fragmentation in proton-nucleus and 16O-nucleus reactions at 60 and 200 GeV/nucleon

Target remnants with Z<3 from proton-nucleus and 16O-nucleus reactions at 60 and 200 GeV/nucleon were measured in the angular range from 300 to 1600 (-1.7 < η < 1.3) employing the Plastic Ball detector. The excitation energy of the target spectator matter in central oxygen-induced collisions is found to be high enough to allow for complete disintegration of the target nucleus into fragments with Z < 3. The average longitudinal momentum transfer per proton to the target in central collisions is considerably higher in the case of 16O-induced reactions (≅ 300 MeV/c) than in proton-induced reactions (≅ 130 MeV/c). The baryon rapidity distributions are roughly in agreement with one-fluid hydrodynamical calculations at 60 GeV/nucleon 16O+Au but are in disagreement at 200 GeV/nucleon, indicating the higher degree of transparency at the higher bombarding energy. Both, the transverse momenta of target spectators and the entropy produced in the target fragmentation region are compared to those attained in head-on collisions of two heavy nuclei at Bevalac energies. They are found to be comparable or do even exceed the values for the participant matter at beam energies of about 1-2 GeV/nucleon. (orig.)