Compression phenomena and Mach shock waves in fast nucleus-nucleus collisions

Abstract

Central collisions between He, C and O projectiles in the energy range 0.2 GeV/nucleon to 4.2 GeV/nucleon and Ag and Br targets in 4 mu nuclear track detectors (AgCl crystals and nuclear emulsion) have been investigated. The measurements were directed towards effects at the target site where Mach shock phenomena were expected to be seen. Angular and energy spectra of target fragments partitioned into two groups with Z=1 and Z>or=2 have been measured up to energies of 30 MeV/nucleon. The angular distributions of the He group from events with a high number of slow secondaries show characteristic peaks varying with the projectile energy in a way consistent with the Mach shock model. The corresponding energy spectra extend to higher values in the angular region of the peaks, as expected from the model.