Investigation of charge yields, charge correlations, and multifragmentation of Au-197 and Pb-208 projectiles at beam energies between 1.0-GeV/nucleon and 158-GeV/nucleon

We have studied fragmentation processes of ${}^{208}\mathrm{Pb}$ projectiles at 1.0 and 158 GeV/nucleon and of ${}^{197}\mathrm{Au}$ projectiles at 10.6 GeV/nucleon in collisions with targets ranging from ${\mathrm{CH}}_{2}$ to Pb. This is the first time projectile fragmentation has been investigated in such a large projectile energy range with the same experimental technique and with high statistical significance. For our experiments we used stacks of thin CR-39 and BP-1 nuclear track detectors. This experimental method allows measurement of the trajectories and charges of all particles with charge numbers $Zg~6$ or $Zg~7$ depending on the detection threshold. Yield spectra for the fragment charge Z and the charge sum of the detected fragments show significant target and energy dependences, which originate from different excitation energy spectra of the projectile residues in collision with light target nuclei, especially for the hydrogen target, and additionally from contributions by electromagnetic dissociation in collisions with heavy target nuclei at high beam energies. The characteristics of the breakup of the prefragment in a multifragmentation reaction were investigated based on charge correlations. No significant target dependence was observed for the different energies. This shows that the memory in the special entrance channel of the reaction is lost before the excited prefragment breaks up into smaller particles.