Examining the fragmentation of 158 A GeV lead ions on copper target: Charge-changing cross sections

A stack of plastic CR-39 Track Detectors were exposed to 158 A GeV 207Pb ions at the CERN-SPS beam facility. The exposure of stack was performed at normal incidence with a fluence of about 1500ions/cm2. The total number of lead ions in each spill was about 7.8×1047.8×104 with eight spills on each stack. For the stack with the Cu target, the lengths of etched cones on one face of the CR-39 detectors (before and after the target) were measured. Using these measurements and charge identification methodology in CR-39 track detectors, total and partial charge changing cross sections of 158 A GeV Pb82+Pb82+ ions on Cu and CR-39 targets are determined in the charge region 63⩽Z⩽8263⩽Z⩽82. The possibilities of presence and absence of odd–even effect in measured partial charge changing cross sections of 158 A GeV Pb ions for Cu and CR-39 targets are described. The charge resolution (σZ)(σZ) achieved in the present experiment is ∼0.18e∼0.18e–0.21e. The analysis of discrepancies between our experimental results and other published results for the identical reaction is also presented.