Fragmentation of (158 A GeV) Pb ions with Bi target

We have investigated the fragmentation of $^{207}$ Pb ions at 158 A GeV energy in collision with Bi target using CR39 plastic nuclear track detectors. A stack containing CR-39 detectors sandwiched with the target Bi was exposed to (158 A GeV) $^{207}$ Pb ions at SPS beam facility of CERN with a fluence of $\sim$ 1500 ions/cm$^2$. The detectors were chemically etched and scanned using optical microscope. The data in the form of etched cone height is used for the identification of charge of beam ions and the fragments produced in the charge region $63 \leq Z \leq 82$. The estimated charge-changing cross sections are significantly higher than those obtained from the geometrical model.