Fragmentation cross sections ofSi28at 14.5 GeV/nucleon

We used CR39 plastic nuclear track detectors (${\mathrm{C}}_{12}$ ${\mathrm{H}}_{18}$ ${\mathrm{O}}_7$) in combination with automatic track measurement techniques to determine total charge changing and partial cross sections for the production of fragments of charge $Z_F$=6 to $Z_F$=13 in collisions of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ beam nuclei at 14.5 GeV/nucleon in targets H, C, CR39, (${\mathrm{C}}_{18}$ ${\mathrm{H}}_{38}$O), Al, Cu, Ag, and Pb. By application of factorization rules, measured partial cross sections are separated into pure nuclear and electromagnetic components. The cross sections for electromagnetic dissociation agree with theoretical models. The results are consistent with a $Z^2$ dependence of virtual photon spectra.