FRAGMENTATION OF THE PB PROJECTILE AT 158 GEV NUCLEON IN PB-PB INTERACTIONS/

We have investigated the process of fragmentation of the Pb nucleus at 158 GeV/nucleon in Pb-Pb interactions recorded in lead-emulsion chamb ers of the EMU13 CERN experiment. The number of Pb-Pb interactions fou nd was larger than that expected from the nuclear charge changing cros s section which indicates an important role of electromagnetic dissoci ation processes in Pb-Pb interactions at this high energy. The emissio n angles of multiply charged projectile fragments as well as of specta tor protons were measured using the semiautomated device with the CCD camera mounted on a microscope. Taking the advantage of the unconventi onal design of the emulsion chambers the charges of all multiply charg ed projectile fragments were measured. On the basis of these measureme nts, different modes of the Pb projectile break-up are discussed. The rates and properties of the fragmentation processes such as fission! m ultifragmentation and disintegration only into singly charged fragment s are presented.