Peripheral fragmentation of 8B nuclei in nuclear emulsion at an energy of 1.2 GeV per nucleon

The results obtained by studying the charge topology of fragments produced in the peripheral dissociation of relativistic 8B nuclei in emulsion are presented. Fifty-five events of the peripheral dissociation of a 8B nucleus in events where there was no production of target-nucleus fragments and mesons (“white stars”) were selected. A leading contribution of the 8B → 7Be + p mode, which has the lowest energy threshold, was revealed on the basis of these events. Information about the branching ratios for dissociation modes characterized by a higher multiplicity was obtained. The dissociation of the 7Be core in 8B bears resemblance to the dissociation of a free 7Be nucleus. The transverse-momentum distributions of fragments originating from the 8B → 7Be + p dissociation mode were obtained. For these distributions, a small mean value of 〈P*T〉 = 52 ± 5 MeV/c in the c.m. frame suggests a low binding energy of the outer proton in the 8B nucleus. An indication of a strong azimuthal correlation of the fragments 7Be and p was found.