Peripheral fragmentation of the $^8$B nuclei at an energy of 1.2A GeV in nuclear track emulsion

The results of investigations dealing with the charge topology of the fragments produced in peripheral dissociation of relativistic 8 B nuclei in emulsion are presented. 55 events of peripheral dissociation of the 8 B nucleus were selected from the events which do not involve the production of the target-nucleus fragments and mesons (“white” stars). A leading contribution of the 8 B → 7 Be+p mode having the lowest energy threshold was revealed on the basis of those events. Information on the relative probability of dissociation modes with a larger multiplicity was obtained. The dissociation of a 7 Be core in 8 B indicates an analogy with that of the free 7 Be nucleus. The transverse momentum distributions of the fragments from the 8 B → 7 Be+p dissociation mode were obtained. Their small average value, < P t > = 52 MeV/c, in the c.m.s. suggests a low binding energy of the external proton in the 8 B nucleus. An indication for a strong azimuthal correlation of the 7 Be and p fragments was got.