Study of number of black prongs in two generations of nuclear interactions in photoemulsion irradiated by 72Â GeV 22Ne

This work is a study of new aspects in relativistic nucleus-nucleus interactions using the nuclear emulsion technique and it is aimed at development of a method of search of these interactions. Layers of nuclear photographic emulsion type-BR2 with sizes 100×200mm2×600μm were irradiated with 72 GeV 22Ne beam parallel to emulsion surface. The scanning length was 110 mm. The new idea is the counting of black prongs in nuclear-nuclear interactions due to primary projectile22Ne ions and due to theirα- andZ⩾3projectile fragments, i.e. their (Z⩾2)-secondary fragments. The ratio of their black prong multiplicity distributions is measured. Black prongs are low-energy Z=1 particles in case of protons with energies below 30 MeV emitted from the residual nuclei of these high-energy interactions. Two divisions of events were used. The first one was over more peripheral events, more central and exceedingly central collisions. The second division was over collisions creating fragments Z⩾2 and without their creation. The ratios between numbers of events in such different subsets, as well the ratios between of different mean values of Nb multiplicities averaged inside these subsets were studied. These results are discussed, also in the context of other thick target experiment, studied with radiochemistry or neutron counting techniques. In addition, different versions of the mean free nuclear ranges of Ne-ions and their heavy secondary fragments have been measured and calculated. We have scheduled the further strategy of search of new phenomena in similar multiplicity distributions at greater statistics of future experiments.