Interactions of energetic gold nuclei in nuclear emulsions

Abstract

The nuclear interactions of $_{{\mathrm{}}^{1}{\mathrm{}}_{79}^{97}}\mathrm{Au}$ nuclei of initial energy 990 MeV/nucleon have been studied in nuclear emulsions as they slow down and stop. Typically, these interactions are fragmentations of the incident nucleus into an average of 2.0\ifmmode\pm\else\textpm\fi{}0.3 fragments with Z\ensuremath{\ge}3 and 4.2\ifmmode\pm\else\textpm\fi{}0.2 helium nuclei. As many as eight Z\ensuremath{\ge}3 fragments or 22 helium nuclei have been observed to be produced in a single interaction. The dependence on incident energy and target nucleus is discussed. Some 7% of the interactions appear to be fission in flight of the excited projectile nucleus emerging from the interaction, with the release of two highly charged fragments that contain most, if not all, of the incident charge. The charge distribution of these fragments ranges from symmetric to highly asymmetric.