The mean free path of relativistic fragments from heavy ion reactions by 1.8 A GeV 40Ar in low sensitive nuclear emulsions

Preliminary data is given for the mean free path of projectilelike fragments, 2<Z<18, emitted in 40Ar induced heavy ion reactions in nuclear emulsions at 1.8A GeV as well as in later generations of fragmentation chains. Only within a distance of one cm or less from the interaction point do we observe an enhanced collision frequency. If this observation is a signal of an anomalous fragmentation component this must have a very short mean free path or a lifetime less than 10-11s. Some suggestions are given for systematic or statistaical effects which could also possibly explain our results. (authors)