Nuclear reactions of relativistic 238U- and 139La-ions with light target atoms

Abstract

We report some results obtained during the study of the interaction of 960 MeV/nucleon 238 U, 460 MeV/nucleon 238 U, and 460 MeV/nucleon 139 La ions with light target atoms. CR-39 ( a polycarbonate, having a composion of C 12 , H 18 , O 7 ) was used as the target as well as the detector. Experimental values of charge changing mean free path have been obtained and compared with those computed using geometrical overlap model. Ranges of these projectiles in the CR-39 plastic have also been measured. Binary fission is found to be the most common mode of interaction. However, some higher order fission events along with events having exceptionally high multiplicity (clusters, containing more than thirty small tracks) have also been observed for 960 MeV/nucleon 238 U-ions near their Bragg peaks. The origin of these high multiplicity events could not be traced to a single isotopic source, such as the presence of a tiny speck of radioactive contamination.