Fragmentation of Very High Energy Heavy Ions

We present experimental results on fragmentation charge-changing cross sections of 158 A GeV lead ions (charge Z = 82e) incident on Cu and CR39 targets. To detect and identify the relativistic ions, the nuclear track detector CR39 was used. When an ion crosses a nuclear track detector foil, it produces damages at the level of molecular bonds, forming the so called “latent track”. During the chemical etching of the detector in a basic water solution, etch-pit cones are formed on both sides of the foil. The base area and the height of each cone are functions of the Restricted Energy Loss (REL) of the incident ion and thus of its charge Z .