ULTRA HEAVY-ION STUDIES WITH PLASTIC NUCLEAR TRACK DETECTORS - APPLICATION TO COSMIC-RAYS

In order to investigate plastic track detectors similar to those used in the UHCRE, our group has participated in several accelerator experiments in the past few years. The goal of these experiments was to determine the detector response to ultra heavy ions and to study the parameters which could affect this response. We have found that a corrected Bethe-Bloch formula should be used to obtain the ultra heavy ion energy losses and ranges in plastic detectors. The intrinsic charge uncertainty for polycarbonate associated to the experimental method used is sigma-z = (1.05 +/- 0.16) charge units for Z > 60 ions. By reproducing the UHCRE exposure and storage conditions a charge uncertainty of sigma-z = (1.70 +/- 0.19) charge units is obtained. This charge uncertainty still allows the separation of the Lead and Platinum charge groups of cosmic radiation.