ADVANCES IN SOLID-STATE NUCLEAR TRACK DETECTORS

Several types of commercially available phosphate glasses with a wide range of sensitivities have recently been developed. Chief among these is BP-1, which has a high sensitivity and an unprecedented charge resolution. CR39 has been found to respond differently at velocities below approximately 10(-2) c, where nuclear stopping begins to dominate, than at high velocities, where electronic stopping dominates. Atomic force microscopy has been shown to be a powerful new tool for the study of the etching process, using recoil tracks in mica. CR-39 has been used to set limits on cold fusion rates in strong conflict with rates claimed by some electrochemists. CR-39 and BP-1 have been used to study a number of topics in atomic and nuclear physics including charge pickup in relativistic nucleus-nucleus reactions, nuclear and electromagnetic spallation of relativistic heavy nuclei, the determination of electron attachment and stripping cross sections for relativistic heavy nuclei, and cluster radioactivity. CR-39 is being used to search for strangelets in nature and in ultrarelativistic nucleus-nucleus interactions. Several studies of cosmic ray composition, including TREK, ANTIPODE, HIIS, and UHCRE, are obtaining new results using CR-39, polycarbonate, and BP-1 glass. An experiment to search for weakly interacting massive elementary particles called WIMPs will use mica to detect very short tracks of nuclei that recoil when struck elastically by the WIMPs.