Spectrally Resolved Ion Imaging From Laser Produced Plasmas Using Cr-39 Detectors

Intense laser-produced plasmas generate bright, ultrashort bursts of accelerated ions. Reducing the required laser intensity and increasing the repetition rate of the laser to generate high energy ions is important, and mesoscopic particle targets are an attractive option to address this issue. Newer experimental strategies to measure ion energies and their angular distribution are needed in studies of such systems. In this paper, we outline a method to simultaneously measure these quantities using a single CR39 film. Although CR-39 detectors are known for ion imaging or spectroscopy, combining these specially for lower ion energies and applications to low-intensity laser experiments is not common. The paradigm chosen in our study is to consider the spatial distribution of nuclear tracks on a CR-39 sheet, while simultaneously separating them by their track diameter. Our method achieves an energy resolution of about 100 keV and a spatial resolution of tens of micrometers. In addition, ion species other than protons, i.e., carbon and oxygen, can also be imaged in an energy-resolved manner.