Investigation of non-normal incidence charged-particle response of CR39 nuclear track detectors, with applications in nuclear diagnostics for inertial confinement fusion

Abstract

CR39 is a plastic nuclear track detector used at inertial confinement fusion (ICF) facilities to characterize the energy spectra of fusion products. This thesis presents data collected at MIT's Linear Electrostatic Ion Accelerator (LEIA) to measure CR39's detection efficiency for protons at non-normal incidence to CR39 detectors. We specifically study protons resulting from D-D fusion reactions with incident angles up to 50 degrees. Understanding the CR39 response to charged particles at an angle is essential to designing a D-D neutron spectrometer at the Z facility, which uses CR39 to detect protons incident at an angle. We find that small adjustments of 10 degrees have no effect on detection efficiency, and high detection efficiency is preserved up through 25 degrees in the range of 1.0 to 2.1 MeV. For the ICF applications, incident angles above 30 degrees are generally impractical for spectrometer design due to significant drops in proton detection. We compare the experimental results to related theoretical simulations, proposing significant constraints on these theoretical models of detection efficiency.