Neutron Detection with High Bandwidth and High Dynamic Range

A neutron diagnostic for inertial confinement fusion (ICF) experiments was designed and fabricated that is suitable for both the OMEGA and National Ignition Facility (NIF) laser systems. The diagnostic measures the spectrum of fusion neutrons that are generated at peak compression. The neutrons are downshifted, or lose energy, as they escape depending on the areal density (ρr) of the imploded target. A greater number of downshifted neutrons indicates a greater ρr, a measure of the success of an ICF implosion. The neutrons are detected by transferring energy to charged particles. The neutron detector uses a foil of polyethylene as a source of protons with which neutrons can exchange energy by elastic collisions. The detector also utilizes tungsten as a shield for x-ray radiation emitted from the target. The neutron detector exhibits high bandwidth and an exceptional dynamic range of 10 which is ideal for measuring neutron spectra from implosion and ignition experiments. The detector will be tested with protons from the Multi-Terawatt laser, tested with neutrons from OMEGA, and ultimately used to diagnose NIF implosion and ignition experiments.