Neutron Spectral Analysis for ICF

The spectrum of neutron energies emitted from an ICF implosion is one of the principal diagnostics of stagnating, burning and igniting plasmas. Unscattered neutrons contain information on the velocities of reacting ions in regions of the plasma undergoing thermonuclear burn, scattered neutrons are sensitive to the bulk properties (density, temperature, velocity, etc) of the regions in which scattering occurs and neutrons produced from secondary or tertiary processes (e.g. RIFs) are sensitive to a combination of these properties. We summarize recent progress in the modelling and analysis of the neutron energy spectra emitted from ICF implosions and highlight the different physical quantities that can, in principle, be inferred from measurements of neutron spectra emitted by both direct- and indirect-drive implosions. Some highlights include the diagnosis of propagating thermonuclear burn from the measurement of backscatter edges, analysis of the shape of the neutron energy spectrum in the 15-30 MeV range, and a methodology for inferring time-resolved quantities using nTOF detectors placed at different distances from the target. A range of analytic and deterministic computational models are used in this work, of which details will be presented.