The Scattering Interactions of Neutrons with ⁶Li and ⁷Li at Incident Neutron Energies of 14 MeV Using an Inertial Confinement Fusion Platform

Lithium isotopes are primary components of the blankets proposed for continuous, on-site fuel regeneration in DT fusion reactor facilities. The ⁶Li(n, n’)dα and ⁷Li(n, n’)tα processes are presumed the main breeding channels for the deuterium-tritium fuel. As generator of the radioactive tritium, the latter process is of crucial importance. Knowledge of the particle production cross sections and the spectra of scattered and secondary neutrons from interactions of 14-MeV neutrons (> 100 keV) in thick targets is required for simulations of neutronics and, specifically, of the tritium breeding rates. In this work, cross sections were measured of neutron-induced processes in targets of isotopically enriched lithium isotopes. The experiments used an intense source generating 10¹¹ 14-MeV neutrons in pulses of 100-ps duration. Such bright neutron flashes are generated in inertial-confinement (ICF) DT implosions¹ driven by the University of Rochester pulsed Laser System OMEGA. Secondary neutrons were measured in forward-angle geometry (θ = 0 to 7.4°) with a sensitive, neutron time-of‑flight spectrometer of high dynamic range. Total and double-differential cross sections of inelastic neutron scattering are inferred from the following reactions ⁶Li(n,n')dα and ⁷Li(n,n')tα and will be presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856.

¹ T. R. Boehly et al., Opt. Commun. 133, 495 (1997).