Measurements of Gamma Rays for Nuclear Physics Applications at the OMEGA Laser Facility

Inertial confinement fusion (ICF) provides an opportunity to study nuclear physics at thermonuclear conditions. The main diagnostics for measuring nuclear processes in ICF experiments are neutrons and gamma rays. Gamma-ray diagnostics provide fast measurements of the nuclear reaction rate of the fusion fuel, as neutron well as scattering from (n,n’) and (n,γ) reactions. Gas Cherenkov detectors are the main gamma-ray diagnostic at the OMEGA laser facility with three separate detectors available. These detectors can be independently thresholded which enables rough spectral resolution and low-background measurements. Recently these diagnostics have been used to measure high energy gamma rays from neutron scattering on high-Z materials. This capability has also been used to design a new experiment campaign, leveraging the OMEGA-laser facility’s unique capability to measure the D(T,γ)⁵He branching ratio as a function of the thermal ion temperature, and the D(D,γ)⁴He branching ratio. These measurements will provide high-fidelity nuclear data at conditions that have not been probed at accelerator facilities, providing valuable data and insight to the nuclear structure of the ⁵He and ⁴He nuclei.