Detection of D-$^{3}$He Fusion $\gamma $-Rays using Gas Cherenkov Detectors

The high-energy $\gamma $-ray from $^{3}$He(d,$\gamma )^{5}$Li reactions has drawn the attention of the nuclear physics and fusion community as a diagnostic signature to study the $^{5}$Li nuclear structure and the D-$^{3}$He fusion reaction. In the past, the D-$^{3}$He $\gamma $-rays have been measured via accelerator-based beam-target experiments and recently in tokamak-based fusion reactors. In this work, we report the detection of D-$^{3}$He fusion $\gamma $-rays generated from inertial confinement fusion (ICF) implosions at the OMEGA laser facility. The $\gamma $-ray signal observed using Gas Cherenkov Detectors (GCD) is proportional to the independently measured 14.7-MeV fusion proton yield and provides a high-bandwidth alternative to fusion protons for D-$^{3}$He burn-history measurements. By comparing $\gamma $-rays from D-$^{3}$He and D-T implosions, we were able to examine (1) similarities in the $\gamma $-ray spectra of D-$^{3}$He and D-T and (2) disparities in the $\gamma $-to-particle branching ratios of D-$^{3}$He and D-T. This experimental work motivates further theoretical investigation of the multichannel $^{5}$Li- and $^{5}$He-system.