Proton spectra from $^3$He+T and $^3$He+$^3$He fusion at low center-of-mass energy

Proton spectra from the $^3$He+$^3$He and T+$^3$He have been studied at the OMEGA laser facility using inertially-confined plasmas. These high-temperature plasmas are created using shock-driven `exploding pusher' implosions. The advantage of using these plasmas is that they better mimic astrophysical systems than cold-target accelerator experiments, and are suited to unique low-energy measurements. The measured proton spectra disagree substantially with R-matrix predictions made using data from the mirror T+T reaction. R-matrix fits to the spectra suggest significant uncertainty in the proton energy distribution [A.B. Zylstra et al., Phys. Rev. Lett. 119, 222701 (2017)]. This reaction is directly relevant to the solar proton-proton chain, and these low-energy spectra may aid interpretation of low-statistics cross section measurements in accelerator experiments.