Using Gamma Rays to Measure Reaction-in-flight Interactions*

In inertial confinement fusion, the high DT fusion neutron flux creates up-scattered deuterons and tritons with MeV energies, some of which undergo DT fusion for a second time. These reaction-in-flight (RIF) interactions are valuable because they probe the stopping power of the plasma, an interesting metric for the effect of mix and its resulting increase on the electron density. RIF reactions have historically been measured through up-scattered (>15 MeV) neutrons through activation techniques and neutron time of flight detectors. I'll present an alternative technique to potentially measure the RIF interaction - the DT fusion gamma ray pathway. The promise of the RIF gamma ray pathway may allow a time resolved measurement, a metric of how the electron density in the burning hot spot evolves over time. New nuclear physics calculations were developed to calculate the MeV DT fusion gamma ray pathway and a diagnostic requirement needed to make such a measurement defined.