Pulse dilation system upgrade for Gamma Reaction History*

The Gamma Reaction History (GRH) diagnostic has provided a deuterium tritium (DT) fusion reaction history at the National Ignition Facility (NIF). The gammas measured from the DT fusion reaction providing crucial performance parameters for Inertial Confinement Fusion (ICF) such as fusion bang time and fusion burn width. With increased temporal resolution, the shape of the reaction history i.e., the burn profile, can be resolved. The burn profile increases our understanding of onset and truncation of thermonuclear burn as well as puts tighter limits simulations. The Pulse Dilation – Photomultiplier Tube (PD-PMT) provides 10 ps temporal resolution, enough band width for resolving the burn profile. The pulse dilation technology has been tested on the GRH sister detector NIF - Gas Cherenkov Detector (GCD). Recently one GRH gas cell was upgraded with a PD-PMT system. Lessons learned from the GCD testbed were incorporated in the design of the coupling of GRH with a PD-PMT. In this presentation an overview of the GRH upgrade project as well as characterization of GRH/PD-PMT system and burn profile data acquired from ignition class shots will be presented.