Understanding background in gas Cherenkov detectors and future detector development *

Gas Cherenkov Detectors (GCD) provide direct measurements of fusion reaction rate and other processes in inertial confinement fusion (ICF). The Cherenkov mechanism utilized in GCDs is inherently fast. However, detectors have been limited in temporal resolution by even state-of-the art photomultiplier tubes (PMT). The pulse dilation – photomultiplier tube (PD-PMT) fielded on the GCD-3 at the National Ignition Facility (NIF) provides unprecedented temporal resolution of 10 ps in gamma reaction history measurements in inertial confinement fusion experiments. First measurements of DT fusion gammas are showing slowly decaying tail feature corrupting the data quality. Detailed understanding of the cause and mitigation strategies for the tail are needed for both improving the data quality and designing future gas Cherenkov detectors for high background environments such as NIF or the Z-machine at Sandia National Laboratory.