Novel Variable-gain PMTs for Measuring DT and DD Fusion Neutron Hotspot Velocities on a Single Detector*

We are investigating novel microchannel plate photomultipliers (MCP-PMTs) for neutron time-of-flight (nTOF) detection systems, for which the PMT gain settings can be varied on the timescale of 10's of nanoseconds. Among the many potential applications, this offers the ability for a single detector to measure DT and/or DD neutrons, along with fusion birth gamma-rays, which may produce signal levels that differ by several orders of magnitude. Thus, both DT and DD neutron hotspot velocities could be measured with high precision on a single detector, without the need for multiple detectors which have rigorous co-timing requirements. We present measurements of the instrument responses for two prototype, variable-gain PMTs being explored for inertial-confinement-fusion (ICF) experiments at NIF, Omega, and Z.