NIF neutron bang time detector prototype test on OMEGA

The time interval between the beginning of the laser pulse and the peak of neutron emission (bang time) is an important characteristic of inertial confinement fusion (ICF) implosions, directly comparable to numerical simulation. For this reason, neutron bang time (NBT) detectors have been successfully operated on ICF facilities such as the Nova and OMEGA lasers, and have been proposed as a core diagnostic for the National Ignition Facility (NIF). Prototypes of the NBT detector suitable for the NIF have been built and tested on the 60-beam OMEGA laser system. These prototypes have three channels. The first, most-sensitive channel consists of a fast plastic scintillator coupled with a microchannel-plate (MCP) photomultiplier tube (PMT). The second and third channels are based on a synthetic polycrystalline diamond produced by chemical vapor deposition (CVD). These three independent channels will be able to cover a wide range of DD and DT neutron yields: from 1×10⁹ to 1×10¹⁶. The signals from the NBT prototype channels are recorded on a fast digital oscilloscope. Absolute timing was accomplished using the OMEGA optical fiducial system. The NIF NBT prototypes show better than 100-ps timing accuracy, satisfying the NIF specification.