Ultra-fast single-crystal CVD diamonds in the particle time-of-flight (PTOF) detector for low yield burn-history measurements on the NIF

The Particle Time of Flight (PTOF) diagnostic is a Chemical Vapor Deposition (CVD) diamond-based detector and is the only diagnostic for measuring nuclear bang times of low yield (< 1013) shots on the National Ignition Facility (NIF). Recently, a comprehensive study of detector impulse responses revealed certain detectors with very fast and consistent impulse response with a rise time of < 50 ps, enabling low yield burn history measurements. At the current standoff of 50 cm, this measurement is possible with fast 14 MeV neutrons from deuterium-tritium (DT) fusion plasmas. PTOF-inferred DT burn width numbers compare well with widths inferred from the Gamma Reaction History (GRH) diagnostic on mid-yield (1013 − 1015) shots, where both systems are capable of making this measurement. These new capabilities could be extended to 2.5 MeV DD neutrons from D plasmas and to even lower yield by reducing the detector standoff distance to 10cm; a design for this is also presented.