Trigger circuit for time of flight-detectors using pulsewidth encoding

A trigger circuit for a microchannel plate detector within a time-of-flight mass spectrometer has been designed, providing high time resolution and low dead time. Independent of input amplitude the output pulse of this trigger circuit shows an ECL (emitter coupled logic) compatible amplitude and a constant pulsewidth t_w (e.g., t_w=5 ns) for a single event. Performing pulsewidth encoding, a double event with a time separation Δt at the input of the trigger circuit generates an output pulse with a pulsewidth t´_w=t_w+Δt , if Δt is less than t_w. Otherwise, this double event is treated as two single events. Due to temperature compensation the pulsewidth remains nearly constant over a wide temperature range from -25°C to 100°C. Due to a compact design the trigger circuit is mounted directly into the vacuum system at the microchannel plate detector without any transmission line in between