Prebreakdown gas tube detector of near UV radiation based on photoionization of excited states: Time response to short N₂ laser pulses

A near ultra-violet gas-filled detector which is operated in the prebreakdown regime is described. 300 ps N₂ laser pulses were used to study experimentally the detector speed of response at the 337 nm wavelength. Relative response times for different gases seem to be consistent with the photoionization of excited gas states, which is the basic mechanism of detection. Of the various rare gases, argon yielded the shortest response time. Both photoionization-assisted electron heating and secondary emission seem to play a significant role in reducing the time response. The reduced work function of the cathode material also appears to contribute to the reduced time response.