The application of alternate polarity HT fields to neon flash tubes

In preliminary tests on small diameter high pressure flash tubes filled with Ne and He (70-30) and 2% of methane, using the e+ test beam facility at the Daresbury Laboratory, it was found that the flash tube digitization pulse heights decreased with increasing rate. Further investigations of the digitisation pulse height with rate has been carried out using positive and negative polarity ht pulses. The decay constant of the internal clearing field have been found to be 0.6 and 27.7 s for positive and negative applied fields respectively. The sensitive times for positive and negative applied fields have been measured to be 26.5 μs and 7.0μs respectively. A new high voltage pulsing system has since been developed for applying fields of opposite polarity alternately. The tests using this new pulsing system and a 106Ru source have been very successful and it is seen to greatly reduce the effects arising from internal clearing fields. The digitisation pulse heights are found to remain fairly constant up to a rate of 90 min-1. The results of these tests are reported here. (Auth.)