Possibility of nuclear reaction product identification by avalanche counters

A device with an avalanche counter has been developed to measure flight time of nuclear reaction products with heavy ions. The avalanche counter consists of a plano-parallel condenser, plates of which are two organic films with thin Au layers deposited on them. Primary ionization of molecules occurs when passing a particle through a gas volume, and electrons arising in this case in a strong electric field cause collision ionization. Rapidly rising signal of electron avalanche is used for time markings. The counter is placed in a steel chamber with input and output vacuum windows separating the gas volume of the counter (pressure from 5 to 20 torr) from high vacuum in a reaction chamber and ionic conductor. Device specifications were tested at the JINR U-300 cyclotron by means of 136Xe ions accelerated up to 112 MeV as well as by means of α particle source. Avalanche counter time resolution was equal to approximately 370 ns. The experiments show that the device using the avalanche counter may be used as a ''time zero'' counter for measuring charged particle flight time (including also fission fragments), and as a thin AE counter