ELECTRON TRANSIT LAGS IN GEIGER COUNTERS
NEW YORK UNIV NY COLL OF ENGINEERING
Pagination or Media Count:
Measurements were made of the transit time of an electron from the cathode to the central wire of a self-quenching Geiger counter. The electron was ejected from the cathode wall by light from an HV spark. The light from this spark also fell on a vacuum photocell and gave an electrical pulse, the beginning of which indicated zero time. The time interval between the beginning of this pulse and the beginning of the electrical pulse from the Geiger tube is shown to be the transit time of the photoelectron in the Geiger tube. This time interval, called the time lag, was measured by a delayed coincidence circuit. The time lag was found to be distributed about a most probable value under given conditions, according to a Gaussian, or Poisson distribution law. The half-width of the distribution was about 0.07 microsec for all of the counters tested. All of the counters contained argon and 1 of the following organic vapors ETOH, Et2O, petroleum ether, or amyl acetate. The partial and total pressures of the filling constituents, the cathode diameter, and the overvoltage were varied during the measurements. The time lag was between 0.45 and 0.95 microsec in all filling for the smaller size counters except where Et2O was used. The lags in the Et2O fillings were slightly shorter. A new formula was calculated for electron transit times in accordance with recent measurements of electron mobilities in Geiger counter filling mixtures.
- Nuclear Instrumentation