Detection properties of the electret pulse chamber

The detection properties of the electret ionization chamber in the pulse mode are described for an air-filled chamber with parallel plate geometry. The chamber consists of an one-sided metallized PTFE electret connected with a charge sensitive preamplifier. Irradiation of the air volume with α-particles as well as of a polyethylene-walled chamber with fast neutrons gives rise to pulse generation. The charge carriers generated in the air volume are attracted by the electric field of the electret and collected on the electret surface lowering its surface potential, initially charged up to 2 kV. The pulse rate decreases nearly proportionally with the electret voltage as a function of increasing irradiation time. Neither gamma nor β-radiation caused pulses but lowered the electret voltage. (orig.)