Influence of water and ethanol vapors on the operation of air proportional counters

Influence of water and ehtanol vapors was examined on the operation of cylindrical air proportional counters. These vapors depositing on the anode wire of the counter emitted a large amount of positive ions into the counter volume by a high electric field at the anode. The positive ion emission, however, never generated spurious pulses to be detected. The decrease of counting efficiency for β-rays observed by the addition of these vapors to the air could be explained by the decrease of the effective volume of the counter, which was generated by the promotion of three-body attachment of electrons to oxygen molecules. It was clarified that spurious pulses observed with the air containing these vapors were entirely due to the generation of leakage current through the surface of an insulator. (orig.)