A proportional counter system with small wall effect

The wall effects interfering with low energy measurements with proportional counters using gaseous sources are discussed, and a new type of counter in which they are considerably reduced is described. A layer of gas surrounding the sensitive volume is turned into a separate detector by a multiwire counting system which prevents escaping electrons or X-rays being registered. Applications to a new measurement of the L/K-capture ration of ^(71)Ge, and to low level counting, are described