A Geiger Counter for Beta-Rays

Abstract

A Geiger counter for beta-rays is described that is easy to construct and has the low back-ground count of two per minute. Two modifications are in use, one in which the rays are admitted through an aluminum foil supported by a copper grid; and the other in which the material to be tested is placed directly within the chamber. The characteristics of various gases are discussed; it is shown that while organic vapors tend to lower the background count they also lower the sensitivity. A simple method for measuring the counter efficiency for rays of different energies is outlined.