A new method of determining half-value periods from observations with a single Geiger counter

Abstract
A coincidence circuit is described which makes possible the determination of half-value periods between 10 -4 sec. and 1 sec. using a single Geiger counter. This arrangement has been used to determine the half-value periods of actinium A, thorium A and radium C' with the following results: AcA ( 1·83 ± 0·04) x 10 -3 sec., ThA (1·58 ± 0·08) x 10 -1 sec., RaC ' (1·48 ± 0·06) x 10 -4 sec. A discussion of the limitations of the method and of possible sources of error is given.