Application of the coincidence method for measurements of short life periods

Abstract

A method is described for the determination of short radioactive and nuclear life periods. It consists in varying the length of the electrical impulses produced in a coincidence arrangement of two Geiger-Müller counters. The method can be used for the measurement of life periods in the range 10 -7 to 10 -1 sec. The half-life period of radium C' has been measured in this way and found to be 1.45(± 0.05) x 10 -4 sec. Experimental evidence has been obtained for the absence of γ -rays in the transition radium C' →radium D, and some conclusions regarding the lifetimes of excitation states of radium C' have been drawn. The determination of the intensity of weak sources and of the efficiency of Geiger counters for various types of radiation is described. The effect of a time lag in Geiger counters on the measurement of coincidences is discussed.