Detection sensitivity of time interval analysis for the determination of α-radionuclides with millisecond order lifetimes

Abstract

A selective extraction of the correlated events due to three kinds of short-lived α-decay events,216Po (145 ms),217At (32.3 ms) and215Po (1.78 ms), from other random background events were examined by using a time interval analysis (TIA) from the viewpoint of detection sensitivity. In the theoretical treatment based on the probability and statistics, it was clarified that the detection sensitivity proportionally increased with shortening half-lives in the following order,215Po>217At>216Po. In the experiments, pulses from a liquid scintillator owing to α-decay events were analyzed using a multiple TIA technique and resulted in the highest sensitivity of219Rn−215Po pairs in the actinium series. Thus, the multiple TIA method was applied to the practical determination of219Rn−215Po pairs in natural samples.