Development of new -ray measurement methods with radon suppression focused on pulse time interval

Sanada, Yukihisa   ; Nohara, Naofumi*; Adachi, Yasuyuki*; Nemoto, Kazuhiko*; Kawai, Keiichi*; Kobayashi, Hirohide ; Hashimoto, Tetsuo*

An -ray measurement methods based on analyzing the time interval of pulses was newly developed. This method was developed aiming to suppress the background counts originated in progeny of uranium series. A delayed coincidence and time interval analysis (TIA) methods have been applied to measure a-b decay successive events (correlated events) on microsecond time-scale (164s). The measurement system have such functions with silicon detectors was developed intending to shorten the dead time. The basic performance of the system was examined by using Th electrodeposited sources. Follows were obtained in this work : The theory of measurement Po using TIA methods was established. Measurement system of Po was developed. Conformation methods of correlated events by using Th electrodeposited sources was suggested. The efficiency of correlated events in aerosol samples was estimated. The methods to measure correlated events was indicated by addition of Th. The method of subtracting the progenies of the thorium series are to examine.