Fractional charge collection technique for pile-up reduction - counting low intensity radiation in presence of intense gamma-ray and neutron background

Abstract

Properties of a fractional charge collection technique for pile-up reduction in large volume NaI(Tl) crystals have been investigated for the particular use of measurement of whole body nitrogen by in vivo neutron activation analysis. The resolution of the system and the photomultiplier anode pulse length has been measured as a function of pulse clipping times. A comparison between conventional voltage mode and the fractional charge collection mode has been made from the point of view of pile-up effect. The performance of the system has been tested in our application to a total count rate of 2×10 5 pulses/s.