One-dimensional position-sensitive detector for alpha particles using an outer-layer scintillating fiber

For applications of detecting alpha contamination and identifying its location over a wide area at a time in nuclear plants and radiation facilities, a position-sensitive detector for alpha-rays based on an outer-layer scintillating (OLS) fiber with silicon photomultiplier (SiPM) readout was developed. While a standard scintillating fiber is unable to detect alpha-rays due to their short range, the OLS fiber has a thin scintillation layer on its surface that enhances its potential for alpha-ray measurements. We initially performed measurements using an Am-241 source to compare the alpha-ray-detection capability of the OLS fiber with that of a conventional scintillating fiber. Subsequently, a position-sensitive detector employing the time-difference method was developed to measure the radiation distribution along the fiber in a one-dimensional format. The time and spatial resolutions of the measurement system, which used a single 2.2-m-long fiber, were estimated to be approximately 3.6 ns and 290 mm full width at half maximum (FWHM), respectively. Results from two Am-241 sources placed simultaneously indicated that the resolving capability to distinguish the two sources of the measurement system was <300 mm.