A study on the bundle-type scintillating fiber and tapered scintillator radiation sensors for monitoring of radioactive wastes disposal sites

Several types of gamma-ray sensors were constructed by packing different numbers of fibers into aluminum tubes, and tested to detect the 137Cs gamma ray. It has been found from this investigation that tapered fibers can be more efficient to collect the lights produced inside the sensor and transfer them into the transmitting fiber. In order to predict the functioning of the tapered fiber, tapered plastic scintillators, composed of polystyrene with minute amount of dPOPOP and PPO or dPBD, were fabricated and tested for the detection of gamma rays from 1.0, 1.5, 3.0. 5.0 μCi 137Cs sources, and the pulse height spectrum and the relationship between the radioactivity and the total counts are analyzed. It has been found from this study that the tapered scintillating optical fiber, if manufactured, can be practically applied to the development of gamma-ray sensors which can be deployed in μCi-level radiation fields