Distributed Radiation Sensor with Flexible Light Guide filled with Liquid Organic Scintillator

Position sensitive detectors with optical fibers (e.g. scintillating fiber, normal optical plastic fiber, liquid light guide) have been developed for a long range distributed radiation sensing to monitor nuclear facilities, because they have great advantages like long lengths, flexibility in configuration, immunity to electromagnetic fields. However, there are some problems to apply these detectors in the high-level radiation environments. In order to improve the limitation of these optical fibers, we have proposed to use a liquid light guide filled with liquid organic scintillator, because the liquid scintillator has more radiation hardness than the solid fibers and also is more sensitive than the liquid light guide by more numbers of emitted photons. The preliminary experiment was successfully made. From the experimental results, it is found that the position can be determined by the time-of-flight method and the position resolution of 85 cm is obtained for the collimated (Phi 5 mm) beta particles from ⁹⁰Y-⁹⁰Sr.