Modern detectors for radiation monitors

Abstract

SiO 5 (Ce), CdTe, and HgI 2 , microtubes from organic scintillators, nanomaterials, and detectors based on gaseous and solid-state electronic multipliers are examined. A comparison is made of conventional detectors based on NaI(Tl) and CsI(Tl), plastic scintillators, and 3 He counters. The advantages of the new detectors are better energy resolution, high detection efficiency, low supply voltage, processing convenience, and cost. These detectors will increase the sensitivity of radiation monitors in monitoring unauthorized transport of nuclear and other radioactive materials, identify in real time the materials being monitored, and simplify the detecting apparatus and the development of monitors.Radiation monitors are a tool for monitoring unauthorized transport of nuclear and other radioactive materials. The main components of a monitor are neutron, x-ray, and γ-detectors. The main characteristic of radiation monitors depends on their efficiency -the detection threshold of the materials being monitored.The detectors developed on the basis of the new materials -LaBr 3 , Bi 4 Ge 3 O 12 , CdWO 4 , LiI(Eu), ZnO, Lu 2 SiO 5 (Ce), CdTe, and HgI 2 , microtubes from organic scintillators, and ultrapure germanium -have better characteristics than conventional detectors. The advantages of the new detector are better energy resolution, high detection efficiency, low supply voltage, processing convenience, and cost. Some new possibilities have already been realized in serial or trial production, and many are known only from individual publications.The present article presents the modern detectors, which can replace conventional detectors for developing radiation monitors and make it possible to increase their sensitivity, identify monitored materials in real time, and simplify the detection apparatus. x-and γ-Ray DetectorsInorganic scintillators. Conventional detectors are those based on NaI(Tl) and CsI(Tl) single crystals [1]. About 25 eV is expended on the formation of one photon. The luminescence spectrum agrees well with the spectral sensitivity of photocathodes of most vacuum photomultipliers. A single crystal is transparent to its own radiation and is simple to make. Its drawback is high hygroscopicity and brittleness. The temperature dependence of the volume is also important. These properties are important for developing radiation monitors operating under normal climatic conditions. The light output reaches its maximum value at room temperature, and it drops sharply at 0 and above 60°C. A decrease of temperature is accompa-