Research Of Gamma Ray Source Localization Technology Based On Scintillation Detector

With the wide spread applications of radioactive sources and radiation devices, meanwhile the probability of radiation accidents caused by sources become larger. Therefore, how to locate and safely find those radioactive sources which had been lost is quite important.It is quickly to get the radioactive source's direction by detecting the direction of incoming gamma rays, which is easy to measurement and make sure searchers keep safe distance away from the lost radioactive source. Therefore, it is a better way of locating and finding the lost radioactive sources effectively and safely that design a detector which is able to detect the direction of incoming gamma rays.In this paper, the main work of the research of the gamma ray source localization technology based on the scintillation detector includes the following two parts:The first part: Research of gamma ray source localization technology based on NaI scintillation detector1. The design of NaI(sodium iodide) collimating detector of gamma localization search, simulated and analyzed the influences by MCNP5 software from thicknesses of the shielding ball, gamma ray energy, length of collimating detector, collimator thickness, source distance which would low gamma ray angle resolution down of plumbum-collimation NaI detector. Also MCNP5 simulated the location of radioactive source and analyzed the influences of multiple radiation sources of leading collimating NaI detector locating capability. The simulation results show that when the length of collimating detector is 9.5cm, the angularresolution of the plumbum-collimation NaI detector close to 2 degrees,high precision of positioning simulation, errors of radiation source that detected twice within 3 meters are 0.0421 m and 0.0585 m. Moderate weights, functioning in radiation field of mult-radioactive sources to locating each radiation source.2. The design of the triangular-cylinder-plumbum-shield NaI detector and verified with experiments. Experimental analysis of the direction of the detector response, introducing four times measurement method that simplifies the measurement procedure, improves positioning efficiency and accuracy. Experimental analysis had been done for the factors of time measurement, plumbum shielding thickness, a radioactive source distance effects of radiation source localization accuracy and efficiency, and the radiation source localization experiments.Experimental results show that for 5 × 5uci 137 Cs source, detector distance of 50 cm to 70 cm, the maximum angle deviation for 1.17 degrees and 0.69 degrees respectively in measurement within 30 s. For 137 Cs source, the air absorbed dose rate is ?0.028uGy/h, the average angle deviation from air-sorption is ?1.24 degrees. For 5×5uci 137 Cs source,positioning deviation within the distance of 1.5m is about 0.097 m.The second part: Three crystal coupling gamma ray direction detector positioned gamma radiation sourceThe design and Simulation of the three crystal coupled gamma ray detector are completed, and the influences of the related parameters on the angle resolution of the detector is calculated. Simulation 1m distance of 137 Cs source angle resolved maximum deviation is less than 1o;Analysis of the cylindrical lead core radius and cylindrical crystal scintillation probe diameter and height on the angle of the detectorresolution, optimal lead core radius value is 1.5cm, cylindrical crystal scintillation probe diameter and height value 9cm and 7cm, the detection efficiency of the detector with the probe diameter and height increase increased, maximal angular deviation is less than 1 degree, the diameter and the highly desirable 7.5 cm and 5 cm; Three crystal coupled gamma ray direction detector's localization deviation is about 0.023 m when detects 137 Cs source from 1m.The above results can provide reference for the location of uncontrolled radioactive sources.