| With the rapid development of science and technology, nuclear energy in the medical, industrial, energy and other fields is more and more widely used, but the nuclear safety and the environment in the nuclear radiation has also been more and more attention. Most of the radionuclides have the potential to emit gamma rays with specific energy. The gamma rays emitted by different radionuclides are not the same, but the energy of the gamma ray has a strong penetrating ability, so it is very important for the detection of gamma rays in the environment. Among them, NaI (TI) crystal detector has become the most basic instrument for measuring the radiation of radioactive material. It has the advantages of high detection efficiency, low cost, convenient use, etc., and is widely used in nuclear radiation monitoring. The NaI (TI) crystal detector is used to characterize the results. The accuracy of the spectrum is directly determined by the detector efficiency, and the detection efficiency is determined by the detector.In this paper, the Nal (TI) crystal is studied by Monte Carlo method. The method can be directly from the actual physical point of view, and it also has a strong ability to deal with geometric and cross section.7Be,137Cs,54Mn,65Zn,60Co,, 478661.62834.5611141332.481367.9kev, Geant4, and 24Na were detected by the simulation program. According to the data obtained from the calculation, the detection efficiency function, peak to total ratio, energy resolution, response function and the corresponding experimental data were compared. The results were consistent with the results obtained by the experimental data. The feasibility of the program was verified.Because the detector is the ultimate collection of photons generated by gamma ray interactions in the crystal, the number of photons collected more or less directly affect the scintillation detector detection index. And the photon collection is by photoelectric crystal scintillation detector is connected with the back-end of photomultiplier tube collection, so we analyze the NaI (TI) crystal shape is different the number of photons collected will influence. According to NaI (TI) scintillator crystal shapes are researched. The combination of Monte Carlo simulation and Geant4, we build a simulation system design and optimization of the concept of a scintillation detector. Complete simulation framework includes the basic components of a practical scintillation detector system, and includes all relevant physical processes, from gamma rays and scintillator materials interaction to digitally processing generated by sampling ADC, the detector signal. In the simulation of the complete, individual physical factors will affect the detector system performance, such as scintillator geometry, surface finish, scintillator decay time, scintillation yield, PMT single electron response (SER) and the front end of the electrical response, will be taken into account. The main purpose is to complete the simulation parameters to understand the physical process and all the basic ingredients in a scintillation detector in the system affect its performance. In the simulation, we set up four groups of different shapes of NaI (TL) crystal, in addition to different shapes of crystals outside, the rest of the conditions are the same, and under the same conditions to detect crystals are used wrapped with Teflon material. Through comparing and analyzing the statistical data, we found that crystal shape different for photomultiplier tube to collect gamma rays produced photon number has certain influence, which scintillator crystal shape is designed to provide theoretical guidance. |
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