| The thesis studies the phenomenon of photoelectronic drifting which is caused by NaI(TI) scintillator crystal detector's temperature variation and the study is based on 137 Cs's energy spectrum of 662KeVγ.The experiment method is H·Dewaard's which looks on the photoelectric peak as gaussian distribution curve, that means the axis of symmetry of curve, as the channel address, corresponds to the reference peak of photoelectric peak and the peak is divided into two parts by selecting one channel address from the reference peaks respectively. The photoelectric drifting can be concluded by counting differential value of the two parts and stabilizing the peak can be realized by remodeling the gain of PMT.The microcomputer, as the designed peak stabilization circuit according to the theoretical model, can ensure the collecting and processing the signal under the same temperature and the signal processing can immediately reflect the status of the scene by integrated design of combining the detector and the peak stabilization circuit. The electric components are all low power consumption and low temperature coefficient ones. The experiment realizes the mathematic function of AN,drifting magnitude, and B, digital controlling signal outputed by microcomputer and the automatic controlling programme is based on the function, too.The experiment shows that the device can judge the drifting direction correctly and control the voltage of PMT. Between-10℃and 50℃, the accuracy error of 137Cs is±3 channel addresses. The device is very suitable for industrial online testing and field measurement for its smaller size and lower expense. |
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