The Study Of Complex Detector For γ-β Discrimination

The Study of complex detector forγ-βdiscriminationThe normalization of international radiation safety demands that in important nuclear facility, monitoring radioactive aerosol must be performed, which is of important signification not only for measuring online, controlling pollution status effectively in workshop and insuring health of personal, but also for detecting hidden trouble in nuclear facility in time and disposing the trouble immediately. the radiation of nuclear power station results from the nuclear fission of nuclear fuel. in the containment of nuclear power plants, the main elements of radioactive are the outcome of ingredient of stainless steel pipe activated by neutron, such as Cr,Mn,Fe,Co,Ni etc. They tend to come back stabilization after havingβdecay, companied by emittingγ. So the level of grossβradioactive aerosol in the containment of nuclear plants can indicate the radioactive pollution state of the containment; moreover, it can provide evidence which indicate whether there is the phenomenon of leak in the first circuit system's pressure boundary. The count of grossβis influenced byγcompanied byβdecay. In order to decrease the influence ofγ, we design complex detector forγ-βdiscrimination. In the front of the detector, thin plastic scintillation is used to detectβ, and a littleγ, also is detected. Behind it , BGO is used to detectedγ. Through nuclear electronic technology, we can discriminate the signals from plastic scintillation and BGO, because they have different light attenuation coefficient. We can counteract the count ofγin plastic scintillation by using the count ofγin BGO. Compared with traditional methods using semi conductor detector, in the front of the detector, it is of advantages such as long longevity excellent ability enduring tough working conditions.The thesis introduces the safe monitoring principle of the radioactive aerosol in detail. The function ofγdetection efficiency is obtained. Based on MATLAB and MCNP4C, the parameters of the detector's dimension are achieved. Meantime, thorough analysis is given to the relation between the time constant of output circuit and pulse shape. The graphs of relation between the time constant of output circuit and pulse shape are drafted. The effect caused by slow ingredient of light in plastic scintillation on pulse shape is also touched on; it can lead to the delay of the maximal height and decrease in height, but few effects are imposed on discrimination on pulse shape.