Development Of A 4? Phoswich Detector For Measuring

Internal and external radiation can cause various hazards to the human body.They can cause serious damage to human organs and systems,and lead to various diseases.Radiation protection is an important work of medical physics researchers.For the measurement of radioactive inert gases in nuclear power sites is the most effective measure to prevent radiation hazards among employees in the nuclear industry.In this paper,we successfully developed a set of 4? phoswich detector that can measure the activity of radioactive inert gases and have ?-? discrimination capabilities.The detector is mainly composed of a front laminated probe,a preamplifier,and a data acquisition system.The detector probe adopts a 47? phoswich structure,which is mainly composed of a hollow cylindrical plastic scintillator EJ-200 with an inner wall thickness of 1mm and an outer layer of a cesium iodide scintillator Cs(Tl)cylinder with a wall thickness of 20mm.The two bottom surfaces of the cylindrical scintillator are coupled with photomultiplier tubes(Photo Multiplier,PMT)for photoelectric signal conversion.The detector uses the ?-? pulse shape discrimination method for signal processing.According to the different energy deposition and pulse shape of ? and ? rays in plastic scintillator and cesium iodide scintillator,the RC constant of the preamplifier was repeatedly adjusted,and the appropriate RC constant was determined to be 30ns;the long gate value was determined to be 800ns,The short gate value is 48ns and the threshold is 40 LSB.The fitting method is used to find the relationship between the ratio coefficient of the plastic scintillator signal and the cesium iodide signal and the long gate value in the integrated charge value of the signal long and short gates,so as to solve the ? and ?signals and realize the ?-? discrimination.Using(3 ray and internal conversion electrons emitted by the 137Cs soutrce to calibrate the energy of the plastic scintillator,the energy emitted by the 137Cs source to calibrate the energy of the plastic scintillator,the energy calibration curve of the ? ray is obtained by using 133Ba and 137Cs sources to calibrate the energy of the CsI(T1)scintillator to obtain The energy calibration curve is that the linear dynamic range of the detector can be obtained from 30keV to 650keV according to the energy curves of ? and ? rays.