| There are mixed radiation fields composed of n-γ,β-γ,α-γ and other different rays in nuclear industrial sites.At present,the mature product of particle screening measurement in mixed radiation field is mainly aimed at n-γ and α-γ mixed field,while the detection technology of β-γ mixed field mostly stays in the field of scientific research,and there is no mature product.Based on the Phoswich detector,a new multilayer scintillation β-γ detector was developed by our research group.In this paper,through theoretical simulation,we study the fluorescence signal generated by the deposition energy of each layer of scintillation,and invert the deposition energy of incident particle events in each layer of scintillation.By judging whether the signal logic is "100","110" and "001",we can achieve a higher screening rate of β-γ mixed field accuracy.Among them,the fluorescence collection efficiency is closely related to the accurate inversion of the deposition energy of particles in scintillator,which determines whether the logical judgment can be carried out effectively,and is a key factor affecting the feasibility of screening measurement technology and prototype development.Based on Geant4,this paper explores the influence of fluorescence collection mode,scintillation size and type on multi-layer scintillation detector.At the same time,combined with the actual technology,the prototype is manufactured and part of the test is carried out.The work of this paper is as follows:1)The fluorescence transmission efficiency of three fluorescence collection methods,"scintillator + optical fiber + photoelectric conversion device","scintillator+ optical conductor + photoelectric conversion device" and "scintillator +Si PM array",was calculated.The simulation results showed that the optimal fluorescence collection method was "scintillator +Si PM array".2)The effects of the second and third layer scintillator materials and thickness of the multi-layer scintillator detector,as well as the size of the detector detection end face on the fluorescence transmission efficiency were simulated.The simulation results showed that the optimal detector structure was "0.5 mm plastic scintillator" + "18 mm plastic scintillator" + "20 mm inorganic scintillator".3)The principle prototype is processed and some of its performance is tested.It is found that the experimental measurement is in good agreement with the theoretical simulation data,indicating that the fluorescence simulation study in this paper can provide a reliable theoretical basis for the detector fluorescence collection. |
