Study On Multi-Grid Neutron Detector Substituting ~3He Tube

At present,the ³He gas supply is tight,the price is very expensive.Research and development of alternative ³He neutron detector has became a hot spot in the research field.Multi-Grid is a new kind detector which¹⁰B₄C coated as conversion layer,aluminum as the base material,argon and carbon dioxidemixture as working gas.It is one of the most important alternative to ³He detection technology.The grid detector has the advantages of high detection efficiency,good position resolution,large area expansion,strong gamma suppression ability and low production cost,and its comprehensive performance is equivalent to that of the ³He detector.In this paper,Monte Carlo method is used to calculate the performance parameters of the detector,and use ²⁵²Cf neutron source test the readout electronics of Multi-Grid neutron detector.Three commonneutron conversion materials were calculated using Geant4,the conversion efficiency increases then decreases with the change of thickness of the transition layer,combined with the material properties determine the conversion layer material and optimization thickness.By calculatingthe range and energy deposition of charged particles from nuclear reaction,it is found that the charged particles will deposit most of the energy in the working gas,then to optimize the size of the detector.Using Garfield++to calculate the gain of detector under different anode wire diameter,and gain of detector under differentgas score,when the detector voltage is determined,the smaller of anode wire diameter,the biger of gain,the lower of the quenching gas score,the bigerof gain,determine the final detector working gas and anode type and diameter.The whole detection process by neutron incident to avalanche electron is collected was simulated by Geant4Garfieldinterface,The positions of the avalanche electrons collected on the anode wire are obtained.Through the experimental test data acquisition system of Multi-Gridgas neutron detector,according to the test results of the data acquisition system to modify the parameters,and then determine the optimal parameters ofdata acquisition system.Experiments show that,data acquisition system meets the application requirements of Multi-Grid detector.