Research On Radiation Detection Performance Of LaBr₃（Ce）Scintillator

The detection performance of LaBr3(Ce)is much better than that of traditional inorganic scintillator,which has been widely concerned in the field of radiation detection.This paper mainly studies LaBr3(Ce)crystal in experiment and simulation,and compares and analyzes the difference of energy resolution of LaBr3(Ce)under different voltage,gain,counting time and distance.And after that,the paper analyzes the reason of good detection efficiency of LaBr3(Ce)through Material Studio software.Experiments mainly study relationship between the energy resolution and different voltage,different counting time,the different distance and different gain through energy resolution measurement platform,which LaBr3(Ce)detectors are excited by gamma irradiation(137Cs and 60Co).And comparing the results of simulation and experiment by MCNP.The improvement of the photomultiplier working voltage and gain,peak corresponds to the address will also increase,energy resolution will get better and better.However,with the increase of counting time,the channel address of the peak will not change and the count of the almighty peak will increase.In this case,the change of energy resolution is not obvious.and the increase of distance is positively,which correlated with the energy resolution,indicating that with the increase of distance,the energy resolution increases and the detection performance decreases.The paper applies the first principles calculation method,and applies the generalized gradient approximation method(GGA+U)based on density functional theory to analyze the energy band structure,state density and optical properties of the two kinds of crystals.The study shows that cerium ions transition from 4f orbital to 5d orbital due to doping,and the Fermi energy level of LaBr3(Ce)significantly shifts up,about 1.54 eV,resulting in a significant reduction in energy band structure of LaBr3(Ce)(0.63 eV),which is significantly smaller than the width of energy band structure of LaBr3 crystals(3.57 eV),which is conducive to producing more visible light at the same radiation energy.The energy band structure closely related to the density of state.From the perspective of optical properties,the absorlption coefficient and reflection coefficient(1 5.6 μm-1,about 12%)of LaBr3(Ce)crystals are also smaller than that of pure LaBr3 crystals(20 μm-1 about 15%),and the doping makes the absorption peak and reflection peak red shift,which is conducive to the same radiation energy,LaBr3(Ce)crystals absorb less visible light and transmit more photons.Through the above experiments and simulations,it is concluded that in the actual working process of LaBr3(Ce)detector,working conditions has a significant impact on the energy resolution of the detector.And from the analysis of molecular,LaBr3(Ce)crystal energy resolution better because as a result of the cerium ion doping,Ce transmit 4f to 5d orbital,lead to smaller band structure,and absorption peak and reflection peak occurred red shift,so under the same irradiation energy,LaBr3(Ce)crystals will absorb less visible light,deliver more photons,improve the detection efficiency of detector.