Study Of Gammaray Spectrometer Based On SiPM-scintillation Detector

With development of nuclear energy,radiation monitoring plays a more and more important role in environment.As a major radiation monitoring technology,?-ray detected has a great significance in field of radiation protection,nuclear medicine,nuclear technology and application.Scintillation detector is one of the most common monitors to detect?-ray.The wide use of scintillation detector puts forward new requirements such as compact structure,low power dissipation,high mechanical strength,low dark noise,insensitive magnetic field for photon electrical devices.Comparing to p-i-n?PIN?photodiode and photomultiplier tube,silicon photomultiplier are more accordant with those requirements.The silicon photomultiplier?SiPM?is a new type of photo detector consisting of avalanche photodiode arrays operated in Geiger mode.It has the advantages of small volume,low operating voltage,insensitive magnetic field,high single photon resolution.To research different scintillators photocoupling performance with SiPM light out,A system of Gamma-Ray Spectrometer based on SiPM-Scintillation Detector has been build.GEANT4 toolkit is used to simulate NaI?TI?and La Br3:10%Ce3+scintillation crystal detect?-ray photocoupling with SiPM by building a complete Monte Carlo model of a scintillator includes ionizing particle and optical photon transport.The results of simulation which were written into Root files in the form of Tree data model.As one effective simulation method for particle transport,the application of Monte Carlo method was limited by too long computation time.To solve this problem,the application of importance sampling was studied in the paper.The amplifier adapter circuit of SiPM is designed.It has good output signal when circuit structure and component parameters are optimized.The ORTEC NIM spectrometer as digital spectrometer is use to collect,shape,filter signal.The gamma spectrum is studied by detecting?-ray of ¹⁵²Eu,¹³⁷Cs standard source in different environment.Simulation results show that energy resolution of gamma spectrum is in accordance with the result of experimental measurement and confirms the reliability and rationality of material properties and parameters which set in GEANT4 toolkit.The temperature response,magnetic properties,radiation resistance,efficiency,linearity and energy resolution are analyzed.The energy resolution and non-proportionality characteristics are very close to those measured with the PMT.Comparing to scintillation detector with PMT light out,this monitor system is more suitable for portable instrument and stationary in narrow space.