Detection Performance Of NaI(Tl) And CsI(Na) Scintillator Detectors

Scintillation detector has developed into a mature method of nuclear radiation detection.Scintillation counting technology is an integral part of experimental nuclear physics.The CsI(Na)and NaI(T1)scintillator detectors have long fluorescence duration,high energy resolution,and can more accurately measure radiation and determine nuclides.With the use of scintillator detector in various working environments,its shortcomings are gradually exposed,and the complex operating environment also makes the performance of the detector been affected.Therefore,the energy resolution and detection efficiency of scintillator detectors under different conditions are very important research subjects.At the same time,it is easy to introduce noise while using scintillator detector.Therefore,according to the advantages and disadvantages of scintillator detectors and different operating environment,we adopt the method of reducing detector noise to optimize our detection results.At the same time,in order to measure two particles in the mixed radiation field of alpha and gamma more accurately,these particles must be discriminated.This paper presented the non-linear energy resolution properties of sealed NaI(T1)and Csi(Na)detectors under ?-rays(137Cs and 60Co)excitation by using experimental and Monte Carlo simulation methods.We sealed the NaI(T1)and CsI(Na)detectors and measured the energy resolution properties in different photomultiplier(PMT)voltages by using multiple channels analysis system.The experimental results showed that the energy spectrum peaks shifted with the input high voltage on the photomultiplier increasing,the best energy resolution rates of 2-inch NaI(T1)and 2-inch CsI(Na)and 3-inch NaI(T1)detectors were 7.25%,7.29%and 8.48%respectively when the PMT voltage was 625V.But the best energy resolution rate of 1.5*8-inch NaI(T1)detector was 7.17%when the PMT voltage was 600V.We established the simulation models of the experimental NaI(T1)and Csl(Na)detectors and simulated their energy spectra.The simulation results agreed with the experimental energy spectra.The simulation energy resolution rates of the 2-inch NaI(T1)and 2-inch CsI(Na)and 3-inch NaI(T1)and 1.5*8-inch NaI(T1)detector detector models came out to be 1.2%,7.28%,8.38%and 7.22%respectively.In addition,we calculated the relative full-energy peak efficiency of NaI(T1)and CsI(Na)detectors,and experimental results showed that the input high voltage did not have effect on full-energy peak efficiency of detectors,and the larger crystals can lead to better detection efficiency.Also,we investigated the pulse shape processing performance of the CsI(Na)scintillator by using the root mean square error(RMSE),because the CsI(Na)crystal presents different decay time characteristics when excited by a(239Pu)and y(137Cs)particles.The pulse waveform is denoised by Matlab software,and the pulse waveform of alpha particles is removed in frequency domain.At the same time,by fitting the descending edge of the pulse waveforms,it is found that it can satisfy the form of exponential function.The similarity between the fitting function and the descending edge of the pulse waveform is calculated(expressed by root mean square error,RMSE),and the RMSE can be well distinguished into two groups.While using a fitting curve,the events with 0.02<RMSE<0.2 were due to a particles while the events with 0.4<RMSE<0.6 were due to y particles.While using ? fitting curve,the events with 0.4<RMSE<0.6 were due to y particles,the events with 0.7<RMSE<0.85 were due to y particles.