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Unfolding neutron spectra from water-pumping-injection multilayered concentric sphere neutron spectrometer using self-adaptive differential evolution algorithm

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Nuclear Science and Techniques 2021年第3期32卷 41-51页

作者： Rui Li Jian-Bo Yang xian-guo tuo Jie Xu Rui Shi Chengdu University of Technology Chengdu 610059China Sichuan University of Science and Engineering Zigong 643000China Applied Nuclear Technology in Geosciences Key Laboratory of Sichuan Province Chengdu 610059China

A self-adaptive differential evolution neutron spectrum unfolding algorithm(SDENUA)is established in this study to unfold the neutron spectra obtained from a water-pumping-injection multilayered concentric sphere neutron spectrometer(WMNS).Specifically,the neutron fluence bounds are estimated to accelerate the algorithm convergence,and the minimum error between the optimal solution and input neutron counts with relative uncertainties is limited to 10^(-6)to avoid unnecessary ***,the crossover probability and scaling factor are self-adaptively *** Monte Carlo is used to simulate the readings of the WMNS under(1)a spectrum of Cf-252 and(2)its spectrum after being moderated,(3)a spectrum used for boron neutron capture therapy,and(4)a reactor ***,the measured neutron counts are unfolded using the *** uncertainties of the measured neutron count and the response matrix are considered in the SDENUA,which does not require complex parameter tuning or an a priori default *** results indicate that the solutions of the SDENUA agree better with the IAEA spectra than those of MAXED and GRAVEL in UMG 3.1,and the errors of the final results calculated using the SDENUA are less than 12%.The established SDENUA can be used to unfold spectra from the WMNS.

关键词： Water-pumping-injection multilayered spectrometer Neutron spectrum unfolding Differential evolution algorithm Self-adaptive control

Ballistic deficit compensation method for a large-volume HPGe detector at high count rates

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Nuclear Science and Techniques 2016年第3期27卷 123-131页

作者： Chuan-Yun Xiong Ming-Zhe Liu Zhuo Zuo xian-guo tuo State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Nuclear Technology and Automation Engineering Chengdu University of TechnologyChengdu 610059China

A large-volume HPGe detector normally has a severe ballistic deficit due to its long rise time of the output *** the trapezoidal shaping algorithm adopted as a remedy to deal with the signals,the algorithm cannot fully eliminate the ballistic deficit in the case of a high counting *** resolve the problem,we propose a ballistic deficit compensation method that is based on the measurement of rise time of the signals before *** find that the ballistic deficit after trapezoidal shaping has little relation to the time constant,but shows a quadratic relationship with the rise time and has a negative correlation with the shaping *** the case of high count rates,the high resolution is handled by fitting the curve to the rise time and the amplitude deficit of the signal after shaping and by compensating for the signal amplitude after trapezoidal *** indicate that when the count rate is about 100 kcps,the resolution of Co-60 improves from traditional 2.32 up to 1.91 keV,thus reaching a higher level.

关键词：高计数率补偿方法 HPGe探测器亏损弹道大体积输出信号上升时间

Application of pole-zero cancellation circuit in nuclear signal filtering and shaping algorithm

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Nuclear Science and Techniques 2021年第8期32卷 85-94页

作者： Huai-Ping Wang Jian-Bin Zhou Xiao-Ping Ouyang xian-guo tuo Xu Hong Yi Liu Jie Yu You-xian Jin College of Nuclear Technology and Automation Engineering Chengdu University of TechnologyNo.1 East 3 RoadErxian BridgeChenghua DistrictChengdu 610059China Northwestern Institute of Nuclear Technology Xi’an 710024China Engineering Research Center of Nuclear Technology Application(East China University of Technology) Ministry of EducationNanchang 330013China

In radiation measurement and digital nuclear spectrum systems,traditional nuclear signal processing circuits in nuclear electronics have been gradually replaced by digital algorithm modules with the application of highperformance programmable hardware logic devices(such as FPGA or DSP).Referring to the digital realization method of inverse RC integral circuit systems,the function of the pole-zero cancellation(PZC)circuit was analyzed,a new modified cascade equivalent model of PZC was established,and the time-domain digital PZC(DPZC)recursive algorithm was derived in detail in this *** parameters kIand k_(D)are included in the new algorithm,where kIshould match the exponential decay time constant of the input signal to realize the pole-zero compensation,while the decay time constant of the output signal can be changed with the adjustable parameter k_(D)(which is larger than the decay time constant of the input signal).Based on the new DPZC algorithm module,two trapezoidal(triangular)shaping filters were designed and *** amplitude–frequency characteristics of the output signal of the proposed trapezoidal shaping algorithm and the convolution trapezoidal shaping algorithm were compared,with fixed peaking *** results show that the trapezoidal shaping algorithm based on DPZC can better suppress high-frequency ***,based on the Na I(Tl)scintillator(u75 mm×75 mm)detector and^(137)Cs source,the effect of the k_(D)value on the energy resolution of the DPZC trapezoidal(triangular)shaping algorithm was *** experimental results show that,with an increase in k_(D),the energy resolution of the system improved and reached the maximum when k_(D)was greater than 10,and the optimal energy resolution of the system was 7.72%.

关键词： Pole-zero cancellation C–R inverse system Trapezoidal/triangular shaping Amplitude–frequency characteristics Energy resolution

Generalization ability of a CNNγ-ray localization model for radiation imaging

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Nuclear Science and Techniques 2023年第12期34卷 53-65页

作者： Wei Lu Hai‑Wei Zhang Ming‑Zhe Liu Hao‑Xuan Li xian‑guo tuo Lei Wang Chengdu University of Technology Chengdu 610059China Sichuan University of Science and Engineering Zigong 643000China

Inγ-ray imaging,localization of theγ-ray interaction in the scintillator is *** neural network(CNN)techniques are highly promising for improvingγ-ray *** study evaluated the generalization capabilities of a CNN localization model with respect to theγ-ray energy and thickness of the *** model maintained a high positional linearity(PL)and spatial resolution for ray energies between 59 and 1460 *** PL at the incident surface of the detector was 0.99,and the resolution of the central incident point source ranged between 0.52 and 1.19 *** modified uniform redundant array(MURA)imaging systems using a thick crystal,the CNNγ-ray localization model significantly improved the useful field-of-view(UFOV)from 60.32 to 93.44%compared to the classical centroid localization ***,the signal-to-noise ratio of the reconstructed images increased from 0.95 to 5.63.

关键词： γ-Ray imaging γ-Ray localization model Convolutional neural network Spatial resolution

Simulation of an imaging system for internal contamination of lungs using MPA-MURA coded-aperture collimator

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Nuclear Science and Techniques 2021年第2期32卷 58-69页

作者： Ting Zhang Lei Wang Jing Ning Wei Lu Xiao-Fei Wang Hai-Wei Zhang xian-guo tuo Chengdu University of Technology Chengdu 610059China Sichuan University of Science&Engineering Zigong 643000China Beijing Institute of Radiation Medicine Beijing 100850China

The nuclides inhaled during nuclear accidents usually cause internal contamination of the lungs with low *** a parallel-hole imaging system,which is widely used in medical gamma cameras,has a high resolution and good image quality,owing to its extremely low detection efficiency,it remains difficult to obtain images of inhaled lung *** this study,the Monte Carlo method was used to study the internal lung contamination imaging using the MPA-MURA coded-aperture *** imaging system consisted of an adult male lung model,with a mosaicked,pattern-centered,and anti-symmetric MURA coded-aperture collimator model and a CsI(Tl)detector *** MLEM decoding algorithm was used to reconstruct the internal contamination image,and the complementary imaging method was used to reduce the number of *** full width at half maximum of the I-131 point source image reconstructed by the MPAMURA coded-aperture imaging reached 2.51 mm,and the signal-to-noise ratio of the simplified respiratory tract source(I-131)image reconstructed through MPA-MURA coded-aperture imaging was 3.98 *** the spatial resolution of MPA-MURA coded-aperture imaging is not as good as that of parallel-hole imaging,the detection efficiency of PMA-MURA coded-aperture imaging is two orders of magnitude higher than that of parallel-hole collimator *** the low activity level of internal lung contamination caused by nuclear accidents,PMA-MURA coded-aperture imaging has significant potential for the development of lung contamination imaging.

关键词： Lung internal contamination MPA-MURA Monte Carlo MLEM Spatial resolution Detection efficiency

Monte Carlo simulation for performance evaluation of detector model with a monolithic LaBr_(3)(Ce)crystal and SiPM array forγradiation imaging

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Nuclear Science and Techniques 2022年第8期33卷 163-174页

作者： Wei Lu Lei Wang Yong Yuan Ting Zhang Ge Tang Ming-Zhe Liu xian-guo tuo Jing Ning Chengdu University of Technology Chengdu 610059China Sichuan University of Science and Engineering Zigong 643000China Beijing Institute of Radiation Medicine Beijing 100850China

In recent years,LaBr_(3)(Ce)crystals and silicon photomultipliers(SiPMs)have been increasingly used in radiation *** study involved the establishment of a detector model with a monolithic LaBr_(3)(Ce)crystal and SiPM array forγ-radiation imaging on the GEANT4 *** optical process included in the detector model was defined by key parameters,such as the emission spectrum,scintillation yield,and intrinsic resolution of the LaBr_(3):5%Ce crystal,as well as the detection efficiency of the SiPM *** response of the detector model to^(57)Co flooded field irradiation was simulated and *** radiation images generated by the detector model exhibited a compression effect that was very close to that on images acquired by the physical *** spatial resolution of the simulated detector closely approximates that of the physical experiment.A detector model without the optical process was also established for comparison with a detector using the optical *** were used in a near-field modified uniform redundant array(MURA)imaging system to acquire images of a point source and a ring source of^(57)Co at the center of the field-of-view of the imaging *** spatial resolution and signal-to-noise ratio of the images that were reconstructed using the two detector models were determined and *** with the detector model without optical processes,although the images from the proposed detector model have slightly inferior signal-to-noise ratios and more artifacts,they are more consistent with the reconstructed versions of images acquired in real physical *** results confirm that the detector model can be used to design aγ-radiation imaging detector and to develop an imaging algorithm that can significantly shorten the development time and reduce the cost.

关键词： Scintillation photons Monte Carlo SiPM array Spatial resolution Monolithic LaBr_(3)(Ce)crystal

239Pu alpha spectrum analysis based on PIPS detector response function and variations with vacuum and distance

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Nuclear Science and Techniques 2017年第1期28卷 20-26页

作者： Rui Shi xian-guo tuo Huai-Liang Li Jian-Bo Yang Yi Cheng Hong-Long Zheng Provincial Key Lab of Applied Nuclear Techniques in Geosciences Chengdu University of TechnologyChengdu 610059 China Sichuan University of Science and Engineering Zigong 643000 China Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory Southwest University of Science and Technology Mianyang 621010 China

Effect factors of the absorption of the source,air,entrance window,and dead layer of a detector must be considered in the measurement of monoenergetic alpha particles,along with statistical noise and other factors that collectively cause the alpha spectrum to exhibit a well-known low-energy ***,the estabUshment of an alpha spectrum detector response function from the perspective of a signaling system must consider the various factors mentioned *** detector response function is the convolution of an alphaparticle pulse function,two exponential functions,and a Gaussian function,followed by calculation of the parameters of the detector response function using the weighted leastsquares fitting method as proposed in this *** our experiment,^(239)Pu alpha spectra were measured by a highresolution,passivated implanted planar silicon(PIPS)detector at 10 levels of vacuum and 10 source-detector *** spectrum-fitting results were excellent as evaluated by reduced Chi-square(x^2) and correlation ***,the variation of parameters with vacuum level and source-detector distance was *** demonstrate that σ,τ_1,and τ_2 exhibit no obvious trend of variation with vacuum in the range 2000-20,000 mTorr,and at a confidence level of 95%,the values of τ_1 and τ_2 decline in a similar fashion with source-detector distance by the power exponential function,while the value of a declines linearly.

关键词： Alpha spectrum Detector response function Weighted least squares PIPS detector

Unfolding analysis of LaBr3:Ce gamma spectrum with a detector response matrix constructing algorithm based on energy resolution calibration

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Nuclear Science and Techniques 2018年第1期29卷 23-31页

作者： Rui Shi xian-guo tuo Huai-Liang Li Yang-Yang Xu Fan-Rong Shi Jian-Bo Yang Yong Luo Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory Southwest University of Science and Technology Mianyang 621010 China Sichuan University of Science and Engineering Zigong 643000 China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology Chengdu 610059 China

With respect to the gamma spectrum, the energy resolution improves with increase in energy. The counts of full energy peak change with energy, and this approximately complies with the Gaussian distribution. This study mainly examines a method to deconvolve the LaBr_3:Ce gamma spectrum with a detector response matrix constructing algorithm based on energy resolution *** the algorithm, the full width at half maximum(FWHM)of full energy peak was calculated by the cubic spline interpolation algorithm and calibrated by a square root of a quadratic function that changes with the energy. Additionally, the detector response matrix was constructed to deconvolve the gamma spectrum. Furthermore, an improved SNIP algorithm was proposed to eliminate the background. In the experiment, several independent peaks of ^(152)Eu,^(137)Cs, and ^(60)Co sources were detected by a LaBr_3:Ce scintillator that were selected to calibrate the energy resolution. The Boosted Gold algorithm was applied to deconvolve the gamma spectrum. The results showed that the peak position difference between the experiment and the deconvolution was within ± 2 channels and the relative error of peak area was approximately within 0.96–6.74%. Finally, a ^(133) Ba spectrum was deconvolved to verify the efficiency and accuracy of the algorithm in unfolding the overlapped peaks.

关键词： Detector response matrix Energy resolution calibration LaBr3:Ce scintillator SNIP background elimination Boosted Gold deconvolution algorithm

Determination of Gamma point source efficiency based on a backpropagation neural network

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Nuclear Science and Techniques 2018年第5期29卷 1-9页

作者： Hong-Long Zheng xian-guo tuo Shu-Ming Peng Rui Shi Huai-Liang Li Jing Lu Jin-Fu Li Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics College of Chemistry and Environmental Engineering Sichuan University of Science and Engineering Fundamental Science on Nuclear Wastes and Environmental Safety Laboratory Southwest University of Science and Technology

Efficiency is an important factor in quantitative and qualitative analysis of radionuclides, and the gamma point source efficiency is related to the radial angle,detection distance, and gamma-ray energy. In this work, on the basis of a back-propagation(BP) neural network model,a method to determine the gamma point source efficiency is developed and validated. The efficiency of the point sources ^(137)Cs and ^(60)Co at discrete radial angles, detection distances, and gamma-ray energies is measured, and the BP neural network prediction model is constructed using MATLAB. The gamma point source efficiencies at different radial angles, detection distances, and gamma-ray energies are predicted quickly and accurately using this nonlinear prediction model. The results show that the maximum error between the predicted and experimental values is 3.732% at 661.661 keV, 11π/24, and 35 cm, and those under other conditions are less than 3%. The gamma point source efficiencies obtained using the BP neural network model are in good agreement with experimental data.

关键词： Efficiency BP neural network HPGe detector Gamma point source