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核技术（英文版）
核技术（英文版）

马余刚

双月刊

1001-8042

LHB@sinap.ac.cn

021-59553998-331

201800

上海市800-204信箱

核技术（英文版）/Journal Nuclear Science and TechniquesCSCDCSTPCD北大核心SCI
查看更多>>本刊是中国核学会会刊，由国内外核研究领域的著名科学家组成编委会。它刊登理论、实验和应用核物理，放射化学和辐射化学，核测量方法和仪器，核能与石材料科学、生命科学、农业、地球和环境科学方面的应用，是中国在核研究领域中唯一的一份英文期刊。发表的论文为国际六大著名检索期刊中的五个所收录。
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    CMOS direct conversion X-ray detector coupled with fluorinated liquid

    Shi-Hua LiuChao-Song GaoXin ZhangXiang-Ming Sun...
    1-10页
    查看更多>>摘要：X-ray detectors show potential applications in medical imaging,materials science,and nuclear energy.To achieve high detection efficiency and spatial resolution,many conventional semiconductor materials,such as amorphous selenium,cadmium telluride zinc,and perovskites,have been utilized in direct conversion X-ray detectors.However,these semiconductor materials are susceptible to temperature-induced performance degradation,crystallization,delamination,uneven lattice growth,radiation damage,and high dark current.This study explores a new approach by coupling an FC40 electronic fluorinated liquid with a specialized high-resolution and high-readout-speed complementary metal-oxide-semiconductor(CMOS)pixel array,specifically the Topmetal Ⅱ-chip,to fabricate a direct conversion X-ray detector.The fluorinated liquid FC40(molecular formula:C21F48N2)is an electronic medium that is minimally affected by temperature and displays no issues with uniform conductivity.It exhibits a low dark current and minimal radiation damage and enables customizable thickness in X-ray absorption.This addresses the limitations inherent in conventional semiconductor-based detectors.In this study,simple X-ray detector imaging tests were conducted,demonstrating the excellent coupling capability between FC40 electronic fluorinated liquid and CMOS chips by the X-ray detector.A spatial resolution of 4.0 lp/mm was measured using a striped line par card,and a relatively clear image of a cockroach was displayed in the digital radiography imaging results.Preliminary test results indicated the feasibility of fabricating an X-ray detector by combining FC40 electronic fluorinated liquid and CMOS chips.Owing to the absence of issues related to chip-material coupling,a high spatial resolution could be achieved by reducing the chip pixel size.This method presents a new avenue for studies on novel liquid-based direct conversion X-ray detectors.
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    A single-pixel elemental imaging method using neutron-induced gamma-ray activation

    Can ChengYong-Ji XieXun-Rong XiaJia-Yu Gu...
    11-22页
    查看更多>>摘要：Neutron-induced gamma-ray imaging is a spectroscopic technique that uses characteristic gamma rays to infer the elemen-tal distribution of an object.Currently,this technique requires the use of large facilities to supply a high neutron flux and a time-consuming detection procedure involving direct collimating measurements.In this study,a new method based on low neutron flux was proposed.A single-pixel gamma-ray detector combined with random pattern gamma-ray masks was used to measure the characteristic gamma rays emitted from the sample.Images of the elemental distribution in the sample,comprising 30 × 30 pixels,were reconstructed using the maximum-likelihood expectation-maximization algorithm.The results demonstrate that the elemental imaging of the sample can be accurately determined using this method.The proposed approach,which eliminates the need for high neutron flux and scanning measurements,can be used for in-field imaging applications.
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    In situ measurement of environmental γ radiation dose rates of key nuclides for large radioactive surface sources

    Ze-Qian WuJian SunWei-Qi HuangBai-Rong Wang...
    23-33页
    查看更多>>摘要：To monitor nuclear and radiation emergencies,it is crucial to obtain accurate in situ measurements of the environmental y radiation dose rate from key radionuclides,particularly for large radioactive surface sources.The methods currently used for measuring dose rates are inadequate for obtaining the dose rates of key radionuclides and have large angular response errors when monitoring surface sources.To address this practical problem,this study proposes three methods for measur-ing the dose rate:the weighted peak total ratio,mean value regression,and numerical integration methods.These methods are based on energy-spectrum measurement data,and they were theoretically derived and numerically evaluated.Finally,a 1-m-long hexagonal radioactive surface source was integrated into a larger surface source.In situ measurement experiments were conducted on a large radioactive surface source using a dose-rate meter and a portable HPGe y spectrometer to analyze the errors of the three aforementioned methods and verify their validity.
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    Positron annihilation study of defect formation and evolution in matrix graphite under He ion irradiation

    Hong-Xia XuJian-Dang LiuBang-Jiao YeZi-Wen Pan...
    34-42页
    查看更多>>摘要：The stability of matrix graphite under neutron irradiation and in corrosive environments is crucial for the safe operation of molten salt reactors(MSRs).Raman spectroscopy and a slow positron beam were employed to investigate the effects of He ion irradiation fluences and subsequent annealing on the microstructure and defects of the matrix graphite.He ions with 500 keV energy and fluences ranging from 1.1 ×10 15 ions/cm2 to 3.5×10 17 ions/cm2 were used to simulate neutron irradiation at 300 K.The samples with an irradiation fluence of 3.5×10 16 ions/cm2 were subjected to isochronal anneal-ing at different temperatures(573 K,873 K and 1173 K)for 3 h.The Raman results revealed that the D peak gradually increased,whereas the intrinsic G peak decreased with increasing irradiation fluence.At the same irradiation fluence,the D peak gradually decreased,whereas the intrinsic G peak increased with increasing annealing temperature.Slow positron beam analysis demonstrated that the density or size of irradiation defects(vacancy type)increased with higher irradiation fluence,but decreased rapidly with increasing annealing temperature.The Raman spectral analysis of sample cross sections subjected to high irradiation fluences revealed the emergence of amorphization precisely at the depth where ion damage was most pronounced,whereas the surface retained its crystalline structure.Raman and positron annihilation analyses indicated that the matrix graphite exhibited good irradiation resistance to He ions at 300 K.However,vacancy-type defects induced by He ion irradiation exhibit poor thermal stability and can be easily removed during annealing.
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    Systematic experimental investigation on pressure build-up characteristics of water-jet injection into a molten LBE pool

    Hao-Ran HuangZi-Jian DengSong-Bai ChengJia-Yue Chen...
    43-56页
    查看更多>>摘要：In the scenario of a steam generator tube rupture accident in a lead-cooled fast reactor,secondary circuit subcooled water under high pressure is injected into an ordinary-pressure primary vessel,where a molten lead-based alloy(typically pure lead or lead-bismuth eutectic(LBE))is used as the coolant.To clarify the pressure build-up characteristics under water-jet injection,this study conducted several experiments by injecting pressurized water into a molten LBE pool at Sun Yat-sen University.To obtain a further understanding,several new experimental parameters were adopted,including the melt tem-perature,water subcooling,injection pressure,injection duration,and nozzle diameter.Through detailed analyses,it was found that the pressure and temperature during the water-melt interaction exhibited a consistent variation trend with our previous water-droplet injection mode LBE experiment.Similarly,the existence of a steam explosion was confirmed,which typically results in a much stronger pressure build-up.For the non-explosion cases,increasing the injection pressure,melt-pool temperature,nozzle diameter,and water subcooling promoted pressure build-up in the melt pool.However,a limited enhancement effect was observed when increasing the injection duration,which may be owing to the continually rising pressure in the interaction vessel or the isolation effect of the generated steam cavity.Regardless of whether a steam explo-sion occurred,the calculated mechanical and kinetic energy conversion efficiencies of the melt were relatively small(not exceeding 4.1％and 0.7％,respectively).Moreover,the range of the conversion efficiency was similar to that of previous water-droplet experiments,although the upper limit of the jet mode was slightly lower.
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    Study on the off situ reconstruction of the core neutron field based on dual-task hybrid network architecture

    Pei CaoHui DingCheng-Long CaoZi-Hui Yang...
    57-73页
    查看更多>>摘要：The off situ accurate reconstruction of the core neutron field is an important step in realizing real-time reactor monitoring.The existing off situ reconstruction method of the neutron field is only applicable to cases wherein a single region changes at a specified location of the core.However,when the neutron field changes are complex,the accurate identification of the individual changed regions becomes challenging,which seriously affects the accuracy and stability of the neutron field recon-struction.Therefore,this study proposed a dual-task hybrid network architecture(DTHNet)for off situ reconstruction of the core neutron field,which trained the outermost assembly reconstruction task and the core reconstruction task jointly such that the former could assist the latter in the reconstruction of the core neutron field under core complex changes.Furthermore,to exploit the characteristics of the ex-core detection signals,this study designed a global-local feature upsampling module that efficiently distributed the ex-core detection signals to each reconstruction unit to improve the accuracy and stability of reconstruction.Reconstruction experiments were performed on the simulation datasets of the CLEAR-I reactor to verify the accuracy and stability of the proposed method.The results showed that when the location uncertainty of a single region did not exceed nine and the number of multiple changed regions did not exceed five.Further,the reconstructed ARD was within 2％,RDmax was maintained within 17.5％,and the number of RD≥l0％was maintained within 10.Furthermore,when the noise interference of the ex-core detection signals was within±2％,although the average number of RD≥10％increased to 16,the average ARD was still within in 2％,and the average RDmax was within 22％.Collectively,these results show that,theoretically,the DTHNet can accurately and stably reconstruct most of the neutron field under certain complex core changes.
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    A nuclide identification method of γ spectrum and model building based on the transformer

    Fei LiChu-Yang LuoYing-Zi WenSheng Lv...
    74-87页
    查看更多>>摘要：In current neural network algorithms for nuclide identification in high-background,poor-resolution detectors,traditional network paradigms including back-propagation networks,convolutional neural networks,recurrent neural networks,etc.,have been limited in research on y spectrum analysis because of their inherent mathematical mechanisms.It is difficult to make progress in terms of training data requirements and prediction accuracy.In contrast to traditional network paradigms,network models based on the transformer structure have the characteristics of parallel computing,position encoding,and deep stacking,which have enabled good performance in natural language processing tasks in recent years.Therefore,in this paper,a transformer-based neural network(TBNN)model is proposed to achieve nuclide identification for the first time.First,the Geant4 program was used to generate the basic single-nuclide energy spectrum through Monte Carlo simulations.A multi-nuclide energy spectrum database was established for neural network training using random matrices of γ-ray energy,activity,and noise.Based on the encoder-decoder structure,a network topology based on the transformer was built,transforming the 1024-channel energy spectrum data into a 32 × 32 energy spectrum sequence as the model input.Through experiments and adjustments of model parameters,including the learning rate of the TBNN model,number of attention heads,and number of network stacking layers,the overall recognition rate reached 98.7％.Additionally,this database was used for training AI models such as back-propagation networks,convolutional neural networks,residual networks,and long short-term memory neural networks,with overall recognition rates of 92.8％,95.3％,96.3％,and 96.6％,respectively.This indicates that the TBNN model exhibited better nuclide identification among these AI models,providing an important reference and theoretical basis for the practical application of transformers in the qualitative and quantitative analysis of the y spectrum.
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    A novel method for simultaneous measurement of 222Rn and 220Rn progeny concentrations measured by an alpha spectrometer

    Zhong-Kai FanJia-Le SunHao-Xuan LiXiang-Ming Cai...
    88-100页
    查看更多>>摘要：The accumulation of 222Rn and 220Rn progeny in poorly ventilated environments poses the risk of natural radiation exposure to the public.A previous study indicated that satisfactory results in determining the 222Rn and 220Rn progeny concentrations by measuring the total alpha counts at five time intervals within 560 min should be expected only in the case of high progeny concentrations in air.To complete the measurement within a relatively short period and adapt it for simultaneous measurements at comparatively lower 222Rn and 220Rn progeny concentrations,a novel mathematical model was proposed based on the radioactive decay law.This model employs a nonlinear fitting method to distinguish nuclides with overlapping spectra by utilizing the alpha particle counts of non-overlapping spectra within consecutive measurement cycles to obtain the concentrations of 222Rn and 220Rn progeny in air.Several verification experiments were conducted using an alpha spectrometer.The experimental results demonstrate that the concentrations of 222Rn and 220Rn progeny calculated by the new method align more closely with the actual circumstances than those calculated by the total count method,and their relative uncertainties are all within±16％.Furthermore,the measurement time was reduced to 90 min,representing an acceleration of 84％.The improved capability of the new method in distinguishing alpha particles with similar energies emitted from 218Po and 212Bi,both approximately 6 MeV,contributed to realizing more accurate results.The proposed method has the potential advantage of measuring relatively low concentrations of 222Rn and 220Rn progeny in air more quickly via air filtration.
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    Optical transmittance and pulse shape discrimination of polystyrene/poly(methyl methacrylate)-based plastic scintillators

    Yi-Yao LiangYing-Du LiuPu-Sen WangJie Bao...
    101-109页
    查看更多>>摘要：Polymethyl methacrylate(PMMA)is an optically transparent thermoplastic with favorable processing conditions.In this study,a series of plastic scintillators are prepared via thermal polymerization,and the impact of PMMA content on their transparency and pulse shape discrimination(PSD)ability is investigated.The fabricated samples,comprising a polysty-rene(PS)-PMMA matrix,30.0 wt％2,5-diphenyloxazole(PPO),and 0.2 wt％9,10-diphenylanthracene(DPA),exhibit high transparency with transmissivity ranging from 70.0 to 90.0％(above 415.0 nm)and demonstrate excellent n/y discrimination capability.Transparency increased with increasing PMMA content across the entire visible light spectrum.However,the PSD performance gradually deteriorated when the aromatic matrix was replaced with PMMA.The scintillator containing 20.0 wt％PMMA demonstrated the best stability concerning PSD properties and relative light yields.
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    Observation and mechanism of non-uniform distribution of tin nuclei in preparing vapor diffusion coated Nb3Sn thin film for SRF applications

    Shuai WuYang YeZi-Qin YangYuan He...
    110-122页
    查看更多>>摘要：Growth of high-quality Nb3Sn thin films for superconducting radiofrequency(SRF)applications using the vapor diffusion method requires a uniform distribution of tin nuclei on the niobium(Nb)surface.This study examines the mechanism underlying the observed non-uniform distribution of tin nuclei with tin chloride SnCl2.Electron backscatter diffraction(EBSD)analysis was used to examine the correlation between the nucleation behavior and orientation of niobium grains in the substrate.The findings of the density functional theory(DFT)simulation are in good agreement with the experimental results,showing that the non-uniform distribution of tin nuclei is the result of the adsorption energy of SnCl2 molecules by varied niobium grain orientations.Further analysis indicated that the surface roughness and grain size of niobium also played significant roles in the nucleation behavior.This study provides valuable insights into enhancing the surface pretreatment of niobium substrates during the growth of Nb3Sn thin films using the vapor diffusion method.
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