最新刊期
      卷 0 ， 期 0 ， 2020
      • XIONG Yun1,2 YAN Yingbing1 LENG Yongbin1 YI Xing1,2 LAI Longwei1,2 WANGBaopeng1,2 ZHANG Ning1,2 1
        Vol. 35, Issue 2, (2012)
        摘要：In this paper,we report our work on the software and hardware architecture of the DCCT system for SSRF where top-up mode is being used.Matlab is used to simulate two methods of beam current calculation.The system resolution of the DC current measurement with 2 Hz system bandwidth could be better than 0.38 μA when arithmetic mean of whole cycle algorithm is applied.The beam lifetime calculation algorithm is optimized to use two points in the curve fitting procedure based on the characters of the top-up mode.The algorithm of finding the confidence level is also discussed and is verified to be accurate in data prediction as well as fast in convergence by using the practical data fetched in the laboratory.The flow chart of the software layer is given to show how the code is implemented.  
        关键词：Beam current;Beam lifetime;Data prediction algorithm;DCCT system;Top-up;SSRF   
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        发布时间：2021-03-05
      • ZHOU Zhizhong HU Shouming WANG Jun GUO Honglei SU Haijun
        Vol. 35, Issue 2, (2012)
        摘要：Voltage stability and precision are key specifications of an electron beam irradiator.A voltage control system was developed for smooth high voltage regulating on a power frequency electron accelerator.Pillar variac driven by servo motor was used as the regulating device,with a programmable logic controller as the control unit.An industrial PC was employed to realize human-machine interaction.Open-loop and closed-loop modes were employed to regulate the high voltage.Experimental results show that the speed,stability and precision for high voltage regulating were improved greatly,hence a much better performance of the electron accelerator.  
        关键词：Regulate voltage;Programmable controller(PLC);FM353;Servo motor   
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        发布时间：2021-03-05
      • LENG Chongyan1 ZHOU Rong1 ZHANG Xu2 1
        Vol. 35, Issue 2, (2012)
        摘要：Ti6Al4V alloy samples were modified by tantalum ions implantation at the doses of 1.2×1016,3×1016,1.5×1017,3×1017 and 4.5×1017ions/cm2,with an acceleration voltage of 146.5 keV.Potential-dynamic polarization technology was used to investigate corrosion resistance of the Ta+-implanted Ti6Al4V alloy samples in Hank’s solution.Glancing angle X-ray diffraction and X-ray photoelectron spectroscopy were used to characterize of the implanted samples in terms of the phase composition and chemical states of the surface elements,respectively.The Ta ion implantation improves corrosion resistance of Ti6Al4V alloy.However,corrosion current density of the implanted samples was not in a monotonic way of decrease with increasing ion doses.The corrosion resistance improvement of Ta+-implanted Ti6Al4V alloy samples in Hank’s solution is attributed to the corrosion-resistant oxide layer,surface alloy layer produced in the ion implantation,and the Ta in outmost surface of the implanted alloy.  
        关键词：Ti6Al4V;Tantalum ion implantation;Corrosion resistance   
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        发布时间：2021-03-05
      • XU Nannan1 LI Gongping1,2 WANG Yunbo1 ZHONG Huoping1 LI Tianjing1 GONG Hengfeng1 WANG Baoyi3 LI Zhuoxin3 1
        Vol. 35, Issue 2, (2012)
        摘要：Rutile single-crystal TiO2were irradiated by 2.5 MeV neutrons from D-D reaction on a neutron generator at Lanzhou University.Positron annihilation lifetime spectra and X-ray diffraction(XRD) patterns of the irradiated samples were compared with those of the virgin.Considering the fact that the threshold displacement energy of titanium atoms is almost two times of that of oxygen atoms,more oxygen vacancies(VO) would be produced than that of titanium vacancies(VTi) under the neutron irradiation.Lifetime results indicated that the irradiated samples had larger electron density of titanium vacancies than the virgin rutile,as a result of increased oxygen vacancies surrounding the Ti vacancy,because of the coulombic repulsion.From the XRD results,distance along the c-axis shrank slightly and the crystallinity became weaker after the neutron irradiation.  
        关键词：Single-crystal TiO2;D-D neutron;Radiation damage;Positron   
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        发布时间：2021-03-05
      • XI Shanbin1,2 LU Wu1 WANG Zhikuang3 REN Diyuan1 ZHOU Dong1,2 WEN Lin1 SUN Jing1 1
        Vol. 35, Issue 2, (2012)
        摘要：Radiation damage,caused by high or low dose rate irradiation,to NPN transistors of different oxide thicknesses is investigated experimentally.The results show that base current of the transistors increased with total dose,but the current gain decreased with increasing total dose.The NPN transistors of thin oxides degraded more than those of ordinary oxide thickness.However,both types of the NPN transistors exhibited the enhanced low dose rate sensitivity(ELDRS).Mechanisms of the effects are discussed.  
        关键词：NPN bipolar transistor;60Co γ-irradiation;Oxide thickness;ELDRS   
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        发布时间：2021-03-05
      • CHEN Jingmin LI Yongqiang XIONG Zhengye WANG Wenhua FENG Yujun HUANG Cunyou TANG Zhao SHI Wenqing
        Vol. 35, Issue 2, (2012)
        摘要：To select thermoluminescent dosimeters(TLDs) for low radiation research,thermoluminescence responses of Al2O3:C,LiF:Mg,Ti and LiF:Mg,Cu,P were measured under natural radiation background in Zhanjiang city,China.TL sensitivity of the three TLDs,in terms of the threshold dose,is sequenced as Al2O3:C(1~2 μGy),LiF:Mg,Cu,P(about 2 μGy),and LiF:Mg,Ti(>10 μGy).However,as the temperature of glow peak of Al2O3:C is not so high,its TL decays in a relatively long period,hence the non-linearity of the TL dose response curve of Al2O3:C,while temperatures of glow peaks of LiF:Mg,Ti and LiF:Mg,Cu,P are higher,hence their linear TL dose response.Therefore,LiF:Mg,Cu,P is the best TLD for low radiation cumulative dose detection.  
        关键词：Thermoluminescence(TL);Natural background radiation;Al2O3;LiF   
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        发布时间：2021-03-05
      • DANG Xiaojun YU Chunrong WEI Mengfu ZHANG Lianping WU Lunqiang
        Vol. 35, Issue 2, (2012)
        摘要：Quick identification of the location,distribution and quantity of radioactivity is of great interest in nuclear safety.Gamma camera is mainly used to acquire two dimensions radioactive images.Radioactive 3D distribution reconstruction using 2D image is a promising technique to identify radioactive location and distribution.In this paper,we propose a physical model in radioactive 3D distribution reconstruction after studying gamma camera imaging process.The model was validated by ML-EM reconstruction method.  
        关键词：Gamma camera;3D distribution;Physical model   
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        发布时间：2021-03-05
      • CHEN Yanzhou SUN Guangai CHEN Bo
        Vol. 35, Issue 2, (2012)
        摘要：If stress-free sample is measured near surface by residual stress neutron diffractometer,shift of diffraction peak position(pseudo shift) will be introduced due to intrinsic properties of diffractometer.In order to improve accuracy of stress measurement,suitable methods to reduce the pseudo shift are necessary.In this paper,methods for reducing the pseudo shift are systematically investigated by ray-tracing program SIMRES.The results indicate that wavelength and peak clipping effects can be depressed by primary and secondary radial collimators,respectively.In this way the pseudo shift is effectively reduced.  
          
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        发布时间：2021-03-05
      • HE Shanzhen1 WANG Shuxia11 WANG Peng1 ZHAI Chuanyan1 ZHOU Zhiling2 1
        Vol. 35, Issue 2, (2012)
        摘要：In this work,we focused at establishing an efficient and rapid method of high-performance liquid chromatography-tandem mass spectrometry(HPLC/MS/MS) for quantitative analysis of Kryptofix 2.2.2 as 18F-FDG tracer.K-222 and internal standard were chromatographically separated on an ultimate XB-C18 column(Φ4.6 mm ×150 mm,3 μm) with a mobile phase containing 40 mmol/L ammonium acetate buffer and acetonitrile(50:50) at a flow rate of 0.85 mL.min–1.The electronic spray ion tandem mass spectrum with the positive mode and multitude reaction monitor(MRM) were used to detect K-222 in [18F]FDG..The linear range of calibration curves was 0.5–120 ng.min–1for K-222,with the intrabatch and innerbatch variations of <9.4%.The recovery rate ranged from 101.3% to 106.6%.The study indicated that the present method was rapid(less than 4 min),sensitive,efficient,and reliable,being suitable for detecting K-222 in18F-FDG.  
          
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        发布时间：2021-03-05
      • WANG Xuetao1,2 CHEN Shaowen3 DAI Zhenhui2 ZHU Lin2 LIU Xiaowei1 1
        Vol. 35, Issue 2, (2012)
        摘要：With the gantry angles of 0° 80° and 280° 360°(0°),the off axis distance(OAR) profiles curves of 6 MV X-ray were obtained by Monte Carlo simulation,3-D water phantom measurement and MatriXX measurement.Comparing the three types of curves,we analyzed the angular dependence of MatriXX 2-D chamber array.The results revealed that the three types of curves agreed well with the gantry angles of 0° 60° and 300° 360°(0°).Curves and centre point dose on plane from Monte Carlo simulation differed obviously from those of MatriXX measurement in gantry angles of 70° 90° and 270° 290°.It is possible to verify the dose distribution of intensity modulated radiation therapy(IMRT) plan using the Multi-Gantry-Angle Composite(MGAC).  
        关键词：Angular dependence;Intensity modulated radiation therapy;Dose verification   
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        发布时间：2021-03-05
      • FAN Ruirui LIANG Xiaohua MENG Xiangcheng
        Vol. 35, Issue 2, (2012)
        摘要：In this paper,we report a laboratory DAQ system based on VME bus,for applications in nuclear physics and the detector tests.It uses a commercial ADC card and a single board computer as a crate controller.They are based on the VME bus.The software is based on the ROOT framework.A canvas window is employed for online monitoring,and the acquired data are stored as Histograms in a ROOT file.The data acquisition speed can rea MB/s.A spectrum of 241 Am 59 keV γ-ray collected with a CdZnTe detector is shown to demonstrate the system.  
        关键词：VME bus;ROOT;DAQ   
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        发布时间：2021-03-05
      • YANG Feng1,2 QIAO Weiming1 ZHANG Wei1 LI Guihua1 AN Shi1 GU Kewei1 WU Jiongqi1 JIANG Ziyun1 CHENG Yun1 1
        Vol. 35, Issue 2, (2012)
        摘要：The control system of HIRFL-CSR magnet power supply should be improved.In order to realize the complex control algorithms based on modern control theory,digital controller of the power supply was designed with ARM+FPGA architecture.State-space equation solver was designed in the FPGA to realize the state feedback control of the power supply.The results show that the dynamic response speed,steady state accuracy and robustness of the control system are greatly improved.  
        关键词：HIRFL;Switching power supply;Digital controller;FPGA;State feedback;State-space equation solver   
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        发布时间：2021-03-05
      • NIU Dongxiao HU Jun
        Vol. 35, Issue 2, (2012)
        摘要：In this paper,conductive atomic force microscope(c-AFM) is employed to investigate the conductance of composite structure of reduced graphene oxide(rGO) and double strand DNA molecule on isolated mica substrate,in torsional resonance tunneling current mode.The results indicate that graphene trends to absorb double strand DNA molecules to form composite body,and the c-AFM detections indicate that such a composite body is ineffective in long distance electron transfer,due to the high electric resistance of DNA.This work is of significance for explorations of applying graphene and DNA into molecular devices,and our measurement method is of practical value.  
        关键词：c-AFM;Graphene;DNA;Electron transfer;Molecular device   
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        发布时间：2021-03-05
      • WU Yuting1,3 ZHANG Wenmei1 LI Xiaowei2 ZHAO Hongwei3 1
        Vol. 35, Issue 2, (2012)
        摘要：Telomeres are closely related to cell aging,death and canceration.Guanine-rich and cytosine-rich strands of human telomeric DNA can form G-quadruplex and I-motif conformation,respectively.These conformations have relations with telomerase activity,centromeric DNA structures,RNA intercalated structures,having been an attractive drug target for cancer chemotherapy and for modulation of gene transcription.In this paper,key factors to the formation of different conformations are studied by using circular dichroism spectrum(CDS).The results show that the formation of dAG3(T2AG3)3 into G-quadruplex is greatly affected by metal ions,while the I-motif structure of d(C3TA2)3C3T depends largely on pH values.It is easy to form WC duplex structure in the equimolar mixture of dAG3(T2AG3)3and d(C3TA2)3C3T,however,G-quadruplex and I-motif can both exist under certain conditions.  
        关键词：Telomeres;DNA;Circular dichroism spectrum;Metal ions;pH   
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        发布时间：2021-03-05
      • DU Xiaoguang ZHANG Jun GUAN Jishi
        Vol. 35, Issue 2, (2012)
        摘要：Designing an in-core neutron flux measurement is not an easy task,due to long design and manufacturing period,and difficulties in purchasing key machinery and debugging the control system.Based on the RSView32 software,we developed a simulation system to simulate the function of electrical equipment and machinery;with real time monitoring.Implementation of the system is described in the paper.Test results showed that the simulation system can substitute the electrical equipment and machinery in designing an in-core neutron flux measurement system,and the control system can work with the simulation system.Application of simulation system in an NPP project reduces the mechanical wearing and the system test time.  
        关键词：In-core neutron flux instrumentation system;Simulation;RSView32   
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        发布时间：2021-03-05
      • YANG Bin NIU Shengli LUO Xudong HUANG Liuxing
        Vol. 35, Issue 2, (2012)
        摘要：Based on shell theory of debris and interactions between debris and atmospheric molecules at high altitudes,a method was developed to model HANE debris movement under the effect of geomagnetic field and atmosphere.The charge-exchange section item and collision-ionization section item in the magnetohydrodynamic equation showed the stop action of atmosphere.The Lagrangian differential method was applied to solve the magnetohydrodynamic equation of debris motion in the geomagnetic field.Debris cloud expansion of a typical high altitude detonation was simulated.Expansion scale,velocity,pressure and temperature of early debris in deferent direction were given.  
          
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        发布时间：2021-03-05
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