最新刊期
      卷 38 ， 期 12 ， 2015
      • XIAO Yongchuan,OUYANG Huafu,XUE Kangjia,LIU Shengjin,CAO Xiuxia,LYU Yongjia,HUANG Tao
        Vol. 38, Issue 12, Article number: 120201(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120201
        摘要：Background: A Radio Frequency Quadruple (RFQ) accelerator was developed for China Spallation Neutron Source (CSNS). Purpose: The aim is to design a 3-MeV, 20-mA H? RFQ accelerator. Methods: Lots of careful investigations, analysis, experimental tests were performed to solve the problem that came out in design and machining process. Results: The machining tolerance of RFQ measured by three-Coordinate Measuring Machine (CMM) was less than 20 μm; the unloaded Q value was 7 679, about 80% of the theoretical Q value; the flatness of RF electric field distribution was higher than 2.5% after several time tuning. After several days conditioning, the power feeding into the cavity reached 450 kW and maintained for 12 h without sparking. Negative hydrogen ion beam with energy of 3 MeV and current of 28 mA at the exit of RFQ was gotten in the beam commissioning afterwards. Conclusion: The current commissioning results of RFQ meets the requirement of CSNS, and the beam current can be improved in future. Abstract  
        关键词：RFQ;High power RF conditioning;Flatness of RF electric field distribution;CSNS   
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        发布时间：2021-03-03
      • JIANG Yifeng,LUAN Weiling,ZHANG Xiaoni,HAN Yanlong,SUN Ke
        Vol. 38, Issue 12, Article number: 120202(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120202
        摘要：Background: The corrosive, highly radioactive and humid-hot environment in nuclear power plant requires an overall performance for neutron shielding material. Purpose: This study aims to develop a new type of AFG90-H epoxy resin-based neutron shielding composite which would tolerate high temperature in a complex environment. Methods: The preparation of the composite materials is doped functional particles into the epoxy resin matrix, and the composite was tested for its radiation resistance, high temperature mechanical properties, neutron shielding and corrosion resistance. Results: In the 42-kGy radiation environment, with the glass transition temperature reaching 262 oC, the bending strength of the composite declined by only 1.63%, which showed better neutron shielding performance than common materials such as high density polyethylene (HDPE), paraffin and 6002 epoxy resin (EP). By adding the B4C particles, the neutron shielding performance and temperature mechanical properties of the composite were improved greatly, and the corrosion resistance performance did not degrade. Conclusion: Due to its excellent performance in temperature, corrosion and radiation resistance, as well as its low density, this composite could be used as the neutron shielding layer for mobile detection equipment. Abstract  
        关键词：Neutron radiation;Shielding;Temperature resistance;Composite materials   
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        发布时间：2021-03-03
      • CHEN Cheng,LI Dan,LAI Wanchang,WANG Guangxi,ZHAI Juan,HONG Ziqiang
        Vol. 38, Issue 12, Article number: 120203(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120203
        摘要：Background: X-ray fluorescence (XRF) determination of elements in atmospheric PM2.5 has the advantages of being fast and nondestructive, but it is a complicated problem for the selection and preparation of standard sample. Purpose: The aim is to introduce a standard sample preparation of Pb element determination in PM2.5 by XRF which is a simple, cheap, accurate and reproducible method for preparing the sample. Methods: The thin sample was prepared with the help of drip Pb standard method, and the feasibility of the hydrophilic polytetrafluoroethylene (PTFE) membrane as a carrier material was discussed. The metal ions with PTFE of strong hydrophobicity and low adsorption were chosen as sample preparation slab. After the discussion on the relationship between droplet volume and the reproducibility of sample preparation, the best droplet volume for sample preparation reached 0.3 mL. The standard sample of Pb element analysis of PM2.5 was prepared by using above methods. Results: The working curve of Pb was established with the linear correlation 0.996, which was of good accuracy and precision. The detection limit was 35 ng?cm?2. Conclusion: Using the working curve, Pb content in the atmosphere in April, 2015, in Chengdu city is analyzed. The results showed that the concentration range of Pb in PM2.5 was 0?526 ng?cm?3, and the average concentration of Pb in the nighttime was higher than that in the daytime. Abstract  
        关键词：XRF analysis;Standard sample;PM2.5;Pb   
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        发布时间：2021-03-03
      • XIAO Caijin,ZHANG Guiying,YUAN Guojun,JIN Xiangchun,YAO Yonggang,HUA Long,WANG Pingsheng,NI Bangfa
        Vol. 38, Issue 12, Article number: 120204(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120204
        摘要：Background: Delayed neutron counting (DNC) is a rapid and accurate uranium determination method applied in many fields, such as geology, materials, and nuclear safeguards. Purpose: Usually the method is done as following, one sample is irradiated by reactor neutrons for 60 s, then transferred to a position waiting for delayed neutron counting, which starts after 30 s from the end of irradiation for a counting time of 60 s. The routine of DNC may lead to some problems. For example, when the uranium concentration of a sample is very high, some delayed neutron counts would be lost. On the contrary, when the uranium concentration of a sample is too low, the counting statistics would be very poor. Methods: A standard curve method was proposed to solve the problem. Results & Conclusion: Preliminary experiments show that this method is suitable for the determinations of uranium in samples with a wide range of uranium concentrations. Abstract  
        关键词：Delayed neutron;Uranium determination;Standard decaying curve   
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        发布时间：2021-03-03
      • SHAN Feng,FU Peng,HUANG Liansheng,GAO Ge
        Vol. 38, Issue 12, Article number: 120401(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120401
        摘要：Background: International Thermonuclear Experimental Reactor (ITER) is the largest superconducting Tokamak device in the world. CODAC (Control, Data Access and Communication) system has been adopted as the central control system for ITER device. This system provides ITER subsystems with many tools to design and develop its own sub-control system. ITER device will produce a larger number of experimental data during its operation. Fast data acquisition and large volume of data can bring great difficulty to control system. Purpose: This study aims to design and implement a data archiving system for Poloidal Field (PF) control to archive these data effectively in time, and provide some way to check the data. Methods: Data Archiving Network (DAN) of CODAC is employed to implement an effective data archiving system for ITER PF control system, and a program to do data lookup is designed using Python. Necessary experiments to simulate the PF system were performed to test this data archiving system flexibly. Results and Conclusion: Experimental results show that this data archiving system can store experimental data effectively. Abstract  
        关键词：ITER;CODAC;HDF5;Data archiving;DAN   
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        发布时间：2021-03-03
      • XUE Qian,ZENG Yun,ZHANG Jie
        Vol. 38, Issue 12, Article number: 120402(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120402
        摘要：Background: Silicon pixel detector for synchrotron radiation is a new device designed for the technical need of X-ray detection of Beijing advanced light source. The entire detector is placed in a radiation environment, and the multiple frontend readout boards are placed in sealed cooling containers, thus the traditional Universal serial bus - joint test action group (USB-JTAG) cables can no longer be used. Purpose: This study aims to design and implement remote updating and debugging multi-Field programmable gate array (multi-FPGA) for the detector without opening the cooling container. Methods: In this study, a network based ARM microcontroller was used to accept configuration files via network and generate JTAG sequence to FPGA by means of Xilinx visual cable (XVC) protocol. Results: The remote updating and debugging of multi-FPGA were realized. Conclusion: This method improves the reliability of remote updating and debugging of FPGAs and is easy to extend with less extra circuits. Abstract  
        关键词：Silicon pixel detector;XVC protocol;ARM;JTAG interface;TCP/IP;Remote update and debugging   
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        发布时间：2021-03-03
      • MA Siyuan,FENG Changqing,SHEN Zhongtao,WANG Qi,LIU Shubin,AN Qi
        Vol. 38, Issue 12, Article number: 120403(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120403
        摘要：Background: Bismuth Germanate (BGO) calorimeter is the key sub-detector of the Dark Matter Particle Explorer (DAMPE) satellite. There are extensive tests including the performance testing of 40 Front-end Electronics (FEE) in the engineering development model and flight model, the LED source calibration of 1600 Photomultiplier Tubes (PMT) and different kinds of ground environment simulation test as long as several months during production. Purpose: This study aims to ensure the progress of production by developing a ground test system to meet the demand for automated data collection and command parameters during the experiments and tests. Methods: First of all, the testing requirements were analyzed in details, then a framework of hardware and software was designed according to available resources. Finally the software was implemented and optimised by means of LabWindows/CVI and virtual instrument technology to fulfil all test functionalities. Results: The user interface (UI) and function modules of the software meet the requirements of data acquisition and automatic control for the BGO calorimeter of DAMPE satellite. Conclusion: This testing system has been put into practical application for more than 18 months, successfully reduced the working strength and improved the test efficiency. Abstract  
        关键词：DAMPE;BGO calorimeter;LabWindows/CVI;Virtual instruments   
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        发布时间：2021-03-03
      • QU Hongguang,HEI Dongwei,LI Binkang,TIAN Xiaoxia,WANG Jing,LI Haitao
        Vol. 38, Issue 12, Article number: 120404(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120404
        摘要：Background：The lower measure limit of radiation pulse detection is usually about hundred-μA lever due to various kinds of noise existed in electronic system. However, some detectors could get the small pulse signal at the lever of decade nA and keep the noise at the lever of nA. Therefore, the conventional detection system would not collect these weak signals. Purpose: This study aims to design and implement a radiation detection system to overcome lower limitation of detection and improve the linearity of measurement for large dynamic pulse signals. Methods: The detection system noise was analyzed to explore the lower measure limit in a wide system bandwidth range. Based on the design of low noise amplifier circuit and highly dynamic digital transmission system, it could confirm the low measure limit through the theories of a small capacitor’s output is in a linear correlation with input. Improvement was made according to experimental testing. Results: The system could process the weak pulse signals in the range of 0.8–680μA (peak) with 20MHz bandwidth. A γ-radiation pulse signal below 1μA with the LSO (Lu2SiO5)+PMT (photo multiplier tube) radiation detector was successfully obtained by experiment. Conclusion: The new radiation detection system constituted with low-noise broad-band amplifier and highly dynamic digital transmission system was useful in expanding the system measure range to improve the system detection efficiency. Abstract  
        关键词：Radiation detection;Low noise;Bandwidth;Low measure limit;Digital transmission   
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        发布时间：2021-03-03
      • ZHANG Huan,WANG Siguang,CHEN Wei,YANG Shanchao
        Vol. 38, Issue 12, Article number: 120501(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120501
        摘要：Background: Reactor neutron can induce single event upset (SEU) in Static Random Access Memory (SRAMs). Local metal interconnection is widely used in modern complementary metal oxide semiconductor (CMOS) technology. The most frequently used local materials are some heavy metals, such as tungsten (W) or copper (Cu). These metals could affect the neutron induced SEU in CMOS. Purpose: The relationship between SEU cross section and critical energy (Ec) can be referred by SEU experiments with reactors. Methods: The SEU cross sections with different Ec of a SRAM are simulated and calculated using Geant4 with a reactor neutron spectrum, and SEU induced by 1?14 MeV neutrons are also simulated in structures with and without a tungsten layer. Results: The relationship between SEU cross section σ (in unit: cm2) and Ec (in unit: MeV) is σ=exp[?18.7×Ec?32.3]. In the structure with a tungsten layer, SEU cross sections induced by 1?3 MeV neutrons are increased because a few α particles are created. Conclusion: To reduce neutron SEU cross section, the critical energy of CMOS should be increased as high as possible, and usage of tungsten should be avoided. Abstract  
        关键词：Single event upset;Reactor neutron;Heavy metal;GEANT4   
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        发布时间：2021-03-03
      • DU Liangliang,LI Quan,LI Shaoxian,HU Fangrong,XIONG Xianming,ZHANG Wentao,HAN Jiaguang
        Vol. 38, Issue 12, Article number: 120502(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120502
        摘要：Background: Graphene, a two-dimensional layer of carbon atoms forming a honeycomb crystal lattice, has attracted much attention for its extraordinary car?rier transport properties. The unique electronic structure of graphene gives rise to massless charge carriers and ballistic transport on a submicron scale at room temperature. Purpose: The tunable electrical properties realized by raising or lowering the Fermi level, allow excellent tunability of electromagnetic structures made of this material. Methods: We used terahertz time-domain analysis of the composite structure. Results: Here we demonstrate a significant amplitude modulation of THz waves with gated graphene by using extraordinary transmission through the graphene layer placed right above N-silicon substrate in the blue-violet laser of continuous irradiation. However, the reflection modulation of THz waves is weak monotonic. Conclusion: We employ the carrier transport properties of the graphene and the transport properties of the Schottky junction to analyze a graphene-silicon hybrid structure’s strange transmission reasonably.Cited  
        关键词：Graphene;Terahertz;Schottky junction;Active control   
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        发布时间：2021-03-03
      • LI Lun,WU Jinjie,GE Shuang,CHEN Fajun,WANG Peiwei,YANG Yang,LAI Wanchang
        Vol. 38, Issue 12, Article number: 120503(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120503
        摘要：Background: Air attenuation of free-air ionization chamber is one of the biggest correction terms and also has an influence on the total uncertainty of correction factor. Purpose: This study aims to measure the air attenuation correction factor for cylindrical free-air ionization chamber, and the correction of attenuation length between the diaphragm and the collecting region of cylindrical free-air ionization chamber in actual for the exact ionization current measurements. Methods: Molybdenum target X-ray vacuum tube test system and cylindrical free-air ionization chamber were used to measure the ionization current by means of vacuum. Electron Gamma Shower (EGSnrc) program was used to simulate constant pressure pipe for X-ray beam of the influence of additional losses. Results: The results showed that the ionization current of free-air ionization chamber was proportional to the pressure of the constant pressure pipe; and the extra loss of constant pressure pipe for X-ray beam was less than 0.5%; the design of the vacuum tube test system conformed to the requirements of experiment. Conclusion: For the air kerma absolute measurement of molybdenum target X-ray, the method of experimental measurement of air attenuation correction factor of cylindrical free air ionization chamber is of scientific reference value. Abstract  
        关键词：Vacuum method;Cylindrical free-air ionization chamber;EGSnrc program;Constant pressure pipe;Air attenuation;Correction factor   
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        发布时间：2021-03-03
      • TANG Xiaobin,LIU Jian,CHEN Feida,HUANG Hai,LI Huan,CHEN Da
        Vol. 38, Issue 12, Article number: 120601(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120601
        摘要：Background: It is significant to maintain the safety and reliability of nuclear engineering materials under a neutron irradiation environment. Purpose: This paper aims to investigate the irradiation damage mechanisms of CLAM, F82H and ?-Fe under the bombardment of neutrons, protons and heavy ions respectively with the aspects of material displacement damage rate and impurities deposition. Methods: The model of material damage under irradiation of reactor was established using the Monte Carlo package Geant4. Results: Irradiation damage caused by neutrons was mainly displacement damage. The distribution of displacement damage caused by protons and heavy ions corresponded to Bragg peak curve, whose incident depth and damage area were concentrated in the surface of material. 14.67-MeV protons had an incident depth of 512 ?m while 0.82-MeV 3He ions were 2.1 ?m only. Conclusion: The damage forming mechanism of metal engineering materials under extreme irradiation environment was systematically analyzed, which provided a theoretical basis for further research of material changes of macroscopic properties and microstructure after irradiation. Abstract  
        关键词：Monte Carlo method;Metal engineering materials;Displacement damage rate;Impurities deposition   
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        发布时间：2021-03-03
      • ZHU Guangyu,GAO Li,YU Fangxiaozhi,TIAN Qiwei
        Vol. 38, Issue 12, Article number: 120602(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120602
        摘要：Background: Micro-bubble Emission Boiling (MEB) is a special subcooling boiling phenomenon that the heat flux increases more highly than critical heat flux (CHF). Due to its extremely high heat transfer capability, many researchers have shown interest in it. Purpose: In this paper, we fit the heat transfer correlation of experimental data collected in visualized boiling experiments after deeply analyzing the heat transfer mechanism of MEB. Methods: Four Si-C heaters were employed for heating the copper block, which has a round heating surface with diameter of 10mm on its upper. Temperature data were measured by T-type sheathed thermocouples. The temperature of the heating surface was obtained by extrapolating the temperature distribution. Based on the heating surface temperature date in different subcoolings, least square method was used to fit Rohsenow relation to MEB. Bubble behaviors were captured by high-speed video camera with light system. Results: The experimental results showed that, when the subcooling exceeded 40 K, disturbance emerged at the liquid-vapor interface and the micro-bubble emission boiling occurred after the CHF was attained, thereafter the heat flux increased rapidly with the superheat increasing like that in typical nucleate boiling region. Based on Rohsenow relation, MEB heat transfer correlation is fitted according to the measured temperature data for heating surface of 10-mm copper in different subcoolings. The error of the relation is less than ±15%, which meets the requirement of general engineering. Conclusion: The efficient convective heat transfer of vapor-liquid replacement caused by periodic damage of the unsteady vapor film on the heating surface is the heat transfer mechanism of MEB. Abstract  
        关键词：MEB;CHF;Least squares   
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        发布时间：2021-03-03
      • LI Zhirong
        Vol. 38, Issue 12, Article number: 120603(2015) DOI: 10.11889/j.0253-3219.2015.hjs.38.120603
        摘要：Background: Currently, nuclear emergency radiation monitoring system (NERMS) contains a wide range of equipments of different performance. The operational effectiveness of NERMS can only be judged by its technical performance or through operational exercises under assumed environmental condition. However, such judgement of NERMS’s operational effectiveness can neither reflect the influence of the real environmental conditions to the NERMS, nor verify the particular contribution of different models of the same category to the operational effectiveness. While the Availability Dependability Capability (ADC) model developed by the Weapon System Effectiveness Industry Advisory Committee (WSEIAC) is widely used for quantitative evaluations of weapon systems, it is suitable only for evaluation of individual equipment rather than the whole system. And the ADC model can not reflect the influence of operational environmental conditions. Purpose: This study aims to propose a novel method for the evaluation of NERMS which is adaptable to the real operational environment. Methods: The evaluation of NERMS is divided into two parts, one is the system design capability, and the other is its adaptability to the real operational environment. The integrated evaluation index system of NERMS is constructed. And the ADC model is improved by using ‘mark’ expression. Results: The result of the evaluation can quantitatively reflect not only the total operational effectiveness of NERMS’s multiple different equipment on the same task and the contribution of NERMS’s particular equipment to the total operational effectiveness, but also the operational effectiveness of NERMS’s different equipment on different tasks. Conclusion: The model proposed in this paper may serve as a reference for developing and improving NERMS. Abstract  
        关键词：Nuclear emergency radiation monitoring;Improved ADC model;Effectiveness evaluation   
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        发布时间：2021-03-03
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