最新刊期
      卷 0 ， 期 0 ， 2020
      • CHENG Lin SONG Li MA Chuntao LUO Hongxin WANG Jie
        Vol. 33, Issue 7, (2010)
        摘要：The beamlines slits of Shanghai Synchrotron Radiation Facility(SSRF) are required to have a repeatability of better than 1 μm.Before the slits installation,the off-line and/or on-line repeatability measurements must be conducted.A machine vision measuring system based on high resolution CCD and adjustable high magnification lens was used in this regard.A multi-level filtering method was used to treat the imaging data.After image binarization,the imaging noises were depressed effectively by using of algebraic mean filtering,statistics median filtering,and the least square filtering.Using the subtracted image between the images before and after slit movement,an average displacement of slit blades could be obtained,and the repeatability of slit could be measured,with a resolution of 0.3 μm of the measurement system.The experimental results show that this measurement system meets the requirements for non-contact measurements to the repeatability of slits.  
        关键词：Precision slits;Repeatability;Micro-imaging;In-plane displacement   
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        发布时间：2021-03-05
      • LUO Xiaowei1,2 XIANG Xinlei1 XIE Jialin11
        Vol. 33, Issue 7, (2010)
        摘要：A new design of electron linac is developed at Institute of High Energy Physics,Chinese Academy of Sciences.It adopts the spent beam of a high power klystron as the electron source,hence the elimination of an electron gun,and simplified structure of the linac.The test results of the prototype linac,however,showed that the output beam intensity was much less than the design specification.Efforts to improve the prototype linac have been made.The Parmela code calculation shows a new design that reduces the beam loss.The simulated beam current output reaches 100 mA,which suggests feasibility of the scenario.  
        关键词：Linac;Klystron;Performance;Beam loss   
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        发布时间：2021-03-05
      • GONG Jie1 LI Chaoli1 WANG Wei1 LU Liyan1 LI Shizhuo2 HE Ming1 JIANG Shan1 1
        Vol. 33, Issue 7, (2010)
        摘要：32Si,the only long-life(~140 a) radioisotope of silicon,plays a unique role in geochronometry in the range of 100-1000 years,and in research of the global biogeochemical silica cycle.Because of its ultra high sensitivity,minute sample amount and short measurement time,the accelerator mass spectrometry(AMS) is the most proper method for detecting 32Si.China Institute of Atomic Energy has been making efforts in establishing the ultra-sensitive method of 32Si determination via AMS.31P and 30Si targets are irradiated in a swimming pool reactor to produce 32Si.Chemical procedures to extract the 32Si from the irradiated targets have been decided,along with electric conductor materials and the mixing ratio,the negative ion formation method,and processes to dilute the solutions to form high 32Si abundance samples.After several tests and improvements of the experimental conditionals,we were able to measure the sample at the abundance of 10-13 in a sensitivity of better than 1.5×10-14.In this paper,we report our progresses in establishing the AMS-based ΔE-Q3D method for 32Si determination.  
        关键词：32Si;Accelerator mass spectrometry;ΔE-Q3D;Irradiation;Ultra-sensitive measurement   
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        发布时间：2021-03-05
      • YANG Kang1,2 CHEN Xiliang1,2 MA Mingwang1,2 YANG Shumin1,2 CAO Jianqing1 WANG Yongqi1 ZHU Zhiyong1 1
        Vol. 33, Issue 7, (2010)
        摘要：In this work,performances of terahertz emitters made of semi-insulating GaAs(SI-GaAs) was improved by 1.5 MeV He+ ion implantation.The time-domain signal strength of the implanted SI-GaAs is about three times higher than that of the non-irradiated sample.The photoconductive antenna(PCA) on a substrate of He+-implanted SI-GaAs possesses slightly higher time-domain signal strength and slightly broader frequency range than those of the PCA on an LT-GaAs substrate,with similar signal-to-noise ratio.The best THz wave emission property can be achieved by implanting the SI-GaAs with 1.5 MeV He+ ions of about 1×1016 cm-2 at room temperature.  
        关键词：Ion implantation;THz spectra;Photoconductive antenna   
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        发布时间：2021-03-05
      • DIAO Lijun1 HOU Tiedong2 LI Wei1 MENG Jun1 1
        Vol. 33, Issue 7, (2010)
        摘要：Based on material shielding,a newly developed anti-cosmic low-background γ-ray spectrometer is used to conduct experimental study on background reduction of secondary cosmic muons and neutrons by combining anticoincidence shielding with thermal neutron shielding.The results show that the anticoincidence shielding(plastic scintillation detector) can reduce the μ background significantly on the HPGe detector,while effectively suppressing the background from the fast neutron inelastic scattering on the Ge crystal and shielding materials.The suppression factor of the anticoincidence integrated background is up to 8 in the energy region of 100-2000 keV.The addition of thermal neutron shielding(Cd absorber) can obviously reduce the background generated by the thermal neutron captured in the Ge and shielding materials,increasing the suppression factor of 511 keV γ-ray annihilation peak background from 5.8 to 20.7,and the suppression factor of anticoincidence integrated background in 100-2000 keV to 13.2.  
        关键词：Anticoincidence;Thermal neutron;Low background;Cosmic-ray;γ spectrometer   
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        发布时间：2021-03-05
      • ZHANG Changfan GONG Jian LIU Suping HU Guangchun XIANG Yongchun
        Vol. 33, Issue 7, (2010)
        摘要：Template measurement is of importance in deep nuclear disarmament.The γ-ray spectrum of plutonium pit shows unique property due to age,isotopic abundance and mass of the plutonium pit.The pits of the same design have similar γ-ray spectra,but the spectrum differs form that of a pit in different design.Useful information can be extracted from γ-ray spectrum generated by using a standard plutonium pit as a template.A comparison between the inspected objects and the template leads to conclusion whether they are of the same type.In this paper,we study how to choose the template data from γ-ray spectrum and discuss limitations of using the γ-ray spectrum only.Because of strong self-absorption of plutonium,some characteristics of plutonium pit cannot be identified by the gamma spectrum only.MCNP simulations were employed to prove that,in some cases,template depending on just the γ-ray spectrum cannot effectively distinguish the spurious objects.And a further approach indicates that enhancing neutron counting rate of spontaneous fission of plutonium can improve the model identification.  
        关键词：Plutonium pit;Template measurement;γ spectrum;Neutron count rate   
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        发布时间：2021-03-05
      • WU Hexi1,2 LIU Qingcheng1,2 YANG Bo2 LIU Yujuan2 1
        Vol. 33, Issue 7, (2010)
        摘要：Sensitive nonlinear iterative peak algorithms were discussed and applied to analyze the background of full-energy spectra of the γ-ray in this article.Under high-order filtering or at narrow windows,SNIP algorithms can restrain the influence of Compton scattering greatly and decrease the background effect of backscattering peaks,background peaks and characteristic X-rays from the shielding material,but this reduces full-energy peak counts.On the other hand,the full-energy peak counts become larger than the actual value using low-order filtering or at wide windows.By analyzing the conditions of SNIP algorithms,one can locate the boundary of peaks accurately.High analytical accuracy of specific activity of natural radionuclides can be achieved by SNIP algorithms with the filtering window changing in a large scale.The total relative error for measuring natural radionuclide specific activity of 238U,232Th and 40K is less than 8.5% using the fourth-order filtering at the window varying between 47 and 123.  
        关键词：SNIP Algorithms;Restrain background;Full-energy spectra   
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        发布时间：2021-03-05
      • CHEN Song TANG Yu WANG Xuanli HANG Yanling HUANG Yuyang DENG Wen
        Vol. 33, Issue 7, (2010)
        摘要：The measurements of XRD,thermoelectric properties,positron lifetime and its coincidence Doppler broadening spectra for the samples of CuAl1-xFexO2(0≤x≤0.20) were performed.The results show that doping the CuAlO2 with small amount of Fe(x≤0.10) enhances the 3d electron signals of positron coincidence Doppler broadening spectra of the sample,and reduces the S parameter and mean lifetime of the positrons,and resistivity of the sample as well,whereas for x>0.10,the S parameter,and lifetime of positron,and the sample resistivity,increase with the Fe contents,but the 3d electron signal decreases with increasing Fe contents.The Seebeck coefficients of CuAl1-xFexO2 at room temperature increase with defect concentration.The Fe dopant effects on microstructure and thermoelectric properties of CuAlO2 are discussed.  
        关键词：Thermoelectric property of CuAlO2;3d electron;Microdefect;Positron annihilation   
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        发布时间：2021-03-05
      • CHEN Yanzhou SUN Guangai HUANG Chaoqiang CHEN Bo
        Vol. 33, Issue 7, (2010)
        摘要：In order to satisfy both high flux and high resolution of residual stress neutron diffractometer,the monochromator was simulated using Monte Carlo simulation code SIMRES.A series of factors,including the diffraction geometries(symmetric diffraction,asymmetric diffraction and fully asymmetric diffraction),focusing conditions(vertical and horizontal focusing curvatures) and crystal types(perfect crystal and mosaic crystal),were considered in the simulation to study,taking the figure of merit(FoM) as a comparison measure,the influences of flux on resolution of the diffractometer.The results show that use of symmetric diffraction and perfect crystal double focusing could achieve the best performance.  
        关键词：Monte Carlo simulation;Residual stress neutron diffractometer;Focusing monochromator;SIMRES   
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        发布时间：2021-03-05
      • WANG Yunbo LI Gongping LI Tianjing GAO Xingxin
        Vol. 33, Issue 7, (2010)
        摘要：Co-doped ZnO and as-grown ZnO single crystals were irradiated by 2.5 MeV neutrons from D-D reaction on a neutron generator,and the structural and optical properties were investigated by X-ray diffraction(XRD),photoluminescence(PL) and optical transmittance at room temperature.The results indicated that a great number of defects of oxygen vacancies(VO) and antisite oxygen(OZn) were introduced in the as-grown ZnO,and a few defects of interstitial zinc(Zni) and interstitial oxygen(Oi) were introduced after irradiation.The nanoclusters of metallic cobalt and cobalt oxides in the Co-doped ZnO disappeared after the neutron irradiation,and a great many Co2+ ions substituted for Zn2+ ions moved away probably from the lattice site due to the fast-neutron collision.The defects of interstitial cobalt impurities and zinc vacancies(VZn) were formed in the Co-doped ZnO irradiated by fast neutrons.The fast-neutron-irradiated samples are still of wurtzite structure and in c-axis orientation.This work shows that ZnO and Co-doped ZnO semiconductors have great radiation hardness,hence their potential of space applications,and the findings are of help in studying point defects of ZnO.  
        关键词：ZnO single-crystal;Co-doped ZnO;Fast-neutron irradiation;Defect   
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        发布时间：2021-03-05
      • WEI Xiye YUAN Yonggang
        Vol. 33, Issue 7, (2010)
        摘要：Multisphere neutron spectrometer is widely used for measuring neutron spectrum duo to its advantages of functional simplicity,wide energy domain,isotropic response and high sensitivity.In this work,the response function of multisphere neutron spectrometer was simulated by using the MCNP code,and the results agree well with those obtained by Vega-Carrillo et al.Meanwhile,response results of the multisphere spectrometer we designed referring to existing systems and practical requirements are discussed with different reaction channels and the S(α,β) scattering treatment.Thus,the response characteristics of the BSS are obtained under different boundary conditions.  
          
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        发布时间：2021-03-05
      • GUO Hongxia WANG Wei LUO Yinhong ZHAO Wen GUO Xiaoqiang ZHANG Keying
        Vol. 33, Issue 7, (2010)
        摘要：SEE have became a substantial Achilles heel for the reliability of space-based advanced CMOS technologies with features size downscaling.Future space and defense systems require identification and understanding of single event effects to develop hardening approaches for advanced technologies,including changes in device geometry and materials affect energy deposition,charge collection,circuit upset,parametric degradation devices.Topics covered include the impact of technology scaling on radiation response,including single event transients in high speed digital circuits,evidence for single event effects caused by proton direct ionization,and the impact for SEU induced by particle energy effects and indirect ionization.The single event effects in CMOS replacement technologies are introduced briefly.  
        关键词：SET;SER;SEFI   
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        发布时间：2021-03-05
      • LAN Bo1,2 GUO Qi1 SUN Jing1 CUI Jiangwei1,2 LI Maoshun1,2 FEI Wuxiong1,2 CHEN Rui1,2 ZHAO Yun1,2 1
        Vol. 33, Issue 7, (2010)
        摘要：The total-dose response and annealing effect of p-channel metal oxide semiconductor field-effect transistors(PMOSFETs) of different types,i.e.HCF4007UB of ST,Italy;CC4007B,a homemade transistor in China,and 3SJ11A,2SJ196 and 2SJ178 of NEC,Japan;were investigated at different dose rates and bias conditions.The results show that the shift of threshold voltage increases with the total-dose.Under various conditions,different dose-rate effects(time-dependent effect and enhanced low-dose-rate sensitivity) can be observed for the types of devices.So the radiation-induced ELDRS in the PMOSFETs is not a universal phenomenon.  
        关键词：PMOSFETs;Bias;Dose rate;Time-dependent effect;Enhanced low-dose-rate sensitivity   
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        发布时间：2021-03-05
      • SU Tingting1 YANG Tingting1 JI Guohong1 XIANG Xingjia1 CHEN Xuetao1 WANG Yu1 WU Yaojin2 1
        Vol. 33, Issue 7, (2010)
        摘要：The germinability and gemination rate of Stevia rebaudianum seeds implanted with 20 keV N+ ions in doses of 0(CK),100×2500,400×2500 and 1000×2500 N+/cm2 were studied by analyzing the differences in seed germinability and gemination rate between the groups.By statistical analysis,the germinability and gemination rate were affected at the level of α=0.05 by the implantation dose.The results showed that the germinability and gemination rate increased with the dose first and then decreased.At 400×2500 N+/cm2,the seeds had the largest germinability and the gemination rate.  
        关键词：Stevia;Ion beam;Germinability;The rate of germination   
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        发布时间：2021-03-05
      • YANG Cuiyun1 WENG Jiaqiang2 LIU Haiying1 1
        Vol. 33, Issue 7, (2010)
        摘要：The Kapchinsky-Vladimirsky(K-V) beam propagation through a periodic focusing channel is studied using the particle-in-cell(PIC) code and the logarithm-function controller.The results show that the radial ion density is uniform and the ion density distribution has nothing to do with any region where the controlling information comes from.This provides a reference for detector and target material deployments in experimenting with high intensity ion beams.  
        关键词：Halo;The logarithm-function controller;Radial density;Information regions   
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        发布时间：2021-03-05
      • ZHANG Songbai1 WU Jun1 XIE Dong1 TIAN Dongfeng2 1
        Vol. 33, Issue 7, (2010)
        摘要：The MLEM(Maximum Likelihood-Expectation Maximization) algorithm is used to reconstruct the distribution of source based on the principle of MURA(Modified Uniformly Redundant Array) coded aperture imaging.Through numerical analyzing,the distribution of single energy 413 keV,a plane-source on the image plane is obtained.The reconstruction result by the MLEM algorithm agrees with the original distribution.Then,through the simulation of coded aperture image for the hypothetical Pu component by MCNP,and the image reconstruction of the source,the method based on coded aperture imaging to measure the symmetry attribution of plutonium component is validated.The numerical simulation result shows that coded aperture imaging is more advantage than pinhole imaging to measure the symmetry of Pu component in the fields of detection efficiency of gamma ray and protection of sensitive information.  
        关键词：Coded Aperture;MURA;MLEM;Symmetry attribution of plutonium component   
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        发布时间：2021-03-05
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