最新刊期
      卷 0 ， 期 0 ， 2020
      • ZHAO Liying YIN Chongxian LIU Dekang
        Issue 1, (2006)
        摘要：An event system distributes all timing signals to all parts of accelerator by way of broadcast. It can satisfy all requests of SSRF main timing system with clear network, high cost effectiveness, advanced technology, good isolation, easy update and expandability. In the paper, it is introduced how to complete the basic tasks of SSRF main timing system with the event system. The test proved that the jitter between main voltage and 500 MHz RF source was 31.44 ps.  
        关键词：Event system;Event generator;Event receiver;Transition board;Multimode optic fiber   
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        发布时间：2021-03-12
      • DONG Xiaohao FENG Liangjie XU Chaoyin
        Issue 1, (2006)
        摘要：Discussion on the thermal equilibrium process of the heating effect on the first crystal of a double crystal monochromator (DCM) for synchrotron radiation is presented. A testing method as well as the results of thermal effect on photon flux of U7C DCM are introduced, which is under the thermal load from a 6T single-period superconducting wiggler at NSRL. The finite element method is used to calculate the temperature distribution and thermal strain of the crystal. Both steady and transient cases with radiation cooling alone and with a combination of radiation and forced convection cooling are considered.  
        关键词：DCM;X-ray;Heat load;FEA;Beam-line;Synchrotron radiation   
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        发布时间：2021-03-12
      • CHENG Mingfu YE Bangjiao MA Weitao ZHANG Liangping HAN Rongdian WENG Huimin
        Issue 1, (2006)
        摘要：The effects of crosslinking degree, crystalline degree, branching degree of the ultraviolet-photoinitiated crosslinking polyethylene ( UPCP ) were studied by the positron annihilation lifetime spectroscopy. During the polyethylene’s crosslinking initiated by high energy radiation, I3 decreases when the crosslinking degree of polyethylene increases, but the ultraviolet-photoinitiated crosslinking polyethylene’s I3 increases when its crosslinking degree increases in our experiment, and the trend of I3 is the same as that of its crosslinking degree. This can be attributed to the fact that the increase of UPCP’s crosslinking degree makes its crystal degree decrease, and as the initiator in the photocrosslinking of polyethylene attracts the ultraviolet-photons, its polar carbonyl groups which can attract electrons strongly transform into the weakly attracting electrons’ polar hydroxyl groups.  
        关键词：Positron;Posironium;Polyethylene;Photo-crosslinking   
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        发布时间：2021-03-12
      • YIN Xinyi1,2 JIANG Shan1 HE Ming1 DONG Kejun1 ZHANG Chunhua3 ZHANG Jinsong3 ZHENG Yun3 OUYANG Yinggen4 Li Shihong1 QIU Jiuzi1,5 1
        Issue 1, (2006)
        摘要：The preparation of 182Hf standard samples for AMS measurement is presented. It consists of four processes, including synthesis of radioactive nuclides, accurate measurement of isotopic ratios, dilution of standards and preparation of HfF4. So far we have measured the initial isotopic ratio of 182Hf/180Hf with TIMS, the result is (2.33±0.07)×10-6. We have prepared a series of standards with different isotopic ratios (10-6—10-13) and given the uncertainty of the standards.  
        关键词：182Hf;Accelerator mass spectrometry (AMS);Standard samples;Thermal ionization mass spectrometry (TIMS);Isobar   
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        发布时间：2021-03-12
      • YU Xuefeng AI Erken REN Diyuan GUO Qi ZHANG Guoqiang LU Wu
        Issue 1, (2006)
        摘要：By hot-carrier injecting and room temperature annealing repeatedly, responses of the MOS structure to the hot-carrier injection and annealing characteristics have been studied using the technique of c-v analyses. The mechanism of hot-carrier injection induced damage in the MOS structure has also been investigated in view of generation and annealing of the interface states.  
        关键词：Hot-carrier;Interface states;Irradiation;Annealing   
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        发布时间：2021-03-12
      • CHEN Chaobin HUANG Qunying WU Yican LIN Hui
        Issue 1, (2006)
        摘要：Application of Monte Carlo techniques in radiation treatment planning is described in the paper. The Monte Carlo code BEAM is used to model Varian Clinic 6 MV X-ray treatment head and also a CT based HEAD phantom is simulated with DOSXYZ code using the BEAM output phase space data as the incident radiation source. Results of the simulations are presented, and compared with the Off-Axis Ratio (OAR) based method with tissue-air ratio algorithm for inhomogeneity corrections in photon beam dose calculations. The isodose lines and the cumulative dose-volume histogram of the TARGET in the two kinds of methods are in good accordance, with just slight deviation in some regions. In addition, the method of how to build a Monte Carlo geometry from the CT images of a patient is discussed in the paper.  
        关键词：Radiation treatment planning;Monte Carlo techniques;CT image;Dose calculation;the Advanced/Accurate RadioTherapy System (ARTS )   
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        发布时间：2021-03-12
      • CHEN Ning1,2 SUN Xudong1,3 JI Genzhong1,3 ZENG Minfeng1 ZHENG Houtian1,3 XU Jincheng2 QI Chenze1 1
        Issue 1, (2006)
        摘要：By means of positron annihilation lifetime spectroscopy (PALS), the compatibility of polystyrene (PS) / polyvinyl acetate (PVAc) and PS / polymethyl methacrylate (PMMA) blend systems have been studied. The results show that both PS/ PVAc and PS/PMMA blends are immiscible, but the miscibility between PS and PVAc is better than that between PS and PMMA.  
        关键词：Positron annihilation lifetime spectra (PALS);Polystyrene;Polyvinyl acetate;Polymethyl methacrylate;Miscibility   
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        发布时间：2021-03-12
      • CHEN Zhenping1 LI Xigui2 SU Yuling1 XUE Yuncai1 LIU Haizeng1 GONG Shicheng1 ZHAO Jingxun1 1
        Issue 1, (2006)
        摘要：To make clear the influence of magnetic rare-earth ion Gd3+ doping in the Y site on crystal structure and localized electron structure of YBCO system, the Gd-doped Y1-xGdxBa2Cu3O7-δ (x=0—1.0) systems were studied systematically by the positron annihilation technique and X-ray diffraction (XRD). The XRD analysis reveals that Gd3+ with bigger radius doping in Y site makes the crystal parameters and crystal volume increase, while all the samples remain the single orthorhombic phase as YBa2Cu3O7-δ (YBCO) system does. The temperature dependence of resistance measurement shows that Tc is above 90 K for all samples, and Tc increases with increasing Gd3+ content. The positron experiment indicates that the localized electronic density ne decreases with increasing Gd3+ content.  
        关键词：Positron annihilation;Crystal structure;Superconductivity;Localized electron density   
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        发布时间：2021-03-12
      • YAO Kai1,2 ZHANG Jincang1 LI Lingwei1 CAO Guixin1 JING Chao1 CAO Shixun1 1
        Issue 1, (2006)
        摘要：The La5/8Ca3/8Mn1-xCoxO3 (0≤x≤0.3) has been systematically studied by means of positron annihilation technique and X-ray diffraction method together with the transport properties measurement. The results show that all the samples have orthorhombic pervoskite structure, and with the increase of Co doping concentration x, the peak value of resistivity ρp increases quickly, and the corresponding metal-insulator transition temperature Tp decreases. The positron annihilation parameters τ1, τ2 and I2 show strong x dependence. The shorter lifetime τ1 and longer lifetime τ2 show a decreasing trend with the increase of x in totally, while the longer lifetime intensity I2 shows an increasing trend. The local electron density ne calculated from positron lifetime parameters has an increasing trend with the increase of x. Together with the transport properties, it could be confirmed that with the increase of Co doping concentration the electron localization effect is strengthened gradually. The Co doping at Mn site causes the conduction network of Mn3+ – O – Mn4+ partly destroyed. It also enhances the electron – phonon coupling effect, then causes the number of itinerant electrons to decrease and the number of electrons in localized state to increase.  
        关键词：Positron annihilation;Electron localization effect;Transport properties   
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        发布时间：2021-03-12
      • QI Yongqing1,2 ZHANG Xinbao1 HE Xiubin1 WEN Anbang1 FU Jiexiong1,2 1
        Issue 1, (2006)
        摘要：Acquiring the 137Cs reference inventory values is the first step for using 137Cs technique to estimate rates of soil erosion and sediment deposition. The 137Cs reference inventories distribution in China is calculated in this paper by using the model and software of the fallout 137Cs reference inventory, which is established by Walling and He. The modeling results are compared with the measured 137Cs reference inventories in China, and then some defects of the Walling and He’s model of the fallout 137Cs reference inventory are indicated. In this paper, the 137Cs reference inventories distribution pattern of China and the major influence factors are analyzed too.  
        关键词：137Cs reference inventory;Distribution pattern;China   
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        发布时间：2021-03-12
      • WANG Yanli1 BAO Borong1 WU Minghong2 JIAO Zheng2 GU Jianzhong2 1
        Issue 1, (2006)
        摘要：Dichlorobenzenes are a kind of organic contaminations which are usually difficult to be decomposed by normal methods. Decomposition of O-, M-, P-dichlorobenzenes by electron beam (1 mA, 1.5 MeV) irradiation was studied in this paper. The irradiation doses of electron beam are 35 kGy, 70 kGy, 105 kGy, 140 kGy, 210 kGy, respectively. The results show that dichlorobenzenes can be decomposed efficiently with electron beam, the needed doses are 38 kGy, 35 kGy, 46 kGy, respectively, for O-, M-, P-dichlorobenzene with a degrading rate of 50%. The mass concentration of chlorine ion increased during irradiation and pH of irradiated solution was at the range of 2—3. Mechanism of dichlorobenzene decomposition is discussed in the paper according to the results of experiment.  
        关键词：Electron beam;Decomposition;Dichlorobenzene   
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        发布时间：2021-03-12
      • LIN Yansong1 DING Shiyu2 CHEN Zhengping2 WANG Bocheng1 ZHANG Manda2 WANG Shizhen1 1
        Issue 1, (2006)
        摘要：The experiment was designed to investigate the variation of DAT and D2 receptor in morphine administered and 1,2,3 day abstinent rats. Morphine exposure was induced by repeated morphine (i.p.) treatment for 8 days. Conditioned place preference test was conducted to evaluate the drug seeking behaviour and morphine dependence of rats with morphine exposure. Biodistribution of the imaging agents 125I-β-CIT and 125I-IBZM was used to evaluate the central DAT and D2 receptor during morphine exposure and 1,2,3 day’s abstinence. Results reveal the following facts. (1) The morphine abstinent rats showed diarrhea and body-shake 1 day after morphine withdrawal. (2) For morphine group, 125I-β-CIT %ID/g in ST and NAC was higher than that of the 1,2,3 day’s abstinent rats and control (P<0.05). No difference was found between 1,2,3 day’s abstinent group and control group (P>0.05). (3) 125I-IBZM %ID/g in ST, NAC and HIP in morphine rats were lower than those of the abstinent and control rats (P<0.05). The 125I-IBZM %ID/g in ST and NAC gradually increased with the abstinent days. While in ST the %ID/g among the abstinent rats was all lower than that of the control rats, in NAC the %ID/g was still lower in 1 day’s abstinent rats (P<0.05), and no difference in 2 and 3 day’s abstinent rats was observed in comparison with the control (P>0.05), indicating the reduction of hyper-activated DAT and the increase of down-regulatory D2 receptor induced by morphine during morphine withdrawal. Our results confirmed that the dopamine system, especially DAT and D2 receptor in mesolimbic and meso-striatum pathway, has been implicated in morphine treatment. The rewarding properties of morphine and the somatic expression of morphine abstinence were related to changes in mesolimbic and meso-striatum dopaminergic activity.  
        关键词：Drug dependence;Morphine;Dopamine transporter;D2 receptor;125I-B-CIT;125I-IBZM   
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        发布时间：2021-03-12
      • TANG Ganghua1 TANG Xiaolan2 WANG Mingfang1 LUO Lei1 GAN Manquan1 1
        Issue 1, (2006)
        摘要：To improve the automated synthesis technology of 18F-fluoroacetate (18F-FAC) as tumor imaging agent, the one-pot procedure at TRACERlab FXF-N module was tried. 18F-FAC injection was obtained via a two-step reaction including nucleophilic fluorination of the precursor benzyl bromoacetate with 18F-fluoride and subsequent hydrolysis of the protecting group with 3 mol/L NaOH at the same reaction vessel, and purification with HPLC system. 18F-FAC was automatically synthesized with an uncorrected radiochemical yield of more than 45% and radiochemical purity of more than 99% in the synthesis process of about 50 min. 18F-FAC injection is easy to be obtained and can be used for clinical and scientific study with positron emission tomography (PET) imaging.  
        关键词：18F-fluoroacetate;Tumor imaging agent;Automated synthesis   
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        发布时间：2021-03-12
      • WANG Mingwei YIN Duanzhi WANG Yongxian
        Issue 1, (2006)
        摘要：The positron-emitting nuclide fluorine-18 is of great importance to modern nuclear medicine with the increasing clinic demands of positron emission tomography (PET) and R&D of PET radiopharmaceuticals worldwide. Fluorine-18 can be introduced into a target molecule to prepare the corresponding 18F-labeled radiopharmaceuticals through direct and indirect radiofluorinations. However, it is not suitable for the preparation of biomacromolecular-oriented radiopharmaceuticals such as peptides and protein using the direct labeling methods because of the lack of reaction selectivity. Thus, it is necessary to choose an appropriate 18F-labeled intermediate for the indirect labeling methods. According to the classification of precursors displaced by 18F, this paper briefly introduces two species of 18F-labeled intermediates originated from aliphatic and aromatic displacements and their syntheses and applications in PET radiopharmaceutical domain.  
        关键词：Fluorine-18;Nucleophilic radiofluorination;Labeled intermediates   
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        发布时间：2021-03-12
      • LIU Shubin GUO Jianhua ZHANG Yanli ZHAO Long AN Qi
        Issue 1, (2006)
        摘要：In the high energy physics domain there is a trend to use integrated, high resolution, multi-hit time-digital-converter for time measurement, of which the data driven TDC is an important direction. Study on the method of how to test high performance TDC’s characters and how to improve these characters will help us to select the proper TDC. We have studied the testing of a new high resolution TDC, which is planned to use in the third modification project of Beijing Spectrometer (BESIII). This paper introduces the test platform we built for the TDC, and the method by which we tested for nonlinearity, resolution, double pulse resolution characters, etc. The paper also gives the test results and introduces the compensation way to achieve a very high resolution (24.4 ps).  
        关键词：HPTDC;Effective resolution;Code density test;Nonlinearity;Cable delay measurement test;Compensation   
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        发布时间：2021-03-12
      • WANG Chongjie1 ZHANG Ailian2 Lü Jianzhou3 1
        Issue 1, (2006)
        摘要：A kind of efficiency function of HPGe γ detector with respect to the point radioactive sources and the method of determining its parameters are brought forward. By means of the function and numerical method, 226Ra, 232Th and 40K in two standard samples are analyzed, and the results are coincident with the known parameters, so the applicability of the function and the method is proved. In principle, this nondestructive analytical method can be applied to samples with any shapes.  
        关键词：HPGe γ detector;Detecting efficiency;Point radioactive source;Total-energy peak;γ spectrum analysis   
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        发布时间：2021-03-12
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