最新刊期
      卷 0 ， 期 0 ， 2020
      • YU Haibo1,3 LIU Jianfei 1,3 HOU Hongtao 1,3 MA Zhenyu 1,3 FENG Ziqiang 1,3 MAO Dongqing1
        Vol. 35, Issue 1, (2012)
        摘要：Adopting a higher harmonic cavity on a synchrotron radiation facility can increase the beam lifetime and suppress the beam instability.In this paper,we report the simulation and preliminary design on higher order modes(HOMs) damping of the designed and fabricated higher harmonic superconducting cavity for Shanghai Synchrotron Radiation Facility(SSRF).The requirements for the HOM damping are analyzed,and the length and location of the HOM damper are optimized by using the SEAFISH code.The results show that the design can provide heavy damping for harmful HOMs with decreased impedance,and the beam instability requirement of SSRF can be satisfied.By using the ABCI code,the loss factor is obtained and the HOM power is estimated.  
        关键词：Higher harmonic superconducting cavity;Higher order modes damping;Simulation;Loss factor   
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        发布时间：2021-03-05
      • WANG Qisheng1,2 HUANG Sheng1 SUN bo1 TANG Lin1 HE Jianhua1 1
        Vol. 35, Issue 1, (2012)
        摘要：The macromolecular crystallography beamline BL17U1 of Shanghai Synchrotron Radiation Facility (SSRF) is an important platform for structure biological science.High performance of the beamline would benefit the users greatly in their experiment and data acquisition.To take full advantage of the state-of-the-art mechanical and physical design of the beamline,we have made a series of efforts to develop a robust control and data acquisition system,with user-friendly GUI.These were done by adopting EPICS and Blu-Ice systems on the BL17U1 beamline,with considerations on easy accommodation of new beeline components.In this paper,we report the integration of EPICS and Blu-Ice systems.By using the EPICS gateway interface and several new DHS,Blu-Ice was successfully established for the BL17U1 beamline.As a result,the experiment control and data acquisition system is reliable and functional for users.  
        关键词：Data acquisition;EPICS;Blu-Ice;EPICS gateway   
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        发布时间：2021-03-05
      • DI Lanlan GU Ming YUAN Qibing FAN Xuerong
        Vol. 35, Issue 1, (2012)
        摘要：A trigger pulse delay and assignation apparatus,using an appropriative and controllable delay line chip,has been developed for SSRF storage ring injection system.With the input being one light pulse,and the outputs being 4 electric pulses,the delay is independent and adjustable,and the rise time is short and jitter is low.The delay is 0.25-ns steps,with an adjustable range of up to 64 ns.In addition to the function of pulse delay,the apparatus also has the interlock function and LCD display.It can be operated on keyboard,and can be controlled remotely through its serial port.  
        关键词：Subnanosecond;Delay and assignation apparatus   
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        发布时间：2021-03-05
      • LI Hang 1 WEN Weiwei1 WANG Sheng1 ZOU Yubin1 GUO Zhiyu1 TANG Guoyou1 LU Yuanrong1 WU Shiping2 YANG Fen2 1
        Vol. 35, Issue 1, (2012)
        摘要：Detection of residual aluminum-base core in nickel alloy is important for manufacturing blades of an aero-engine.Because of the strong penetrability,neutrons are more effective than X-rays to detect residual material in the nickel alloy blade.In this paper,both theoretical calculation and experiments on an accelerator-based neutron source at Peking University are used to verify the feasibility of Gd-tagging neutron radiography in detecting residual aluminum-base core in the nickel alloy.The results show that the technique can achieve a sensitivity of 0.2 mg for the residual core detection.  
        关键词：Neutron radiography;Gd-tagging;Aero-engine blades;Residual aluminum-base core   
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        发布时间：2021-03-05
      • ZHANG Lu1 HE Chaohui1 CHEN Liang2 ZHANG Zhongbing2 LIU Jinliang2 REN Xiaotang3 1
        Vol. 35, Issue 1, (2012)
        摘要：In proton single-event-effects experiments,and proton accelerators for advanced researches,precise measurement of proton beam current is important for reliability and accuracy of the experiments.Traditional detection methods,such as Faraday cup,Si(Au) surface barrier detector,and diamond detector,are of beam-block type measurements,where changes in proton beam current can hardly be monitored in-site.In this paper,film scintillators are used to detect the proton beam.Protons travel through the film scintillator,deposit part of the energy and make the scintillator emit lights,which are collected by a photomultiplier tube.Rresponse of the film scintillator to protons are calculated and verified by experiments with proton beams at 3–10 MeV from the 2×6 MeV tandem accelerator at Peking University.  
        关键词：Thin film scintillator;Relative light output;Energy deposition;Proton beam intensity   
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        发布时间：2021-03-05
      • WU Yang TANG Bin HUO Heyong LIU Bin TANG Ke SUN Yong YIN Wei CAO Chao
        Vol. 35, Issue 1, (2012)
        摘要：In this work,a mathematical model was established to estimate luminescence of the neutron radiography scintillator made of ZnS and polypropylene.Scintillators in different thicknesses and compositions were prepared for a radiography experiment using 14 MeV neutrons.The results showed that the optimum parameters of the scintillator were 3-mm in thickness and 1:1 to 2:1 of weight ratio of ZnS and polypropylene.  
        关键词：Neutron scintillator;Luminescent properties   
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        发布时间：2021-03-05
      • YANG Yiwei 1,2 YANG Yigang 1
        Vol. 35, Issue 1, (2012)
        摘要：To improve imaging performance of photo-neutron explosive detection system,reasons of spatial resolution deterioration is investigated,and physical and mathematical model are established.The function is solved using iterative algorithm under constraints and non-constraints condition,respectively.The simulation and experiment results show that the method with constraints can improve effectively accuracy of the explosives detection system by eliminating the pixel overlapping.  
        关键词：Neutron image;Iterative algorithm   
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        发布时间：2021-03-05
      • PAN Xiaobing1 QUAN Lin1 YU Xiaoren1 QU Guangwei2 WANG Shaoshun2 1
        Vol. 35, Issue 1, (2012)
        摘要：For 137Cs monitoring in environmental water samples,a NaI(Tl) system consisting the detector and a lead chamber containing Cs solution of different concentrations was used for Monte Carlo simulation and experimental calibration on γ-ray spectrum response of the NaI(Tl) detector.The spectrum response of a point source was simulated.The detector was placed in an SS glove and immerged in the 137Cs solution.The results show that the MC model verified by high specific activities can be used to calibrate the detector system for environmental water samples of low activity levels.This method provides technical support for online monitoring of 137Cs.  
          
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        发布时间：2021-03-05
      • GUO Huiping WANG Hongchao XU Zhilin ZHANG Lei
        Vol. 35, Issue 1, (2012)
        摘要：This work was aimed at developing a solid track spark counter.The structure and parameters were optimized via experiments.The spark counter can read the solid track information on polyester film more accurately.It can be applied to radon measurement.  
        关键词：Polyester-film;Spark counter   
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        发布时间：2021-03-05
      • ZHU Jinhui HUANG Liuxing NIU Shengli
        Vol. 35, Issue 1, (2012)
        摘要：In this work,the neutron transport in a supercritical system was simulated by an MC code.The multiplication factor and prompt removal lifetime were obtained,which agreed well with the MCNP results.The multiplication time constant of the supercritical system was studied numerically by using the time station module.The relationship between multiplication time constant and multiplication factor for a supercritical system was investigated.The results indicate that the multiplication time constant is not only related to the multiplication factor keff,but also affected by the mean time of fission.  
        关键词：Supercritical system;Multiplication factor;Multiplication time constant;Mean time of fission   
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        发布时间：2021-03-05
      • ZHANG Junyuan1 CHEN Feng2 SUN Weizhong1 Lü Xiaodang2 HE Pingni Gou Fujun 1,3 1
        Vol. 35, Issue 1, (2012)
        摘要：In this paper,the one-dimensional particle-in-cell/Monte Carlo collision model is used to simulate time evolution of the Ar discharges produced by a single-frequency capacitively coupled reactor,by considering the elastic and inelastic collisions between Ar,Ar+,Ar* and electrons.The results show that the sheath near the powered electrode is formed in a short time and thickness of the sheath increases with the simulation time,while fluxes of the electrons and Ar+ ions at the powered electrode decrease with increasing time.The flux,potential,current and sheath thickness reach their equilibrium in a few hundred microseconds.The plasma density,potential,electric field and averaged energy are discussed.  
        关键词：Plasma;Sheath;Particle-in-cell/Monte Carlo collision;Capacitively coupled reactor   
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        发布时间：2021-03-05
      • YANG Lei1 LIU Yujuan2 WU Hexi2 WANG Ling2 1
        Vol. 35, Issue 1, (2012)
        摘要：A practical small-scale PC cluster based on Windows OS for MCNP5 parallel computation was constructed.As an example,the response of GM detector to γ-ray energy was calculated by the PC cluster and some other computers.The results show that performance of the PC cluster was nearly 5 times more than that of a single CPU computer of similar investment.The PC cluster is simple,and its management in batch mode is easy and flexible.It shall be a practical solution for the users who request a handsome computing power.  
          
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        发布时间：2021-03-05
      • DONG Xiaoxia WANG Mengdie HU Guangshu ZHANG Hui
        Vol. 35, Issue 1, (2012)
        摘要：In this work,we used the GATE code to simulate a dual-head positron emission mammography(PEM) system using LYSO detectors and evaluate its performances.The NEMA NU 4-2008 standard,modified slightly,was referred for the PEM system.System performances of sensitivity,phantom scattering,crystal scattering,counting rate and intrinsic spatial resolution were simulated.A peak absolute sensitivity of 14.17%,intrinsic spatial resolution of 1.2 mm and the peak NEC rate of 1.508×105/s at an activity of 29.6 MBq in a breast phantom were found at a 350–650 keV energy window and 6 cm detector separation,meeting the system needs.  
        关键词：Breast cancer;dual-head PEM;Monte Carlo simulation;GATE   
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        发布时间：2021-03-05
      • FENG Guanghua ZUO Guoping GONG Xueyu KANG Xi
        Vol. 35, Issue 1, (2012)
        摘要：Carbon-9 ion beam is a source with dual radiations.Compared with other heavy ions,9C ion beam has an obvious advantage in the treatment of cancer.In this paper,we perform a Monte Carlo simulation of 290 MeV/u 9C ion beam transport in water with the FLUKA code.The energy deposition,dose,distribution and fluence of nuclear fragments along the penetration depths of the 9C ions are obtained.The results are useful for dosimetry of malignant tumors treatment with 9C ion beam.  
        关键词：9C ions beams;Nuclear fragmentation;Bragg peak;Energy deposition   
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        发布时间：2021-03-05
      • NING Shasha SHAN Zheng LIU Aihua KUAI Linping
        Vol. 35, Issue 1, (2012)
        摘要：In this paper,atmospheric dispersion of 131I from a loss of coolant accident(LOCA) at the proposed Taohuajiang nuclear power plant(NPP) is simulated with the CALPUFF modeling system.The following results are obtained:(1) Within a few hours after the accident,at the grid point in the downwind direction,which is about 8 km away from the source,the 131I concentration forms a peak of air-time integration activity,because the altitude is as high as effective height of the source,while it is the highest in the downwind direction.(2) Among the three chemical forms of iodine,elemental iodine is the most likely to deposit,with the same contour distribution of deposited activity in the ground as the time-integrated air concentration.(3) The dose equivalent resulting from 131I internal exposure caused is far greater than external exposure,hence the need of,should a LOCA occur,preventing radioactive materials from entering human body via the respiratory tract,oral cavity and skin wound,so as to greatly reduce the 131I radiation dose equivalent.  
        关键词：CALPUFF;Atmospheric dispersion;Nuclear accident;Taohuajiang nuclear power plant   
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        发布时间：2021-03-05
      • SHEN Yi HU Jun
        Vol. 35, Issue 1, (2012)
        摘要：ingle molecule measurements have transformed our view of biomolecules.Owing to the ability of monitoring the activity of individual molecules,we now see them as uniquely structured,fluctuating molecules that stochastically transition between frequently many substrates,as two molecules do not follow precisely the same trajectory.Indeed,it is this discovery of critical yet short-lived substrates that were often missed in ensemble measurements that has perhaps contributed most to the better understanding of biomolecular functioning resulting from single molecule experiments.In this paper,we give a review on the three major techniques of single molecule force spectroscopy,and their applications especially in biology.The single molecular study of biotin-streptavidin interactions is introduced as a successful example.The problems and prospects of the single molecule force spectroscopy are discussed,too.  
        关键词：Single molecule force spectroscopy;Optical tweezers;Magnetic tweezers;Atomic force microscopy;Biotin-streptavidin bonds   
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        发布时间：2021-03-05
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