最新刊期
卷 0 ， 期 0 ， 2020
- 摘要：According to design of the SSRF linac,it is operated at 1 nC of beam current,2 Hz of repetition rate and 1 ns of pulse width.Nowadays,more and more synchrotron radiation facilities are operated in Top-up mode which requests the linac to work at weak beam current.This implies that in the same repetition rate and pulse width,the current shall be as weak as possible.In this paper,we report our efforts for running the SSRF linac at weak beam current.After theoretical calculation and experiments for weak beam current operation of the linac it is operated at 0.1 nC of current in Top-up mode.关键词：Linac;Top-up;Weak beam current
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发布时间：2021-04-09 - 摘要：Hydrostatic leveling system,used mainly in survey and alignment technology in particle accelerator and monitoring the tides is introduced in this paper.Based on the theory about the ocean tide and earth tide,we analyze effects of the earth tides on a hydrostatic leveling system.From the data obtained from an HLS,and their F are,and finally we verify the influence of the tides of planet earth.关键词：Hydrostatic leveling system;Planet earth tide;Precision engineering survey;Alignment
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发布时间：2021-04-09 - 摘要：In R&D of a GEM detector for X-ray imaging,many methods of baseline acquisition and zero-suppression threshold setting have been studied.In this paper,by comparing the methods to measure baseline of GEM detector are compared,an appropriate method to obtain the zero compress thresholds is used for high count rate application of the GEM detector,with better statistics,which improves the quality of 2-D images.The method can be a general reference for other detectors.关键词：GEM;Baseline;Zero compression
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发布时间：2021-04-09 - 摘要：A new numerical simulation method according to distorted crystal optical theory was used to predict the direct-cooling crystal monochromator optical properties(crystal Darwin width) in this study.The finite element analysis software was used to calculate the deformated displacements of DCM crystal and to get the local reciprocal lattice vector of distorted crystal.The broadening of direct-cooling crystal Darwin width in meridional direction was estimated at 4.12 μrad.The result agrees well with the experimental data of 5 μrad,while it was 3.89 μrad by traditional calcultion method of root mean square(RMS) of the slope error in the center line of footprint.The new method provides important theoretical support for designing and processing of monochromator crystal for synchrotron radiation beamline.关键词：Double crystal monochromator;Local reciprocal lattice vector;Darwin width;Numerical simulation;Distorted crystal
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发布时间：2021-04-09 - 摘要：In this paper,a motor control system,formed by a S3C2440 computer,the Linux operating system and a MAXnet motor controller,is developed in EPICS at SSRF(Shanghai Synchrotron Radiation Facility).A detailed analysis of the system design,and software development,are provided.It indicates that an ARM-based motor control system is feasible.Test results show that it has an equivalent performance in position control,with greatly reduced cost and volume,though the time response is not as good as the present motor control system.It provides a reference for designing new motor control systems of SSRF.关键词：Motor control;ARM;EPICS;SSRF
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发布时间：2021-04-09 - 摘要：The power supply digital controllers of Shanghai Synchrotron Radiation Facility(SSRF) make use of the PWM(pulse width modulation) wave as the feedback to the power-electrical devices,so as to obtain constant current of high accuracy and stability.The design of PWM wave generation structure in FPGA is good for a compact controller,and the reduction of the usage of Integrated Circuits(ICs) decreases the interference from the noise among the ICs,hence better performance of the controller.In addition,FPGA can be programmed circularly at any time,so as to optimize the structure design and make a maximum use of the advantage of FPGA.As a part of transplanting the complete function of the DSP(digital signal processor/processing),realizing the generation of PWM wave in FPGA is feasible.In this paper,we report progress in this regard at SSRF.关键词：FPGA;PWM;Timer;Comparator
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发布时间：2021-04-09 - 摘要：In this work,single event effects and total ionizing dose effects of typical VDMOSFET irradiated by 60Co γ-rays and 252Cf source were studied.The single event burnout and single event gate rupture(SEB/SEGR) effects were investigated,and the relationship between drain-source breakdown voltage and ionizing dose was obtained.The results showed that the VDMOSFET devices were sensitive to SEB and SEGR,and measures to improve their resistance to SEB and SEGR should be considered seriously for their space applications.The drain-source breakdown voltage was sensitive to total ionizing dose effects as the threshold voltage.In assessing the devices’ resistance to the total ionizing dose effects,both the threshold voltage and the drain-source breakdown voltage should be taken into account.关键词：VDMOSFET;Single event burn-out;Single event gate-rupture;Total ionizing dose effects
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发布时间：2021-04-09 - 摘要：For studying single event effect of the high-voltage radiation-hardened power VDMOS devices,two types of N-channel power VDMOS devices of the breakdown voltage 400 V and 500 V for satellite applications,developed with radiation-hardened technology,were irradiated to 105 cm–2 by 255 MeV 127I ions at dose rate of 7×103 cm–2.s–1.Single event gate rupture(SEGR) effect of the power VDMOS devices was investigated.The results showed the power VDMOS devices were of better resistance to single event effect.No single event effects were found at the gate-source voltage of 0 V and the drain-source voltage of the breakdown voltage.The experimental results provided a reference for space application of the power VDMOS devices,and were of importance for further improvement of the design and for developments of the other types of radiation hardened VDMOS devices.关键词：Power VDMOS device;SEGR effect;Accelerator;Dose rate
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发布时间：2021-04-09 - 摘要：For electron accelerator of the high frequency high voltage type,a beam-scanning power supply with a peak voltage of 190 V and peak current of 16 A has been developed at Shanghai Institute of Applied Physics.It has a pulse width modulation(PWM) and a Buck circuit,with the H-bridge inverter driver of IRS2453D and IR2110.Output voltage of the power supply can be adjusted continuously,and over-current protection can be realized.In this paper,we report power supply design and test results.关键词：Switching power supply;Losed-loop negative feedback;H-bridge inverter circuit;Current linearity error
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发布时间：2021-04-09 - 摘要：The retention time of Xe and Kr can be varied by changing the flow rate of carrier gas and temperature of the chromatography column packed with 5A molecular screen.It can be used for separating the noble gases.Test results show that an enhanced decontamination factor can be observed by extending the interval between retention times of Kr and Xe.Over 95% of the Kr and Xe can be absorbed by active carbon at –80oC.关键词：Preparative chromatography;Krypton;Xenon;Separation
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发布时间：2021-04-09 - 摘要：The behavior of hydrogen-absorption of Zr9Ni11 was studied experimentally in multi-cycle hydrogen absorption and desorption at room temperature under low hydrogen pressure.The results showed that the hydrogen absorption of the alloy was high,though it decreased slightly with increasing number of the cycles.The reaction rate was fast,though it decreased with the hydrogen pressure decreasing.Surface of the alloy became rough,and the composition changed after hydrogenation,which maybe the reason of degraded capability of hydrogen absorption.The Zr9Ni11 can be a good candidate for removing tritium in the air.关键词：Zr9Ni11;Tritium;Character of kinetics
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发布时间：2021-04-09 - 摘要：In this work,we investigated the feasibility of automated synthesis of(S-[11C]-methyl)-D-cysteine(11C-D-MCYS) as positron emission tomography tracer for tumor imaging.11CH3I was prepared by substitution reaction of HI with 11CH3OH,which was obtained from the reaction of LiAlH4 with 11CO2.11C-D-MCYS was produced by 11C-methylation of the precursor D-cysteine with 11CH3I and purification on commercial Sep Pak C18 cartridges.The uncorrected radiochemical yield of 11C-D-MCYS from 11CH3I was over(51±4)%,the radiochemical purity of 11C-D-MCYS was more than 99%,and the total synthesis time was about 12 min.PET imaging studies showed that 11C-D-MCYS had high uptake in the S180 sarcoma-bearing tissues,but low uptake in inflammatory tissues.It seems that 11C-D-MCYS is a potential PET tracer for tumor imaging.关键词：(S-[11C]-methyl)-D-cysteine;Inflammation;Tumor;PET imaging;18F-FDG
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发布时间：2021-04-09 - 摘要：Histamine-indomethacin(HIS-IN) was labeled with 131I by chloramine-T method.Thin-layer chromatography(TLC) was performed to evaluate the labeling ratio,radiochemical purity and stability of 131I-HIS-IN,using silicagel GF254 coated on glass plates,with chloroform and methanol being the mobile phase.The biodistributions of 131I-HIS-IN in Lewis pulmonary tumor model mice and normal mice were examined,and therapeutic effect of 131I-HIS-IN on mice with Lewis pulmonary tumor was studied.The results showed that radiochemical purity of the 131I-HIS-IN was 98%,and the highest %ID.g–1 of tumor tissue was 4.73±0.07 at 4 h,while the tumor/blood ratios were 2.95±0.30 at 8 h,2.67±0.62 at 12 h and 3.54±0.54 at 16 h.The ratios,and the necrotic tissue cells,increased with the post-injection hours.Therefore,131I-HIS-IN can be a new radioactive drug for tumor therapy.关键词：Histamine-Indomethacin;Iabeling;Lewis pulmonary tumor;Biodistribution
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发布时间：2021-04-09 - 摘要：Performance and imaging mode of atomic force microscope(AFM) have been in continuous development and now AFMs are operated in contact mode,tapping mode,or non-contact frequency-modulation mode.A non-contact frequency-modulation AFM achieves high resolution,and the sample distortion is greatly reduced because of the very small interaction force between the tip and sample.In this paper,we give a review on high resolution imaging of non-contact frequency-modulation AFM in vacuum and in physiological condition for better application in biology.Applications of the system in structural biology using the DPPC bilayer and IgM are given as samples.关键词：Atomic Force Microscope;Non-contact;High resolution;Frequency modulation
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发布时间：2021-04-09 - 摘要：In this paper,we study dynamical screening effects in T-shaped semiconductor quantum wire by Green’s Function theory at finite temperature.To clarify dynamical screening effects due to electron-hole plasma,the self-energy of T-shaped semiconductor quantum wire is calculated based on dynamically screened Coulomb potential.The energies of electron and hole,and the relation between the electron and hole energies and cross-section of quantum wire,are discussed.The results show that quasi-one-dimensional system has strong quantum confinement,which enhances the Coulomb interaction among carriers.Due to strong scattering among electrons,large band-gap renormalization effect and finite life-time of electrons are induced by dynamical screening effects.Compared to results by quasi static approximation,we find that holes are less affected by the dynamical screening effects.关键词：Semiconductor quantum wire;Quantum confinement;Coulomb interaction;Dynamical screening effect;Band renormalization
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发布时间：2021-04-09 - 摘要：One-dimensional(1D) semiconductor nanostructures have attracted considerable attention because of their unique optical and electronic properties.Due to the direct conduction pathways in 1D nanostructures versus electron hopping in nanopartile system,the materials are promising photoelectrodes for photoelectrochemical(PEC) water decomposition.TiO2 nanorods are proved to have nice PEC performance.In this work,TiO2 nanorod arrays were synthesized by hydrothermal method on substrate of fluorine-doped tin oxide glass.Effect of activation temperature on photoactivity of the TiO2 nanorods was investigated,and photo-to-hydrogen efficiency of the photoelectrode was calculated as 0.12%,the best of all under the same conditions.关键词：PEC water splitting;One-dimensional(1D) nanostructures;TiO2;Nanorod
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发布时间：2021-04-09 - 摘要：We conducted a study to characterize the antimicrobial properties of SWNTs to B.subtilis in a saline solution or in a LB culture.Dimensions and the antibacterial ability of SWNTs in a saline solution were different from those in a LB culture.Transmission and scanning electron microscopes were used to characterize the SWNTs structure with and without LB culture.The antibacterial ability of SWNTs was affected by the environment of bacterial growth.The antibacterial mechanism of SWNTs was studied,too.关键词：SWNTs;LB culture;Antibacterial
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发布时间：2021-04-09
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