最新刊期
卷 0 ， 期 0 ， 2020
- 摘要：On a infrared beamline,where the IR transmits through CVD diamond window,multiple reflections occurs between the front and back surfaces of the window.This phenomenon can give rise to modulation of transmission ratio at different wavenumbers,and produce extra noise in the Fourier transform infrared spectroscopy.In this paper,influence on the transmission ratio is studied at different CVD diamond parameters,such as wedged angle,installation angle,diameter and thickness,based on specifications of the BL01B infrared light source at Shanghai Synchrontron Radiation Facility(SSRF).The results show that the CVD diamond parameters affect the transmission ratio greatly in synchrotron radiation infrared beamline.关键词：Synchrotron radiation infrared beamline;CVD diamond;Wedged angle;Transmission
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发布时间：2021-03-05 - 摘要：A real-time beam profile diagnostic platform based on embedded ARM and FPGA has been developed for beam cross-section measurement of the SDUV-FEL(Shanghai Deep Ultra-violate Free Electron Laser).In this paper,we report the interface design of the stepper motor control subsystem.The interface is implemented through the ARM external bus,and the driver for FPGA device is developed under Linux operating system.The interface board is designed and fabricated from chips level in order to evaluate the hardware performances of different functional modules.Test results of the motor control subsystem show that the motor location resolution is about 2 μm for the interface board.The architecture is scalable and suitable for further application in FEL facility.关键词：Beam profile diagnostic;Stepper motor;Free-electron laser;Embedded system
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发布时间：2021-03-05 - 摘要：A Hall probe composed of three planar hall sensors is the fundamental tool to measure three-dimensional magnetic field value.The factors affecting accuracy of the measurement,such as the ambient temperature,manufacturing quality of the probe and so on,must be corrected by calibrating the probe effectively.In this paper,we use a rotatable standard electromagnet to calibrate the probe and correct the temperature and planar Hall effect.The calibrated probe has been used successfully at Shanghai Synchrotron Radiation Facility in magnetic field measurements of the elliptically polarized undulators,where the horizontal and vertical magnetic fields co-exist.关键词：Hall probe;Calibration;Planar Hall effect
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发布时间：2021-03-05 - 摘要：In this article,relationship between the thickness of a tube 3He proportional counter and its detection efficiency are studied by Monte Carlo simulation of monoenergetic neutron and Hess spectrum neutrons.A 5-cm thickness of the polyethylene modulator is thus determined.Finally,utilizing a 252Cf neutron source and the natural neutron background,the detector sensitivity is calibrated.关键词：3He proportional count tube;Polyethylene;Neutron;Geant4
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发布时间：2021-03-05 - 摘要：In this study,dosimetric characteristics of percentage depth dose,beam profiles,dose rate on the central axis,and total scattering factor,were estimated by using BEAMnrc and DOSXYZnrc Monte Carlo code,for 6 MV photon beams from a SIEMENS linac with and without flattening filter.The results showed that the percentage depth dose of flattening filter free(FFF) beam were lower than flattening filter(FF) beam;the dose rate on central axis was higher than FF beam,and the ratio of FFF/FF decreased with field size and depth increasing.Besides,the width of penumbra for FFF beam was slightly smaller than that of with FF case.And the variation of total scatter factor showed the flattening filter free mode had smaller depth dependence than flattening filter mode.Our study shows that the beams without flattening can be advantageous in clinical applications.关键词：Unflattened beam;Linear accelerator;Monte-Carlo method;Flattening filter
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发布时间：2021-03-05 - 摘要：The absorbed dose in quartz samples irradiated by β rays in TL or OSL dating protocol was simulated using the EGSnrc /DOSRZnrc code.Effects of thickness and grain size of the quartz samples on the absorbed dose were evaluated with the samples of Φ0.97 cm×(10–500) μm,in grain size of 60–300 μm.The results show that the absorbed dose in quartz is relative to the sample thickness,and the maximum difference of the relative dose can be up to 10%.The absorbed dose is relative to the grain size,too.The relative dose increases with decreasing grain size,and the maximum difference can be up to 19%.These factors should be considered in the dating.关键词：Quartz;β absorbed dose;Monte Carlo simulations
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发布时间：2021-03-05 - 摘要：Chemical species of Am in contaminated desert soil particles was investigated by using the standard sequential extraction procedures,so as to assess the mobility of Am in soil in nuclear accident.It was found that 19.5% 60% of Am was bound to reducible fraction.The content of 241Am bound to oxidisable and residual fraction increased with decreasing particle size.High correlations were found between the Am concentration and amount of organic,Illite,Fe2O3 matter in soil particles.The results showed that Am is difficult to migrate in this site.Organic and mineral matters play an important part for Am accumulation in soils.关键词：Desert soil;Particles;Am;Chemical species
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发布时间：2021-03-05 - 摘要：The Compton spectrum for 0.8–6 MeV-rays in plastic scintillation fibers was studied by using Geant4.7.0.The relationship between energy resolution and fiber radius was discussed.The cross talks between fibers were also studied by using a simple model.The results show that for appropriate radius,a better Compton spectrum can be obtained.The best energy resolution can achieve 8.7% with the radius of 15–35 mm.关键词：Geant4;Plastic scintillation fiber;Energy resolution
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发布时间：2021-03-05 - 摘要：The recognition for γ-ray sources was studied using NaI(Tl) spectrum.A program compiled by VB6.0 was developed to identify γ-ray sources by comparing their spectra with those in a database.Experiment test results show that the γ-ray source identification can be achieved by using the total count mode or full-energy peak counts.关键词：Recognition for γ radiation source;NaI spectrometer;Full-energy peak
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发布时间：2021-03-05 - 摘要：In this article,the relationship between static SEU(Single Event Upset) rate and dynamic SEU rate in microprocessors for satellites is studied by using process duty cycle concept and fault injection technique.The results are compared to in-orbit flight monitoring data.The results show that dynamic SEU rate by using process duty cycle can estimate in-orbit SEU rate of microprocessor reasonable;and the fault injection technique is a workable method to estimate SEU rate.关键词：Microprocessor for satellites;SEU rates;Process duty cycle;Fault injection
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发布时间：2021-03-05 - 摘要：Based on advantage of cyclic neutron activation of 20F(t1/2=11.03 s),cyclic neutron activation analysis(CNAA) and three traditional methods,i.e.UV-vis spectroscopy,fluorine ion selective electrode,and chromatography of ions,were used to determine fluorine concentration in standard reference materials of tea(GBW10016).Compared with the three traditional methods,CNAA is accurate,sensitive,time-saving,little sample amount,strong traceability and good anti-interference.Fluorine concentrations in 16 commercial teas of four categories were determined by using CNAA.The results showed that fluorine concentrations of brick tea,black tea,oolong tea and green tea are 60 276,54 66,37 59 and 34 49 mg/kg,respectively.It was also found that the fluorine concentrations in different tea categories are likely attributed to their raw materials and production process.Fluoride concentration in one tea product was 276 mg/kg,while the national standard is ≤200 mg/kg.关键词：Cyclic neutron activation analysis;Tea;Fluorine
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发布时间：2021-03-05 - 摘要：Positron radioactive molecular imaging can be used to do early diagnose of Parkinson’s disease,a senile neurodegenerative disease,and the method has been accepted by more and more doctors and patients.In this paper,we give a review on positron radioactive molecular imaging agents in clinical application and research of Parkinson’s disease.关键词：Positron radioactive molecular imaging agents;Diagnosis;Parkinson’s disease
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发布时间：2021-03-05 - 摘要：18F-FDG PET/CT data of 44 patients with small intestine disease(malignant,25;benign,19) were analyzed retrospectively.All results were proved by pathological,or diagnostic therapy and/or clinical follow-up.Visual and quantitative[intestinal wall thickness(IWT)] and semiquantitative methods [standardized uptake value(SUV)] were used to analyze the imaging features.The SUVmeanand IWT were taken as the diagnostic threshold value for malignant when the Youden’s index(YI) was maximum.The diagnostic test evaluation was compared with the final diagnostic results.The following results were obtained.(1) The 18F-FDG PET/CT imaging signs of small intestine carcinoma presented as intestinal local mass formation(84.00%),local wall thickening(76.00%),stenosis(25.00%),obstruction(32.00%) and enlargement of mesenteric lymph nodes(72.00%).But the incidence rates of these signs in the benign lesions were 31.58%,42.11%,10.53%,15.79% and 52.63%,respectively.Only the signs of intestinal local mass formation(χ2=10.40,p<0.01) and local wall thickening(χ2=3.90,p<0.05) between intestinal malignant and benign lesions were of significant statistic difference.(2) The IWT of intestinal malignant and benign lesions was 7.53±3.24 mm and 14.24±2.02 mm(t=2.66,p<0.01),respectively.When YImax =0.589,the diagnostic threshold of IWT was 9.5mm.The sensitivity,specificity and accuracy were 80.00%,78.95% and 79.55%,respectively.(3) The SUVmeanof intestinal malignant and benign lesions was 3.55±1.84 and 6.98±3.62(t=3.77,p<0.01) respectively.When YImax =0.379,the diagnostic threshold of SUVmean was 3.65.The sensitivity,specificity and accuracy were 80.00%,57.89% and 70.48%,respectively.(4) Taking the intestinal mass formation as the diagnostic standard of malignant lesions,the sensitivity,specificity and accuracy were 84.00%,78.95% and 81.82%,respectively.The YImax was 0.630.(5) Taking the intestinal mass formation and SUVmean of <3.65,and local wall thickening or IWT <9.50 mm as the main evidence of the intestinal malignant lesions,the sensitivity,specificity and accuracy were 96.00%,89.47% and 93.18%,respectively.The YImaxwas 0.855.It can be used as the main evidence to differentiate the small intestine primary malignant and benign lesion with the 18F-FDG PET/CT imaging qualitative and quantitative signs for the intestinal mass formation,at SUVmean<3.65,and local wall thickening or IWT <9.50 mm.关键词：Small intestine neoplasms;Tomography;Emission computed;18F-Deoxyglucese;Diagnosis
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发布时间：2021-03-05 - 摘要：An active carbon absorber is mainly used for radioactive iodine absorption and gas purification in an nuclear power plant.According to technical requirement of the Type Ⅲ absorber developed at Shanghai Nuclear Engineering Research and Design Institute,finite element analysis(FEA) was used for its mechanics analysis.Static analysis under dead weight,design pressure and operating pressure,modal analysis,and seismic analysis were performed.The structure integrity of Type Ⅲ active carbon iodine absorber was satisfied under different service conditions.The structure weakness was clarified under static and seismic loads,and the structure design was improved based on the FEA results.关键词：Nuclear gas and gas purification system;Ⅲ-type active carbon iodine absorber;Structural integrity analysis
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发布时间：2021-03-05 - 摘要：The proton therapy facility was designed in China for the first time.Elastic deformation of driving rollers at contact area will arise from hugeness and ponderousness of the facility.For the deformation,the shape of the contact area changes from theoretical line to the surface and the true transmission ratio cannot agree with the theoretical value,which results in the reduction of transmission accuracy.The approximate deformation tendency of driving rollers was obtained according to the elastic slide theory and hertz contact theory.A finite element analysis(FEA) model for driving rollers of the proton therapy facility was performed by simulating the boundary conditions and the force conditions of driving rollers,using ANSYS WORKBENCH software.Effective basis was provided for the design and adjustment of the proton therapy facility based on FEA and study of the mechanical behavior of rollers.关键词：Proton therapy;Driving roller;Finite element analysis
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发布时间：2021-03-05 - 摘要：In this paper,basic principle of RF-knockout(RFKO) is analyzed for slow beam extraction from the medical proton accelerator,with the amplitude growth mechanism of RFKO method.The amplitude modulation(AM) function model is proposed to obtain a certain uniformity of the beam magnitude.The conditions necessary for a uniform extracted beam,which include RFKO kick angle vs proton numbers of the beam,and kick angle vs the extraction time.Using the WinAGILE code,giving an initial particle momentum distribution,beam distribution is simulated.The relationship among tune deviation,sextupole magnet strength and beam are also simulated.关键词：Slow extraction;AM;Proton therapy;RF-Knockout
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发布时间：2021-03-05 - 摘要：In this paper,we report the configuration of frequency sweeping mode and PI feedback control in the low-level RF system of the proton synchrotron for proton therapy.Altera Stratix II FPGA and AD9858 are adopted to get the direct digital synthesizer(DDS) signal of frequency sweeping mode by compiling Verilog HDL code.A PI feedback algorithm is designed to control the amplitude and phase of cavity voltage,with high precision and stability.关键词：Digital Low-Level RF;DDS;FPGA;Digital PI control algorithm.
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发布时间：2021-03-05
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