Research of On-line Analytical Method of Trace Oxygen and Water in Argon

Metal sodium has an active chemical quality. When it is used as a coolant in a fast neutron reactor, it must be protected by a cover gas argon for safety operation of the reactor. But oxygen and water in argon can produce chemical reaction with sodium. Then sodium hydroxide, sodium oxide and hydrogen can be produced. This will be harmful to the safety operation of reactor. The purpose of controlling a level of impurity in the cover gas is for controlling a level of impurity in sodium. The research is to find an on-line determining method and a sampling system to monitor     

Comparison of the Free Volume of LiCl-Added SPPO Membrane and SPPO-PES Blend Membrane by Positron Annihilation Method

Positron annihilation lifetime spectroscopy （PALS） is a powerful technique for the study of free volume in polymers. The lifetime of ortho-positronium （o-Ps）, a bound state of an electron and a positron, can be used to assess the pore size, while the intensity can be used to characterize the number of pores. Based on the values of the long-lived o-Ps components in the lifetime spectra, the radii and fractional free volumes of sulfonated poly （2,6-dimethyl-1,4- phenyleneoxide） （SPPO） membranes with added LiCl and SPPO-PES （Polyethersulfone） blend were compared. Free volume radii in both kinds of membranes are discussed.     

Criterion of Magnetic Saturation and Simulation of Nonlinear Magnetization for a Linear Multi-core Pulse Transformer

The linear multi-core pulse transformer is an important primary driving source used in pulsed power apparatus for the production of dense plasma owing to its compact,relatively low-cost and easy-to-handle characteristics.The evaluation of the magnetic saturation of the transformer cores is essential to the transformer design,because the energy transfer efficiency of the transformer will degrade significantly after magnetic saturation.This work propses analytical formulas of the criterion of magnetic saturation for the cores when the transformer driver practical loads.Furthermore,an electric circuit model based on a dependent source treatment for simulating the electric behavior of the cores related to their nonlinear magnetization is developed using the initial magnetization curve of the cores.The numerical simulation with the model is used to evaluate the validity of the criterion.Both the criterion and the model are found to be in agreement with the experimental data.     

Vertical Instability in EAST： Comparison of Model Predictions with Experimental Results

Growth rates of the axisymmetric mode in elongated plasmas in the experimental advanced superconducting tokamak （EAST） are measured with zero feedback gains and then compared with numerically calculated growth rates for the reconstructed shapes. The comparison is made after loss of vertical position control. The open-loop growth rates were scanned with the number of vessel eigenmodes, which up to 20 is enough to make the growth rates settled. The agreement between the growth rates measured experimentally and the growth rates determined numerically is good. The results show that a linear RZIP model is essentially good enough for the vertical position feedback control.     

Preparation of Copper Nanoparticles Using Dielectric Barrier Discharge at Atmospheric Pressure and its Mechanism简

Dielectric barrier discharge （DBD） cold plasma at atmospheric pressure was used for preparation of copper nanoparticles by reduction of copper oxide （CuO）. Power X-ray diffraction （XRD） was used to characterize the structure of the copper oxide samples treated by DBD plasma. Influences of H2 content and the treating time on the reduction of copper oxide by DBD plasma were investigated. The results show that the reduction ratio of copper oxide was increased initially and then decreased with increasing H2 content, and the highest reduction ratio was achieved at 20% H2 content. Moreover, the copper oxide samples were gradually reduced by DBD plasma into copper nanoparticles with the increase in treating time. However, the average reduction rate was decreased as a result of the diffusion of the active hydrogen species. Optical emission spectra （OES） were observed during the reduction of the copper oxide samples by DBD plasma, and the reduction mechanism was explored accordingly. Instead of high-energy electrons, atomic hydrogen （H） radicals, and the heating effect, excited-state hydrogen molecules are suspected to be one kind of important reducing agents. Atmospheric-pressure DBD cold plasma is proved to be an efficient method for preparing copper nanoparticles.     

A Brief Presentation of Lanzhou Penning Trap Control System

LPT (Lanzhou Penning Trap) is an ion-trap facility in Lanzhou, China. As ions can be cooled to an extremely small phase space and can be stored for a very long time, ion traps are a perfect instrument for high precision mass measurements. A system with specialized electronics for LPT is under construction now. This system could be used for voltage and timing control to make ions moving in a special mode, and the data acquisition and analysis online/offline could be achieved in the mean time. The requirements of control system, the distribution of hardware, the overview of software, and the latest progress of LPTCtrlSys (Lanzhou Penning Trap Control System) are presented.     

Preliminary Study on Sampling Behavior of Na and Mn in 4 CRMs

Sampling behavior of Na and Mn in 4 CRMs was characterized at sample sizes of 0.8 to 1.4 mg by instrumental neutron activation analysis （INAA）. The CRMs studied are andesite GBW07104 （GSR-2）, shale GBW07107 （GSR-5）, soil GBW07408 （GSS-8）, stream sediment GBW07309 （GSD-9）, already certified on regular minimum sample size （MSS） of 100-150 mg. The aim of the study is to identify the CRMs with satisfied homogeneity for Na and Mn at about 1 mg sample size, so as to be used for future study on sampling behavior of multielements and eventually produces new generation CRMs suitable for quality control of microanalysis.     

Calibration method of HLS’s sensor used in SSRF

The site of Shanghai Synchrotron Radiation Facility （SSRF） is of complicated geological conditions, and a system to monitor the uneven subsidence of foundation and key parts （different kinds of magnets） of the accelerators is a necessity. Considering actual conditions of the accelerator structure and the assembling place, a new type of sensor of hydrostatic levelling system （HLS） has been designed. In order to obtain the required measurement accuracy, every HLS＇s sensor was strictly calibrated. In this paper, we introduce the special calibration method to establish the HLS. The method has been used in the calibration for vessel sensor for SSRF.     

Implementing method of optimum front-end conditioner based on Butterworth filter

The front-end conditioner is an essential part of digital systems of nuclear spectrometer, which functions in two ways： （1） prevents saturation of the subsequent ADC; （2） limits the bandwidth of frequency to realize anti-aliasing. To realize the above-mentioned functions, an optimum front-end conditioner for a resistive feedback charge-sensitive preamplifier is designed. In the conditioner, the pole-zero compensation （P/Z compensation） technique was used to effectively filter signals from the preamplifier. The Butterworth filter was improved after the pole-zero position was optimally set up to shape the wave of output, which tallied with the whole system. The front-end conditioner can resolve the aberration of waveform of nuclear signals in a regular Butterworth filter. Compared with the traditional triple-pole filtering circuitry, the circuitry of this conditioner is more compact and flexible. Moreover, its output waveform is more symmetrical and the signal-to-noise ratio （SNR） is higher. The improvement in the resolution of spectrometer is also significant.     

Tidal effects on hydrostatic leveling system used in high precision alignment of particle accelerator

Hydrostatic leveling system（HLS） is widely used in precision engineering survey,especially the alignment of particle accelerator,and the tidal effects on the measurement accuracy of HLS is non-ignorable.thus studies on tidal effects on the HLS is vital.A set of HLS was installed in Jingxian seismostation for verifying the methods to handle the tidal effects on the readings of HLS.Harmonic analysis of the data recorded by HLS and DSQ water tube clinometers in Jingxian seismostation and contrastive analysis of the results are completed.The tilt tide can be well reflected in the data of the both instruments and the results are both reliable.The reasons of the difference between the results are analyzed in this paper.Besides,a validation study based on the measurement data of the HLS used in SPring-8 storage ring for tidal correction on the reading of HLS is completed.The research establishes a foundation for HLS to be applied in micron-level precision alignment of particle accelerator in the future.     

The role of high-energy computed radiography （CR） in radiotherapy

Computed radiography (CR) imaging has high irradiation tolerance and it is easy to archive CR images along with other image information by Digital Imaging and Communications in Medicine (DICOM) format,and to process them.CR can be used in radiation Quality Control (QC) task and verification of treatment setting-up.In this paper,the role of high-energy CR in radiation oncology is studied.The patients were imaged by CR system and EPID before radiotherapy.All verification images were acquired with 1-2 MU (Monitor Unit) using 6 MV X-rays.QC for a tinac was done with film and high-energy CR to collect the data on daily,weekly and monthly basis.The QC included Multileaf Collimators (MLC) calibration and mechanical iso-centre check.CR was also adapted to verify patient position,the film was used to compare with digitally reconstructed radiographs (DRR) and portal image from EPID.Treatment setting-up was verified based on the result of comparison.High quality verification images cou ld beacquired by the CR system.Comparing to EPID,the results showed that the system was suitable for practical use to acquire daffy verification images,and it was useful to fulfill part of quality assurance (QA) in radiation oncology.The quality of image acquired by the high-energy CR system is comparable or even better than DRRs and portal images.The final treatment set-up for the patients could be verified more accurately with the CR system.     

Radiation-induced damage in GaAs particle detectors

The motivation for investigating the use of GaAs as a material for detecting particles in experiments for high-energy physics (HEP) arose from its perceived resistance to radiation damage. This is a vital requirement for detector materials that are to be used in experiments at future accelerators where the radiation environments would exclude all but the most radiation resistant of detector types     

Use of Superconducting RF Systems in Low-Energy Accelerators

The basic problems of the development and construction of charged-particle accelerators using superconducting rf accelerating structures are discussed. The characteristics of the modular systems currently used in high-energy superconducting accelerators and their application to accelerators for tens or hundreds of MeV are examined. __________ Translated from Atomnaya Energiya, Vol. 99, No. 4, pp. 289–295, October, 2005.     

Induced radioactivity of structural materials in the development of an internuclear cascade initiated by 50 GeV protons

A facility for studying the radioactivity of structural materials exposed to high-energy protons is described. Experimental data on the nuclide composition of different structural materials are presented. The data obtained are important for the radiological safety of proton accelerators and they can also be used as reference data for verifying computational codes.     

高能闪光照相中陡坡准直体成像性能实验研究

在针对FTO样品的高能闪光照相实验中,比较了一般准直体与陡坡准直体对FTO样品的成像性能。结果表明,陡坡准直体对降低散射及缩小照射量量程非常有效,可得到层次分明的底片图像;采用一般准直体则无法得到有意义的样品图像。对实验进行了蒙卡模拟,模拟结果与实验结果一致。     

核电站安装工程质量管理研究

运用项目质量管理理论，结合秦山核电二期工程的建设实践对质量规划、质量保证和质量控制分别展开讨论，通过运用以上质量管理的理论和控制技术，在实际指导项目质量管理过程中起到了积极的作用，具有较强的实用性。     

Estimates of neutron leakage through penetrations of the cern intersecting storage rings by monte carlo albedo calculations

The monokinetic and multigroup Monte Carlo albedo methods applicable to estimating neutron leakage through penetrations in the shielding of high-energy accelerators are reviewed. They are used to calculate attenuation factors and dose levels in the tunnels of the CERN intersecting storage rings.     

Relativistic stabilized electron beam

The physical principles underlying the formation of a relativistic stabilized electron beam are presented and questions connected with the stability of such a configuration are discussed.Presented at the C.E.R.N. symposium (Geneva) on high-energy accelerators and meson physics (June,1956).     

Extraction of high-energy particle beams through the yoke of the synchrocyclotron magnet

A method of obtaining collimated beams of high-energy particles (in particular, pions) is described; this method makes use of the yoke of the synchrocyclotron magnet as the main shield against the direct radiation of the accelerator. The collimators, which are set into channels drilled in the yoke of the magnet, make it possible to obtain beams of pions with energies up to 400 Mev.Deceased.In conclusion, we wish to express our gratitude to A. V. Chestnoi and B. I. Zamolodchikov for valuable advice, to K. A. Baicher and S. I. Zhigoman for drilling the holes in the magnet yoke, and to P. T. Pavlov for the construction of the collimators which were installed in the yoke.     

Electron dumps for ITER HNB and DNB beamlines

The negative ion accelerators that produce the high-energy particle beams for the neutral injection systems for the International Tokamak Experimental Reactor (ITER) also produce unwanted particles such as electrons. These electrons are emitted in a wide angular spectrum that allows some of them to directly intercept sensitive beamline components such as the cryogenic pumps. As the electrons are also subject to backscattering, indirect interception always occurs. In this article the electron spectra produced by the Heating Neutral Beam (HNB) and Diagnostic Neutral Beam (DNB) accelerators are calculated. It is shown that these are very different. It is proposed to install electron dumps in the beamlines to intercept electron power directed towards inconvenient places in the HNB and DNB beamlines.