Dongguan Institute of Neutron Science

Dongguan, China

Dongguan Institute of Neutron Science

Dongguan, China
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Hu Z.-L.,CAS Institute of High Energy Physics | Hu Z.-L.,Dongguan Institute of Neutron Science | Zhou B.,CAS Institute of High Energy Physics | Zhou B.,Dongguan Institute of Neutron Science | And 4 more authors.
Wuli Xuebao/Acta Physica Sinica | Year: 2016

The Monte Carlo intra-nuclear cascade program CBIM has been developed for describing spallation reactions involving protons, neutrons and pions on complex nuclei. In order to describe cascade process, several simplifications and assumptions are made in the following: firstly, neither reaction, nor reflection, nor refraction, nor ionization will be taken into account before the incident particle enters into the target nucleus; secondly, target nucleus is regarded as being spherical and the atom number should be greater than 2; thirdly, the knocked nucleon is determined by cross section sampling; finally, in the center-of-mass frame, the scattering angle is sampled based on differential cross section distribution. The basis physics model is based on the above assumptions and Bertini intra-nuclear cascade model; meanwhile, nucleon-nucleon angle differential distributions of INCL in the center-of-mass frame are introduced to overcome the shortage of Bertini model. The interactions between nucleon and nucleon or between nucleon and pion, such as elastic scattering, pion production and charge exchange, are included in the code. In the particles collision, the nucleon density changes with the target nucleus radius; and the interaction cross sections refer to 22 kinds of experimental cross sections in Bertini model. The intra-nuclear cascades induced by 45-3500 MeV neutron, proton or pion below 2500 MeV can be simulated by this code. Finally, comparisons between experimental reaction cross section over the energy range 60-378 MeV, and some simulation results by MCNPX, GEANT4 and PHITS over the energy range 65-3000 MeV show that they are in reasonable agreement with the CBIM results over the broad energy range considered. © 2016 Chinese Physical Society.

Zhou X.-J.,CAS Institute of High Energy Physics | Zhou X.-J.,Dongguan Institute of Neutron Science | Zhou X.-J.,University of Chinese Academy of Sciences | Tao J.-Z.,CAS Institute of High Energy Physics | And 3 more authors.
Chinese Physics B | Year: 2017

The atomic pair distribution function (PDF) reveals the interatomic distance in a material directly in real-space. It is a very powerful method to characterize the local structure of materials. With the help of the third generation synchrotron facility and spallation neutron source worldwide, the PDF method has developed quickly both experimentally and theoretically in recent years. Recently this method was successfully implemented at the Shanghai Synchrotron Radiation Facility (SSRF). The data quality is very high and this ensures the applicability of the method to study the subtle structural changes in complex materials. In this article, we introduce in detail this new method and show some experimental data we collected. © 2017 Chinese Physical Society and IOP Publishing Ltd.

Yuan G.,University of Akron | Cheng H.,Dongguan Institute of Neutron Science | Han C.C.,CAS Institute of Chemistry | Han C.C.,Shenzhen University
Polymer (United Kingdom) | Year: 2016

In this feature article, we first make some simple reviews about the most popular theories for glass transition: 1) Free volume theory, 2) Entropy theory, 3) Götze's Mode coupling theory, and 4) Caging and Jamming theory. We address the issue of existing studies of glass transformations. Then, we review some special colloidal/polymer model systems which can give a repulsive potential together with an attractive potential and also large enough and slow enough, so we can study the structure (through microscopy and scattering techniques) and dynamics (mainly through rheology) changes as a function of temperature and volume fraction. We hope, this paper, with the study to explore the structural and dynamics along the path toward the equilibrium, can provide some information, stimulation, incentive, and guidance for future theoretical and experimental studies for glass transition of structural materials, especially for polymers, colloids and colloid/polymer systems. © 2017 Elsevier Ltd.

Zhou L.,CAS Institute of High Energy Physics | Zhou L.,Dongguan Institute of Neutron Science | Zhou L.,University of Chinese Academy of Sciences | Qu H.-M.,CAS Institute of High Energy Physics | Qu H.-M.,Dongguan Institute of Neutron Science
Chinese Physics C | Year: 2015

The monocrystalline silicon neutron beam window is one of the key components of a neutron spectrometer. Monocrystalline silicon is brittle and its strength is generally described by a Weibull distribution due to the material inhomogeneity. The window is designed not simply according to the mean strength but also according to the survival rate. The total stress of the window is stress-linearized into a combination of membrane stress and bending stress by finite element analysis. The window is a thin circular plate, so bending deformation is the main cause of failure and tensile deformation is secondary and negligible. Based on the Weibull distribution of bending strength of monocrystalline silicon, the optimized neutron beam window is designed to be 1.5 mm thick. Its survival rate is 0.9994 and its transmittance is 0.98447, which meets both physical and mechanical requirements. © 2015 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.

Jia D.,CAS Institute of Chemistry | Yang J.-F.,CAS Institute of Chemistry | Cheng H.,CAS Institute of High Energy Physics | Cheng H.,Dongguan Institute of Neutron Science | Han C.C.,CAS Institute of Chemistry
Acta Polymerica Sinica | Year: 2015

As a typical elastic scattering technique, laser light scattering results cannot precisely describe the solution structure when the samples absorb incident light. Therefore, commercial laser light scattering instrument has been modified and upgraded to utilize four independent lasers, e. g. 785 nm, 632.8 nm, 532 nm and 457 nm, respectively as the light sources. By switching the wavelengths of incident lasers to avoid the sample absorption, the instrument can be widely used in fluorescent/phosphorescence solution systems. Spherical polystyrene nanoparticles with and without fluorescent dyes are used to calibrate the modified instrument. It is found that the height of the normalized intensity-intensity time correlation function decreases with the increase of the scattering angle when the sample absorbs the incident laser light. Such a correlation function fails to describe the sample solution structure, because the corresponding hydrodynamic radius distribution shows two modes and the average characteristic line width 'Γ' versus the square of scattering vector q2 does not fit a good linear relationship any more. Therefore, another laser which is not absorbed by the sample is used to do the calibration again. The corresponding intensity-intensity time correlation functions and the fitting results can precisely describe the solution structure. Fluorescence correlation spectroscopy (FCS) is also conducted to further prove the results obtained from the modified laser light scattering instrument are precise and accurate. © 2015, Science Press. All rights reserved.

He Y.,CAS Institute of High Energy Physics | He Y.,Dongguan Institute of Neutron Science | Wang C.,CAS Institute of High Energy Physics | Wu X.,CAS Institute of High Energy Physics | Wu X.,Dongguan Institute of Neutron Science
He Jishu/Nuclear Techniques | Year: 2014

Background----.: EtherCAT (Ethernet Control Automation Technology) is a kind of real-time Ethernet fieldbus protocol for industrial automation. The control system of many large-scale scientific facilities such as Beijing electron-positron collider (BEPCII), Chinese spallation neutron source (CSNS) was designed based on EPICS (Experimental Physics and Industrial Control System). Purpose----.: The aim is to implement EtherCAT as a real-time high speed control system solution for the EPICS based control system. Methods----.: The communication between EPICS IOC (Input/Output Controller) and EtherCAT devices was realized by using the OPC (Object Linking and Embedding for Process Control) Gateway driver. A real-time temperature monitoring appliance was taken as testing example. Results----.: The test results show that the communication between EPICS IOC and EtherCAT devices using the OPC Gateway driver is efficiently implemented. Conclusion: EtherCAT devices can be applied to communicate with the EPICS IOC to achieve real-time high-speed control by using the OPC Gateway driver. ©, 2014, Science Press. All right reserved.

Huang M.-Y.,CAS Institute of High Energy Physics | Huang M.-Y.,Dongguan Institute of Neutron Science
Chinese Physics C | Year: 2016

We study the detection of accelerator neutrinos produced at the China Spallation Neutron Source (CSNS). Using the code FLUKA, we have simulated the production of neutrinos in a proton beam on a tungsten target and obtained the yield efficiency, numerical flux, and average energy of different flavors of neutrinos. Furthermore, detection of these accelerator neutrinos is investigated in two reaction channels: neutrino-electron reactions and neutrino-carbon reactions. The expected numbers of different flavors of neutrinos have also been calculated.

Sun B.,CAS Institute of High Energy Physics | Sun B.,Dongguan Institute of Neutron Science | Tang J.,CAS Institute of High Energy Physics | Tang J.,Dongguan Institute of Neutron Science | And 4 more authors.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2015

In order to achieve the extremely high reliability and availability in superconducting linacs required by some applications such as in accelerator-driven systems (ADS), a fault tolerance design is usually pursued. With the example of the China-ADS main linac, the failure effects of key elements such as RF cavities and focusing elements in different locations along the linac have been studied and the schemes of compensation by means of the local compensation-rematch method have been proposed. For cavity failures, by adjusting the settings of the neighboring cavities and focusing elements one can make sure that the Twiss parameters and beam energy are recovered to the nominal ones at the matching point. For solenoid failures in the low energy section, a novel method by using a neighbor cavity with reverse phase is used to maintain simultaneous acceleration and focusing in both the transverse and longitudinal phase planes. For quadrupole failures in the warm transitions in the high energy section, triplet focusing structure is adopted which can be converted locally into a doublet focusing in case of one quadrupole failure and the rematch method is proven very effective. With macro-particle simulations by TraceWin, it is found that the normalized rms emittance has no obvious growth and the halo emittance has modest growth after applying the local compensation-rematch in the cases mentioned above. In addition, a self-made code based on MATLAB has been developed to double check the simulations by TraceWin for the local compensation and rematch method. © 2015 Elsevier B.V. All rights reserved.

Ren H.,Hunan University | Ren H.,Dongguan Institute of Neutron Science | Zhao Y.,Dongguan Institute of Neutron Science | Wen S.,Hunan University | And 2 more authors.
He Jishu/Nuclear Techniques | Year: 2015

Background: China Spallation Neutron Source (CSNS) is a scientific facility used for studying neutron characteristics and detecting the micro structure of materials. Purpose: This study aims to obtain the position and charge information of incident neutrons for the multipurpose reflectometer of CSNS. Methods: An electronic readout system is designed to detect and handle the signals from a two-dimensional Multi-Wire Proportional Chamber (MWPC). An Application Specific Integrated Circuit (ASIC) chip VA64tap2.1, made by IDEAS company, is applied to get the position and charge information in MWPC. The readout system is comprised of a VA64tap2.1-based readout board, a firmware for Field-Programmable Gate Array (FPGA) and an application program in PC. Results: The tests results show that the system can fulfill the readout requirements, and the ASIC chip is of low noise (less than 0.35fC when connected the MWPC detector), low power dissipation (less than 0.3 mW per channel), large dynamic range (-200-+160fC) and high integration (64 channels/board). Conclusion: This electronic readout system can be used in particle position detection. ©, 2015, Science Press. All right reserved.

Zou Y.,Anhui University of Science and Technology | Zou Y.,CAS Institute of High Energy Physics | Tang J.,Anhui University of Science and Technology | Tang J.,CAS Institute of High Energy Physics | And 2 more authors.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2016

This paper proposes a novel method for resonant slow extraction in synchrotrons by using special anti-symmetric sextupole fields, which can be produced by a special magnet structure. The method has potential in applications demanding very stable slow extraction from synchrotrons. Our studies show that slow extraction at the half-integer resonance by using an anti-symmetric sextupole field has some advantages compared to the standard sextupole field, which is widely used in the slow extraction method. One advantage is that it can work at a more distant tune from the resonance, so that it can reduce significantly the intensity variation of the extracted beam which is mainly caused by the ripples of magnet power supplies. Studies by both the Hamiltonian theory and numerical simulations show that the stable region near the half-integer resonance by anti-symmetric sextupole field is much smaller and flatter than the one by standard sextupole field at the third-order resonance. The particles outside the region will be driven out in two possible directions in quite a short transit time but with spiral steps similar to the third-order resonant extraction. By gradually increasing the field strength, the beam can be extracted with intensity more homogeneous than by the usual third-order resonant method, because of both smaller intensity variation and spike in the beginning spill. With the same field strength and tune distance to the resonance, the change in the stable region area due to the working point variation in the case of the anti-symmetric sextupole is about 1/14 of the one for the standard sextupole. Detailed studies including beam dynamic behaviors near other resonances, expression of the field in polynomial expansion, influence of 2-D field error, half-integer stop-band, and resonant slow extraction using a quadrupole field are also presented. © 2016 Elsevier B.V. All rights reserved.

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