检索结果-南通市图书馆

Beam collimation for CSNS/RCS

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2010年第4期34卷 506-511页

作者：魏涛吴青彪李文茜 Institute of High Energy Physics CAS Department of Physics Engineering Tsinghua University

The current design of the CSNS/RCS beam collimation system consists of a two-stage betatron collimation and a single momentum collimator. This paper summarizes various aspects of collimator design, including collimation principle and layout, material choice and collimator mechanical structure, etc. At last, radiation and thermal analysis are carried out to illustrate the feasibility of the current beam collimation scheme.

关键词： collimation beam loss collimator

Study on collimation and shielding of the back-streaming neutrons at the CSNS target

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2013年第11期37卷 73-78页

作者：敬罕涛唐靖宇杨征 Institute of High Energy Physics Chinese Academy of Sciences

The back-streaming neutrons from the spallation target at CSNS are very intense, and can pose serious damage problems for the devices in the accelerator-target interface region. To tackle the problems, a possible scheme for this region was studied, namely a specially designed optics for the proton beam line produces two beam waists, and two collimators are placed at the two waist positions to maximize the collimation effect of the back-streaming neutrons. Detailed Monte Carlo simulations with the beams in the two different CSNS phases show the effectiveness of the collimation system, and the radiation dose rate decreases largely in the interface section. This can ensure the use of epoxy coils for the last magnets and other devices in the beam transport line with reasonable lifetimes, e.g., thirty years. The design philosophy for such an accelerator-target interface region can also be applicable to other high-power proton beam applications.

关键词： spallation target back-streaming neutrons collimation radiation dose rate epoxy coil

Two-phase flow component fraction measurement using gamma-ray attenuation technique

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2017年第6期28卷 196-202页

作者： Mohsen Sharifzadeh Hosein Khalafi Hosein Afarideh Ehsanallah Noori Radiation Application Research School Nuclear Science and Technology Research Institute Department of Energy Engineering and Physics AmirKabir University of Technology Nuclear Science and Technology Research Institute Plasma Research School Nuclear Science and Technology Research Institute

Multiphase flow meters as the potential alternatives to separation and metering techniques have been in rapid development since 1980 *** its field operation,the instrument should be calibrated in a standard *** spite of the known medium and large scale facilities all over the world,we developed a laboratory scale instrument for component fraction *** has a two-phase flow homogenizer loop with the clamp-on potential of the meters to provide a regime independent *** is capable of delivering a complete homogenization by γ-ray *** an error of±5%in component fraction measurements,this instrument is appropriate for testing and calibrating other meters.

关键词： Component fraction measurement Homogenization MATLAB-Based algorithm Pencilbeam collimation Gamma-ray attenuation

Design and construction of the MEBT1 for CADS injector scheme Ⅱ

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2015年第10期39卷 121-126页

作者：贾欢何源原有进宋明涛皇世春张翔袁辰彰牛海华张鹏武军霞张雍康新才罗成 Institute of Modern Physics Chinese Academy of Sciences University of Chinese Academy of Sciences

A Medium Energy Beam Transport line 1 （MEBT1） has been designed for Injector Scheme II of the China, ADS project. To match the beam from RFQ to Superconducting （SC） Half Wave Resonator （HWR） sections with emittance preservation, the MEBT1 has been designed to be mechanically compact. Working at 162.5 MHz, the MEBT1 transports a 10 mA, 2.1 MeV proton beam using seven quadrupoles and two bunching cavities within 2.7 meters. Three collimators are placed between every two adjacent quadrupoles to collimate the beam halo. Design and construction of the MEBT1 are presented in this paper.

关键词： MEBT CADS match collimation QWR

Simulation of loss of uranium ions due to charge changing processes in the CSRm ring

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2015年第4期39卷 87-90页

作者：郑文亨杨建成李朋李钟汕商鹏曲国峰葛文文汤梅堂沙小平 Institute of Modern Physics Chinese Academy of Sciences University of Chinese Academy of Sciences

Significant beam loss caused by the charge exchange processes and ion impact-induced outgassing may restrict the maximum number of accelerated heavy ions during the high intensity operation of an accelerator. In order to control beam loss due to charge exchange processes and confine the generated desorption gas, tracking of the beam loss distribution and installation of absorber blocks with low-desorption rate material at appropriate locations in the main Cooler Storage Ring （CSRm） at the Institute of Modern Physics, Lanzhou, will be performed. The loss simulation of uranium ions with electron-loss is presented in this report and the conclusion is that most charge changed particles are lost in the second dipole of the super-period structure. The calculation of the collimation efficiency of the CSRm ring will be continued in the future.

关键词： beam loss charge exchange CSRm collimation

Particle-in-cell mode beam dynamics simulation of the low energy beam transport for the SSC-linac injector

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2011年第5期35卷 500-504页

作者： XIAO Chen HE Yuan YUAN You-Jin YAO Qing-Gao WANG Zhi-Jun CHANG Wei LIU Yong XIA Jia-Wen Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China Graduate University of Chinese Academy of Sciences Beijing 100049 China The School of Nuclear Science and Technology Lanzhou University Lanzhou 730000 China

A new SSC-linac system （injector into separated sector cyclotron） is being designed in the HIRFL （heavy ion research facility of Lanzhou）. As part of SSC-Linac, the LEBT （low energy beam transport） consists of seven solenoids, four quadrupoles, a bending magnet and an extra multi-harmonic buncher. The total length of this segment is about 7 meters. The beam dynamics in this LEBT has been studied using three-dimensional PIC （particle-in-cell） code BEAMPATH. The simulation results show that the continuous beam from the ion source is first well analyzed by a charge-to-mass selection system, and the beam of the selected charge-to-mass ratio is then efficiently pre-bunched by a multi-harmonic buncher and optimally matched into the RFQ （radio frequency quadrupole） for further acceleration. The principles and effects of the solenoid collimation channel are discussed, and it could limit the beam emittance by changing the aperture size.

关键词： SSC-linac LEBT PIC mode optimal injection collimation

Does Resampled Image Data Offer Quantitative Image Quality Benefit for Pediatric CT?

在线全文

学校读者我要写书评

暂无评论

Journal of Biomedical Science and Engineering 2014年第6期7卷 343-350页

作者： Nancy L. Ford Angjelina Protik Paul Babyn Karen Thomas Ryerson University Toronto Canada The Hospital for Sick Children and University of Toronto Toronto Canada University of British Columbia Vancouver Canada University of Saskatchewan Saskatoon Canada

Acquiring CT images with thin slices can improve resolution and detectability, but cause an increase in the image noise. To compensate for the additional image noise, the kVp or mA can be increased, which carries a dose penalty to the patient. We investigate the image quality achieved in MPR images reformatted from different slice thicknesses 0.625 mm and 5 mm, to determine if a thicker slice could be resampled to smaller thickness with minimal loss of image information. Catphan?600 phantom was imaged using selected kVp/mA settings (80 kVp/250 mA, 100 kVp/ 150 mA and 120 kVp/200 mA) to generate slices with thicknesses of 0.625 mm and 5 mm using a GE Discovery HD750 64-slice CT scanner to investigate the impact of the acquisition slice thickness on the overall image quality in MPRs. Measurements of image noise, uniformity, contrast-to-noise ratio (CNR), low contrast detectability and limiting spatial resolution were performed on axial and coronal multiplanar reformatted images (MPRs). Increased noise, reduced contrast-to-noise ratio, and improved limiting spatial resolution and low contrast detection were observed in 2 mm coronal MPRs generated with 0.625 mm thin slices when compared to the MPRs from 5 mm thick slices. If the 2 mm coronal MPRs acquired with 5 mm slices are resampled to 0.6 mm slice thickness, the reductions in limiting resolution and low contrast detection are compensated, although with reduced uniformity and increased image noise. Thick slice image acquisitions yield better CNR and less noise in the images, whereas thin slices exhibited improved spatial resolution and low contrast detectability. Retrospectively resampling into thinner slices before obtaining the coronal MPRs provided a balance between image smoothness and identifying fine image detail. Which approach provides the optimal image quality may also depend on the imaging task, size and composition of the features of interest, and radiologist preference.

关键词： Paediatric CT Image Quality Multiplanar Reformats (MPR) collimation