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Structured mirror array for two-dimensional collimation of a chromium beam in atom lithography 被引量:2
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作者 张万经 马艳 +4 位作者 李同保 张萍萍 邓晓 陈晟 肖盛炜 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第2期228-231,共4页
Direct-write atom lithography,one of the potential nanofabrication techniques,is restricted by some difficulties in producing optical masks for the deposition of complex structures.In order to make further progress,a ... Direct-write atom lithography,one of the potential nanofabrication techniques,is restricted by some difficulties in producing optical masks for the deposition of complex structures.In order to make further progress,a structured mirror array is developed to transversely collimate the chromium atomic beam in two dimensions.The best collimation is obtained when the laser red detunes by natural line-width of transition 7S3 → 7P40 of the chromium atom.The collimation ratio is 0.45 vertically(in x axis),and it is 0.55 horizontally(in y axis).The theoretical model is also simulated,and success of our structured mirror array is achieved. 展开更多
关键词 atom lithography structured mirror array laser Doppler cooling two-dimensional collimation
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Systematic study on visible light collimation by nanostructured slits in the metal surface 被引量:1
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作者 傅晋欣 华一磊 +3 位作者 陈宇辉 刘荣鹃 李家方 李志远 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第3期460-465,共6页
We present a systematic experimental investigation on visible light collimation by a nanostructured slit flanked with a pair of periodic array of grooves in gold thin film. A wide variety of aspects are considered, su... We present a systematic experimental investigation on visible light collimation by a nanostructured slit flanked with a pair of periodic array of grooves in gold thin film. A wide variety of aspects are considered, such as the polarization state, the transport path of incident light, the groove-groove spacing, the groove width and depth. Our results clearly show that the relationship between the collimation wavelength and the periodicity of the slit-groove structure accords well with the surface plasmon dispersion model proposed by previous researchers. Furthermore, the surface plasmon wave phase retardation effect induced by the surface structure is also verified via the measurement for samples with different groove widths and depths. These results indicate that the detailed geometry of the groove structure has obvious impacts on the collimation effect and the angular distribution of the diffraction light in the subwavelength plasmonic system. 展开更多
关键词 surface plasmon collimation
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Another Collimation Mechanism of Astrophysical Jet
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作者 Yoshinari Minami 《Journal of Earth Science and Engineering》 2017年第2期74-89,共16页
The acceleration mechanism of astrophysical jet and the collimation mechanism narrowing down to a long distance have been examined so far. It is a collimation problem of how to narrow the astrophysical jet narrowly. F... The acceleration mechanism of astrophysical jet and the collimation mechanism narrowing down to a long distance have been examined so far. It is a collimation problem of how to narrow the astrophysical jet narrowly. Further, the model of the astrophysical jet acceleration mechanism is required to solve this collimation problem at the same time as well as its acceleration. At the present time, the magnetic force model (magnetic centrifugal force and magnetic pressure) is regarded as the most dominant theory which solves the two problems of astrophysical jet acceleration and collimation at the same time. In addition to the present astrophysical jet narrow collimation mechanism by magnetic tension (pinch) force, in this article, another collimation mechanism which narrows down an astrophysical jet is newly introduced. That is, since a curvature is generated in the space around the astrophysical jet by magnetic field, a kind of pressure equivalent to the gravitational effect is generated in the direction of the interior of astrophysical jet as well as the pinch force from the outer circumferential surface of the astrophysical jet. 展开更多
关键词 Astrophysical jet accretion disk black hole collimation mechanism acceleration mechanism magnetic field continuum curvature space-time cosmology.
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Enhancement of proton collimation and acceleration by an ultra-intense laser interacting with a cone target followed by a beam collimator
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作者 Yajuan HOU Li WANG +1 位作者 Haibo SANG Baisong XIE 《Plasma Science and Technology》 SCIE EI CAS CSCD 2019年第4期76-84,共9页
A special method is proposed of a laser-induced cavity pressure acceleration scheme for collimating,accelerating and guiding protons,using a single-cone target with a beam collimator through a target normal sheath acc... A special method is proposed of a laser-induced cavity pressure acceleration scheme for collimating,accelerating and guiding protons,using a single-cone target with a beam collimator through a target normal sheath acceleration mechanism.In addition,the problems involved are studied by using two-dimensional particle-in-cell simulations.The results show that the proton beam can be collimated,accelerated and guided effectively through this type of target.Theoretically,a formula is derived for the combined electric field of accelerating protons.Compared with a proton beam without a beam collimator,the proton beam density and cut-off energy of protons in the type II are increased by 3.3 times and 10%respectively.Detailed analysis shows that the enhancement is mainly due to the compact and strong sheath electrostatic field,and that the beam collimator plays a role in focusing energy.In addition,the simulation results show that the divergence angle of the proton beam in type II is less than 1.67 times that of type I.The more prominent point is that the proton number of type II is 2.2 times higher than that of type I.This kind of target has important applications in many fields,such as fast ion ignition in inertial fusion,high energy physics and proton therapy. 展开更多
关键词 single-cone TARGET with BEAM COLLIMATOR TARGET normal SHEATH ACCELERATION mechanism(TNSAM) particle-in-cell(PIC) SHEATH static electric field(SSEF) inertial fusion high energy physics and PROTON therapy PROTON BEAM density cut-off energy of PROTON
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Design of proton beam collimation system for HIAF-BRing
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作者 Wen-Heng Zheng Jian-Cheng Yang +13 位作者 Peng Li Da-Yu Yin Guo-Dong Shen Jie Li Li-Ping Yao Fu-Dong Shi Wei-Ping Chai Li-Jun Mao Wu-yuan Li Geng Wang Bo Yang Cheng Luo Wen-Wen Ge Zhong-Shan Li 《Radiation Detection Technology and Methods》 CSCD 2022年第4期519-529,共11页
Background The Booster Ring is further designed to store and accelerate protons up to 2×1012 particles per pulse in the High-Intensity heavy-ion Accelerator Facility project,which was originally designed to accel... Background The Booster Ring is further designed to store and accelerate protons up to 2×1012 particles per pulse in the High-Intensity heavy-ion Accelerator Facility project,which was originally designed to accelerate high-intensity heavy ion beams.Purpose and Methods To minimize the uncontrolled proton beam halo loss around the ring in operation,a two-stage collimation system is proposed to provide a well-shielded dump for localizing the proton beam halo loss.Results and conclusion In this paper,the simulation is carried out to evaluate the collimation system which shows a 92.93%collimation efficiency.Finally,several factors that affect the collimation efficiency are taken into consideration,including the physical aperture,the offset and rotation errors of the collimators,the closed orbit distortion,as well as the Betatron tunes. 展开更多
关键词 Proton beam Two-stage collimation system ORBIT collimation efficiency
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Beam collimation for CSNS/RCS 被引量:2
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作者 魏涛 吴青彪 李文茜 《Chinese Physics C》 SCIE CAS CSCD 2010年第4期506-511,共6页
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 collimati... 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. 展开更多
关键词 collimation beam loss COLLIMATOR
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Optimization of the collimation system for CSNS/RCS with the robust conjugate direction search algorithm
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作者 纪红飞 焦毅 +3 位作者 黄明阳 许守彦 王娜 王生 《Chinese Physics C》 SCIE CAS CSCD 2016年第9期171-176,共6页
The Robust Conjugate Direction Search(RCDS) method is used to optimize the collimation system for the Rapid Cycling Synchrotron(RCS) of the China Spallation Neutron Source(CSNS). The parameters of secondary coll... The Robust Conjugate Direction Search(RCDS) method is used to optimize the collimation system for the Rapid Cycling Synchrotron(RCS) of the China Spallation Neutron Source(CSNS). The parameters of secondary collimators are optimized for a better performance of the collimation system. To improve the efficiency of the optimization, the Objective Ring Beam Injection and Tracking(ORBIT) parallel module combined with MATLAB parallel computing is used, which can run multiple ORBIT instances simultaneously. This study presents a way to find an optimal parameter combination of the secondary collimators for a machine model in preparation for CSNS/RCS commissioning. 展开更多
关键词 CSNS RCDS collimation system OPTIMIZATION parallel computing
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Study on collimation and shielding of the back-streaming neutrons at the CSNS target
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作者 敬罕涛 唐靖宇 杨征 《Chinese Physics C》 SCIE CAS CSCD 2013年第11期73-78,共6页
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 sche... 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. 展开更多
关键词 spallation target back-streaming neutrons collimation radiation dose rate epoxy coil
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A new method for analyzing the collimation angle of a neutron Soller collimator
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作者 高建波 刘蕴韬 陈东风 《Chinese Physics C》 SCIE CAS CSCD 2016年第1期75-78,共4页
A new method for analyzing the collimation angle of a neutron Soller collimator is described. A Gaus- sian distribution formula is used to define the angular distribution function of the neutron source and the neutron... A new method for analyzing the collimation angle of a neutron Soller collimator is described. A Gaus- sian distribution formula is used to define the angular distribution function of the neutron source and the neutron transmission function of the Soller collimator. A relationship between the FWHM of the collimator rocking curve and the collimation angle is derived. Using this method, some rocking curve experiment results are analyzed. The results show that the new function can be a good theoretical model for fitting the experimental data, especially for the data of two collimators with different collimation angles. 展开更多
关键词 Soller collimator collimation angle neutron beam
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PIC mode simulation of solenoid collimation channel 被引量:2
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作者 肖陈 原有进 +2 位作者 何源 刘勇 夏佳文 《Chinese Physics C》 SCIE CAS CSCD 2010年第8期1136-1139,共4页
A new SSC (Separated Sector Cyclotron)-Linac is being designed to serve as an injector for the SSC at the HIRFL (Heavy Ion Research Facility Lanzhou). The beam intensity at the LEBT (Low Energy Beam Transport) f... A new SSC (Separated Sector Cyclotron)-Linac is being designed to serve as an injector for the SSC at the HIRFL (Heavy Ion Research Facility Lanzhou). The beam intensity at the LEBT (Low Energy Beam Transport) for the heavy ions after the selection is typically low and the space charge effects are inconspicuous. The space charge effects become obvious when the beam current increases to a few hundred microamperes. The emittance growth deriving from the space charge effects may be particularly troublesome for the following linac and cyclotron. An optical system containing three solenoids has been designed for the LEBT to limit the beam emittance and to avoid the unnecessary beam loss in the cyclotron, as well as for the purpose of immunizing the LEBT emittance growth due to the space charge effects. The results of the PIC (Particle- In-Cell) mode simulation illustrate that this channel could limit the beam emittance growth and increase the beam brightness. 展开更多
关键词 PIC SOLENOID LEBT space charge effects COLLIMATOR
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Assessment of Monitor Units and Gamma Pass Rate for 6 MV and Flattening Filter Free (FFF) Beams in Volumetric Modulated Arc Therapy (VMAT)
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作者 Kwame Anokye Amoabeng Anne Beate Langeland Marthinsen +4 位作者 Francis Hasford Samuel Nii Adu Tagoe Evelyn Anaafi Mark Pokoo-Aikins Theresa Bebaaku Dery 《International Journal of Medical Physics, Clinical Engineering and Radiation Oncology》 2023年第1期1-8,共8页
Background: In linear accelerators, the treatment field’s uniform intensity is achieved by including a flattening filter in the beam. However, to produce more conformal dose distributions, contemporary radiotherapy p... Background: In linear accelerators, the treatment field’s uniform intensity is achieved by including a flattening filter in the beam. However, to produce more conformal dose distributions, contemporary radiotherapy practice now frequently uses fluence and aperture modifying techniques, such as volumetric modulated arc therapy. In these circumstances, the flattening filter in the beam manufacturing process is no longer required. It is therefore necessary to compare the monitor units of 6 MV and flattening filter free plans and how it influences the gamma pass rates to determine which is best for treating cervical cancer with pelvic lymph node metastasis. Methods: VMAT plans for fifteen patients with cervical cancer with pathological pelvic lymph node metastasis were included in this study. Each patient had two VMAT plans using conventional 6 MV beam with flattening filter and one with flattening filter free beam (FFF). The VMAT plans were made using two arcs, and then recalculated to give the planned dose distribution to the detectors in a Delta4 phantom. The VMAT plans were irradiated on the Delta4 phantom using an Elekta linear accelerator (6 MV). Results: The mean monitor unit for the 6 MV plans was 506.3 MU and a standard deviation of 48.6 while that of the FFF plans had a mean MU of 701.5 with a standard deviation of 87.6. The total monitor units (MUs) for the FFF plans were significantly greater than the 6 MV plans (p = 6.1 × 10<sup>-5</sup>). Conclusion: Flattening filter free (FFF) plans require more numbers of monitor units in comparison to conventional 6 MV filtered beams for external radiation of cervical cancer with pelvic lymph nodes involvement. 展开更多
关键词 Monitor Units Gamma Pass Rate Flattening Filter Free Multileaf Collimator
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Assessment of Modeling Collimator Designs for Gamma-Ray Transmission of Uranium Oxide Spectrometry Using HPGe Detectors
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作者 Rasha Ali El-Tayebany Hekmat Elbegawy 《World Journal of Engineering and Technology》 2023年第4期663-671,共9页
Many scientific domains use gamma-ray spectrometry, but non-destructive gamma scanning and gamma emission tomography of radioactive fuel in particular. In the experimental setting, a collimator is frequently employed ... Many scientific domains use gamma-ray spectrometry, but non-destructive gamma scanning and gamma emission tomography of radioactive fuel in particular. In the experimental setting, a collimator is frequently employed to focus on a particular location of interest in the fuel. Predictive models for the transmitted gamma-ray intensity through the collimator are required for both the optimization of instrument design and the planning of measurement campaigns. Gamma-ray transport accuracy is frequently predicted using Monte Carlo radiation transport methods, but using these tools in low-efficiency experimental setups is challenging due to the lengthy computation times needed. This study focused on the full-energy peak intensity that was transmitted through several collimator designs, including rectangle and cylinder. The rate of photons arriving at a detector on the other side of the collimator was calculated for anisotropic source of SNM (U<sub>3</sub>O<sub>8</sub>). Some geometrical assumptions that depended on the source-to-collimator distance and collimator dimensions (length, radius or length, height, and width) were applied to achieve precise findings. 展开更多
关键词 Monte Carlo High Purity Germanium (HPGe) COLLIMATOR URANIUM
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Post-linac beam collimation study of SHINE
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作者 Bingyang Yan He Liu +3 位作者 Si Chen Haixiao Deng Qisheng Tang Bo Zhang 《Radiation Detection Technology and Methods》 2024年第2期1286-1297,共12页
Purpose X-ray free-electron laser facilities require high-repetition and high-energy electron beams,which makes the radiation safety become an important issue due to beam loss.Beam collimation is used to protect the u... Purpose X-ray free-electron laser facilities require high-repetition and high-energy electron beams,which makes the radiation safety become an important issue due to beam loss.Beam collimation is used to protect the undulator and other devices by removing the beam halo in operation,as well as absorbing the off-axis beam in the case of machine failure.Method In this paper,the beam collimation system in the switchyard of the SHINE is presented.Results and conclusion Tracking with an expanded initial beam distribution,the efficiency of the collimation system is shown,and the detailed collimation performance is simulated to evaluate the available limitation from the acceptance of the undulator.Moreover,the accidental beam loss and wakefield effects are also considered to ensure the reliability of the collimation. 展开更多
关键词 Free electron laser Beam switchyard Beam collimation Wakefield simulation
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瓦里安21EX直线加速器多叶准直器维护与维修 被引量:7
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作者 王艳菊 高峰 +1 位作者 房彤 谭春荣 《医疗卫生装备》 CAS 2015年第5期150-152,共3页
0引言 配备多叶准直器(mulli-leaf collimator,MLC)系统的直线加速器能使照射野最大限度地接近肿瘤形状,从而达到最大限度地杀死肿瘤细胞,同时最小程度影响正常组织的目的[1]。由于MLC比挡铅的操作方法更简单快速[2],目前配有MLC的... 0引言 配备多叶准直器(mulli-leaf collimator,MLC)系统的直线加速器能使照射野最大限度地接近肿瘤形状,从而达到最大限度地杀死肿瘤细胞,同时最小程度影响正常组织的目的[1]。由于MLC比挡铅的操作方法更简单快速[2],目前配有MLC的直线加速器在全国各地的放疗科应用越来越广泛[3]。因多叶准直器被安装在医用电子直线加速器的照射机头上,所以部件受辐射比较严重, 展开更多
关键词 医用电子直线加速器 多叶准直器 COLLIMATOR 维修 维护 肿瘤形状 肿瘤细胞 正常组织
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医科达Precise医用直线加速器多叶准直器(MLC)维修2例 被引量:6
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作者 陈建平 张富利 《医疗卫生装备》 CAS 2009年第9期123-123,共1页
随着计算机技术的飞速发展和加速器设备的改进,三维适形放射治疗逐渐得到普及,使得靶区和邻近的危及器官的剂量分布有了较大的改善,最大限度地将照射剂量集中到病变(靶区)内,杀灭肿瘤细胞,使周围正常组织和器官减少或免受照射,从而提... 随着计算机技术的飞速发展和加速器设备的改进,三维适形放射治疗逐渐得到普及,使得靶区和邻近的危及器官的剂量分布有了较大的改善,最大限度地将照射剂量集中到病变(靶区)内,杀灭肿瘤细胞,使周围正常组织和器官减少或免受照射,从而提高了放射治疗的治疗增益比[1]。采用多叶准直器(multileaf collimator,MLC)的调强适形放射治疗(intensity modulated radiation therapy.IMRT)是当前放疗的主流技术之一^[2]。 展开更多
关键词 多叶准直器 医用直线加速器 三维适形放射治疗 COLLIMATOR 调强适形放射治疗 维修 医科 照射剂量
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医科达Synergy直线加速器光学系统故障分析与维修 被引量:10
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作者 魏天安 高艺芬 陈大朝 《中国医学装备》 2017年第1期125-126,共2页
采用多叶准直器(multileaf collimator,MLC)的调强适形放射治疗(intensity modulated radiation therapy,IMRT)是当前放射治疗的主流技术之一,其通过光学监视系统来影响多叶准直器的控制,最大精度将照射剂量集中到病变内,移除肿瘤细... 采用多叶准直器(multileaf collimator,MLC)的调强适形放射治疗(intensity modulated radiation therapy,IMRT)是当前放射治疗的主流技术之一,其通过光学监视系统来影响多叶准直器的控制,最大精度将照射剂量集中到病变内,移除肿瘤细胞,且周围正常组织和器官减少或免受照射。 展开更多
关键词 光学系统 直线加速器 故障分析 调强适形放射治疗 COLLIMATOR 多叶准直器 维修 医科
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Manipulation and optimization of electron transport by nanopore array targets 被引量:3
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作者 Yue YANG Boyuan LI +11 位作者 Yuchi WU Bin ZHU Bo ZHANG Zhimeng ZHANG Minghai YU Feng LU Kainan ZHOU Lianqiang SHAN Lihua CAO Zongqing ZHAO Weimin ZHOU Yuqiu GU 《Plasma Science and Technology》 SCIE EI CAS CSCD 2021年第1期8-14,共7页
The transport of sub-picosecond laser-driven fast electrons in nanopore array targets is studied.Attributed to the generation of micro-structured magnetic fields,most fast electron beams are proven to be effectively g... The transport of sub-picosecond laser-driven fast electrons in nanopore array targets is studied.Attributed to the generation of micro-structured magnetic fields,most fast electron beams are proven to be effectively guided and restricted during the propagation.Different transport patterns of fast electrons in the targets are observed in experiments and reproduced by particle-in-cell simulations,representing two components:initially collimated low-energy electrons in the center and high-energy scattering electrons turning into surrounding annular beams.The critical energy for confined electrons is deduced theoretically.The electron guidance and confinement by the nano-structured targets offer a technological approach to manipulate and optimize the fast electron transport by properly modulating pulse parameters and target design,showing great potential in many applications including ion acceleration,microfocus x-ray sources and inertial confinement fusion. 展开更多
关键词 nanopore array laser-driven electrons fast electron transport electron collimation
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CT机Collimator详析 被引量:1
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作者 杨舒波 《医疗装备》 2005年第6期53-53,共1页
X -CT的品牌、型号较多,但不管是什么厂家什么型号的CT ,其Collimator的结构都是大同小异,本文将详细剖析单层CT机的Collimator的结构,讨论一些常见故障,并提出相应解决方法。
关键词 COLLIMATOR CT机 X-CT 常见故障 解决方法 型号 结构
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Two-phase flow component fraction measurement using gamma-ray attenuation technique
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作者 Mohsen Sharifzadeh Hosein Khalafi +1 位作者 Hosein Afarideh Ehsanallah Noori 《Nuclear Science and Techniques》 SCIE CAS CSCD 2017年第6期196-202,共7页
Multiphase flow meters as the potential alternatives to separation and metering techniques have been in rapid development since 1980 s.Before its field operation,the instrument should be calibrated in a standard test-... Multiphase flow meters as the potential alternatives to separation and metering techniques have been in rapid development since 1980 s.Before its field operation,the instrument should be calibrated in a standard test-facility.In spite of the known medium and large scale facilities all over the world,we developed a laboratory scale instrument for component fraction measurements.It has a two-phase flow homogenizer loop with the clamp-on potential of the meters to provide a regime independent measurement.It is capable of delivering a complete homogenization by γ-ray densitometer.With an error of±5%in component fraction measurements,this instrument is appropriate for testing and calibrating other meters. 展开更多
关键词 COMPONENT FRACTION MEASUREMENT Homogenization MATLAB-Based algorithm Pencilbeam collimation GAMMA-RAY ATTENUATION
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Manipulation of extraordinary acoustic transmission by a tunable bull's eye structure
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作者 王继伟 程营 刘晓峻 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第5期27-31,共5页
Extraordinary acoustic transmission (EAT) has been investigated in a tunable bull's eye structure. We demonstrate that the transmission coefficient of acoustic waves can be modulated by a grating structure. When th... Extraordinary acoustic transmission (EAT) has been investigated in a tunable bull's eye structure. We demonstrate that the transmission coefficient of acoustic waves can be modulated by a grating structure. When the grating is located at a distance of 0.5 mm from the base plate, the acoustic transmission shows an 8.77-fold enhancement compared to that by using a traditional bull's eye structure. When the distance increases to 1.5 mm, the transmission approaches zero, indicating a total reflection. Thus, we can make an efficient modulation of acoustic transmission from 0 to 877%. The EAT effects have been ascribed to the coupling of structure-induced resonance with the diffractive wave and the waveguide modes, as well as the Fabry-Perot resonances. As a potential application, the modulation of far-field collimation is illustrated in the proposed bull's eye structure. 展开更多
关键词 extraordinary acoustic transmission acoustic grating transmission modulation sound collimation
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