检索结果-南通市图书馆

A curve-based material recognition method in MeV dual-energy X-ray imaging system

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2016年第1期27卷 13-20页

作者： Zhi-Qiang Chen Tiao Zhao Liang Li Department of Engineering Physics Tsinghua University Key laboratory of particle and radiation imaging (TsinghuaUniversity) Ministry of Education

High-energy dual-energy X-ray digital radiography imaging is mainly used in the material recognition of cargo inspection. We introduce the development history and principle of the technology and describe the data process flow of our system. The system corrects original data to get a dual-energy transparence image. Material categories of all points in the image are identified by the classification curve,which is related to the X-ray energy spectrum. For the calibration of classification curve, our strategy involves a basic curve calibration and a real-time correction devoted to enhancing the classification accuracy. Image segmentation and denoising methods are applied to smooth the image. The image contains more information after colorization. Some results show that our methods achieve the desired effect.

关键词： X射线成像系统校准曲线材料识别识别方法数据处理流程透明图像分类精度实时校正

An industrial CT system for monitoring a running aero-engine

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2014年第6期25卷 24-30页

作者：常铭肖永顺陈志强 Department of Engineering Physics Tsinghua University Key laboratory of particle & radiation imaging Tsinghua University

In order to improve aerodynamic performance and efficiency, monitoring the geometry and position information of the internal structure with the aero-engine under various operational statuses is an important task. In this paper, a novel design of industrial computed tomography(ICT) system with a linac as X-ray source is proposed to complete the task. The major advantage of the proposed system is that it can provide visualized images of internal structures of the running aero-engine without physical disturbance, which makes it possible to extract the accurate geometry information. The main idea behind this design is to measure the projection data from various views for reconstructions making use of the rotations of the aero-engine blades, instead of the mechanical rotations in the conventional ICT system. However, due to high speed rotation of the aero-engine blades,the system faces more challenges than conventional ICT systems both in data acquisitions and reconstruction algorithms. The challenges and corresponding solutions are presented in this paper. In conclusion, the proposed ICT system provides a powerful tool for monitoring the running aero-engines.

关键词：航空发动机叶片工业CT系统运行工业计算机断层扫描空气动力性能信息通信系统内部结构线性加速器

Measurement of avalanche size and position resolution of RPCs with different surface resistivities of the high voltage provider

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2010年第5期34卷 565-570页

作者：岳骞李元景叶瑾程建平王义李金吴昱城 Department of Engineering Physics Tsinghua University Key laboratory of particle & radiation imaging Tsinghua University

The effects of surface resistivity of the high voltage provider on the space dispersion of the induced charge of a prototype Resistive Plate Chamber （RPC） have been studied experimentally and theoretically. The results of both experiment and theory agree and confirm that a two-Gaussian function can be used to fit the dispersion of the induced charge of the RPC. It is shown that the Gaussian function with the narrower width is mainly due to the expansion of the avalanche charge in the gas gap of the RPC, and the Gaussian function with the larger width is due to the charge dispersion when it passes through the resistive carbon film. This will be useful in the RPC design when one wants to make an RPC with high position resolution.

关键词： RPC surface resistivity avalanche size position resolution

Characterization of a broad-energy germanium detector for its use in CJPL

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2017年第1期28卷 42-48页

作者： Zhi Zeng Yu-Hao Mi Ming Zeng Hao Ma Qian Yue Jian-Ping Cheng Jun-Li Li Rui Qiu Hui Zhang Key laboratory of particle and radiation imaging (Ministry of Education) and Department of Engineering Physics Tsinghua University Beijing 100084 China

The broad-energy germanium(BEGe)detector,with the ability of background discrimination using pulse shape discrimination,is a competitive candidate for neutrinoless double beta decay(ovββ)*** this paper,we report our measurements of key parameters for detector modeling in a commercial p-type BEGe ***-like sources are used to investigate energy resolution and linearity of the detector.A cylindrical volume source is used for efficiency *** an assembled device for source positioning and a collimated ^(133)Ba source,the detector is scanned to check its active *** an^(241)Am point-like source,the dead layer thicknesses is measured at about 0.17 mm on the front and 1.18 mm on the *** detector characterization is of importance for BEGe detectors to be used in the ovββ experiments at China JinPing underground laboratory(CJPL).

关键词： BEGe Characterization Dead layer 0mbb CJPL

Twin image removal in X-ray fluorescence holography with two energies

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2008年第12期32卷 1016-1020页

作者：陈淼鑫李政 Key laboratory of particle & radiation imaging (Tsinghua University) Ministry of EducationDepartment of Engineering Physics Tsinghua University

In the last decade, X-ray fluorescence holography has been developed for the study of 3D atomic arrangements in solids. However, it encounters the twin image problem which may disturb the reconstructed atomic images. In this paper, the formation of twin image is discussed and we propose a modified two-energy algorithm to remove the twin image. The simulation shows that the method is valid and more efficient than the multiple-energy algorithm proposed by Barton.

关键词： X-ray holography twin image

Characteristics of terahertz coherent transition radiation generated from picosecond ultrashort electron bunches

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2010年第6期19卷 221-230页

作者：刘文鑫唐传祥黄文会 Department of Engineering Physics Tsinghua University Key laboratory of particle & radiation imaging (Tsinghua University) Ministry of EducationTsinghua University Key laboratory of High Energy radiation imaging Fundamental Science for National Defense Tsinghua University

This paper presents a method of generating terahertz （THz） coherent transition radiation （CTR） from picosecond ultrashort electron bunches including single and train bunches, which are produced by a photocathode radio frequency gun. The radiation characteristics of THz CTR including formation factor and energy spectrum are analysed in detail. With the help of a 2-dimensional particle-in-cell simulation, the radiation characteristics including power, energy and magnetic field are analysed. The results show that the radiation frequency can be adjusted by tuning the repetition frequency of the train bunch and the energy can be enhanced with the train bunches.

关键词： coherent transition radiation photocathode radio-frequency gun ultrashort electron bunches particle-in-cell

TW Laser system for Thomson scattering X-ray light source at Tsinghua University

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2009年第S2期33卷 154-156页

作者：颜立新杜应超杜强李任恺华剑飞黄文会唐传祥 Accelerator laboratory Department of Engineering Physics Key laboratory of particle & radiation imaging Ministry of Education Tsinghua University

A TW (Tera Watt) laser system based on Ti:sapphire mainly for the Tsinghua Thomson scattering X-ray light source (TTX) is being built. Both UV (ultraviolet) laser pulse for driving the photocathode radiofrequency (RF) gun and the IR (infrared) laser pulse as the electron-beam-scattered-light are provided by the system. Efforts have also been made in laser pulse shaping and laser beam transport to optimize the high-brightness electron beam production by the photocathode RF gun.

关键词： Thomson scattering TW laser photocathode RF gun

A prototype of a high rating MRPC

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2009年第5期33卷 374-377页

作者：王义王景波颜强李元景程建平岳骞李金 Department of Engineering Physics Tsinghua University Key Laboratory of Particle & Radiation ImagingMinistry of Education

Six-gap resistive plate chamber （MRPC） prototypes with semiconductive glass electrodes （bulk resistivity ～ 10^10Ω·cm） were studied for suitability in time-of-flight （TOF） applications at high rates. These studies were performed using a continuous electron beam of 800 MeV at IHEP and an X-ray machine. Time resolutions of about 100 ps and efficiencies larger than 90% were obtained for flux densities up to 28 kHz/cm^2.

关键词： MRPC bulk resistivity high rate time resolution

Simulation for signal charge transfer of charge coupled devices

在线全文

学校读者我要写书评

暂无评论

Journal of Semiconductors 2009年第12期30卷 42-49页

作者：王祖军刘以农陈伟唐本奇肖志刚黄绍艳刘敏波张勇 Department of Engineering Physics Key Laboratory of Particle & Radiation Imaging of Ministry of EducationTsinghua University Northwest Institute of Nuclear Technology

Physical device models and numerical processing methods are presented to simulate a linear buried channel charge coupled devices （CCDs）. The dynamic transfer process of CCD is carried out by a three-phase clock pulse driver. By using the semiconductor device simulation software MEDICI, dynamic transfer pictures of signal charges cells, electron concentration and electrostatic potential are presented. The key parameters of CCD such as charge transfer efficiency （CTE） and dark electrons are numerically simulated. The simulation results agree with the theoretic and experimental results.

关键词： CCD CTE dark signal numerical simulation MEDICI