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热成像系统的空间和温度分辨极限 总被引:1,自引:0,他引:1
从辐射传递理论出发,运用空间分辨和温度分辨的概念,分析了热成像系统的对给目标背景的极限分辨距离和望远镜头的选用准则,最后对给定系统进行了计算。 相似文献
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超快电子衍射技术是研究物质瞬态结构变化及超快结构动力学的有效手段.研制了国内第一套同时具有超快时间分辨及超高空间分辨能力的超快电子衍射系统,并研究了在该超快电子衍射系统上实现超快时间分辨及超高空间分辨能力的技术手段及其优化方法.实验结果表明:经过优化后该系统可以具有优于500 fs的时间分辨能力,其空间分辨能力达到0.04%的衍射峰位置变化,对应的晶面变化为0.0005?.该系统可以为实时测量超快光脉冲激发的物质瞬态结构变化,特别是为研究晶体材料的超快动力学行为提供了强有力的实验工具.
关键词:
超快电子衍射
空间分辨
时间分辨 相似文献
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一、原理平面透射光栅的色分辨本领的表式为λ/△λ=jN (1)j是干涉级、N是光栅受照面上的实际缝数。为了验证(1)式,可用光波波长λ及波长差△λ都已知的光源照射光栅,使光栅对波长差为△λ的两谱线处于恰能分辨状态,然后在分光计上测定在这种状态下j和N的值.把实测到的jN值与已知的λ/△λ进行比较,以验证(1)式。 相似文献
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基于Monte Carlo方法对HIRFL CSRm上的TPC的性能进行了模拟.研究了磁场、读出电极几何尺寸、灵敏丝距以及读出电极平面与灵敏丝平面之间的距离等参数对TPC性能的影响,给出了TPC的一些最佳设计参数. Based on Monte-Carlo method the time projection chamben s (TPC s) performance at HIRFL-CSRm has been simulated. We have already studied the effect of magnetic field, wire space, the size of readout pad and the distance between the pad plane and the wire plane on the performance of TPC. At the same time some important results are given for designing TPC. 相似文献
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描述了一种用于中能重离子核反应实验研究的大动态范围双维位置灵敏多叠层探测系统.该探测系统由纵向电场气体电离室(IC)、大面积双维位置灵敏穿透型Si探测器(PSSD)、大面积Si光敏二极管(SPD)和用光二极管读出的16单元CsI(Tl)闪烁体探测器阵列组成.用a放射源Am(5.486MeV)测得的IC、PSSD的能量分辨率分别为3%和2.6%.在25MeV/u 40Ar诱发的核反应中,探测到的a粒子的能量动态范围为2—130MeV,此探测系统清楚地分辨出Z=2到Z=21的元素,对Z=18的Z分辨本领Z/△Z≈44.5,位置分辨为0.86±0.03mm(FWHM). 相似文献
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介绍了基于球面弯晶的X射线高分辨单色背光成像技术。通过对球面弯晶背光成像系统的分析,获得成像关键性能参数随成像系统设计参数变化的关系,设计了应用于神光Ⅱ激光装置的单色背光成像系统。利用石英球面弯晶,采用Mg的类H共振发射线以及利用云母球面弯晶,采用Mo连续谱中3.14 keV能点进行背光实验,获得了内爆靶丸的单色投影图像,空间分辨在较大范围内好于5 m。这种成像技术在现阶段惯性约束聚变(ICF)实验研究中能够发挥许多重要的作用,特别是对内爆靶丸压缩流线的测量和流体力学不稳定性的诊断。 相似文献
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Constraining the cosmic ray propagation halo thickness using Fermi-LAT observations of high-latitude clouds
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Yuhua Yao Bing-Qiang Qiao Wei Liu Qiang Yuan Hong-Bo Hu Xiao-Jun Bi Chao-Wen Yang Yi-Qing Guo 《中国物理C(英文版)》2021,45(10):105104-105104-8
The diffusive halo is a basic characteristic of cosmic ray (CR) propagation and can advance our understanding of many CR-related phenomena and indirect dark matter. The method used to derive the halo size often has degeneracy problems and is thus affected by large uncertainties. The diffuse \begin{document}$\rm\gamma$\end{document} ![]()
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rays from high-latitude clouds might shed light on the halo size independently. Because predictions using the spatially dependent propagation (SDP) model have better agreement with the observed CRs than those of the conventional propagation model, in this work, we investigated halo thickness based on the SDP model using Fermi-LAT \begin{document}$\rm\gamma$\end{document} ![]()
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-ray observations of high- and intermediate-velocity clouds. We found that to avoid exceeding the relative \begin{document}$\gamma$\end{document} ![]()
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-ray emissivity in high-latitude clouds, the halo thickness should be in the range of 3.3-9 kpc. Moreover, the spatial morphology of \begin{document}$\rm\gamma$\end{document} ![]()
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-rays estimated based on the SDP model for different values of the halo thickness are distinctive, which provides us with a tool to determine the halo size. This newly developed model can be tested and tuned using multi-wavelength observations in future studies. 相似文献
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小型宇宙射线探测仪的模拟和测量 总被引:1,自引:0,他引:1
介绍了一款小型宇宙射线探测仪。该仪器具有宇宙射线科普演示功能,主要用于实时测量μ子射线并显示计数,以及长时间尺度下(年)稳定地对不同角度的次级宇宙线通量进行监控记录。简要地展示了探测器的硬件构造和探测效率的模拟计算。探测仪单个探测器的探测效率为93.1%,两个探测器符合测量的探测效率为86.6%。根据探测器的计数率以及模拟计算的探测效率,估计了次级宇宙射线垂直地面方向的通量,为J=29±3 m-2 sr-1 s-1。另外,利用该宇宙射线探测仪,测量了兰州市区的次级宇宙射线的天顶角分布。其结果很好地满足I(θ)=IH+I0 cosα θ经验公式,其中的角度依赖参数α=2.42±0.52。A small cosmic ray device is introduced in this paper.It has the demonstration function for popularization of science,and can be used mainly to display the μ counts in a real-time measurement,and to monitor the secondary cosmic ray flux at different angles in a very long time scale (years).We briefly show the hardware of the device and the detecting efficiency calculation by simulation.The detecting efficiency for one detector of the device is 93.1%,and the detecting efficiency is 86.6% for the coincidence measurement of two detectors.Based on the count rate by the detector and the simulated efficiency,the secondary cosmic ray flux perpendicular to the ground surface is measured,which is J=29±3 m-2sr-1 s-1.Moreover,with an application of the device,we measured the angular distribution of the secondary cosmic ray rate in Lanzhou City.The resulting angular distribution agrees well with the empirical formula as I(θ)=IH+I0 cosα θ,in which the parameter for the angle-dependence is α=2.42±0.53. 相似文献
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Gema Martínez‐Criado Rémi Tucoulou Peter Cloetens Pierre Bleuet Sylvain Bohic Jean Cauzid Isabelle Kieffer Ewelina Kosior Sylvain Labouré Sylvain Petitgirard Alexander Rack Juan Angel Sans Jaime Segura‐Ruiz Heikki Suhonen Jean Susini Julie Villanova 《Journal of synchrotron radiation》2012,19(1):10-18
The ESRF synchrotron beamline ID22, dedicated to hard X‐ray microanalysis and consisting of the combination of X‐ray fluorescence, X‐ray absorption spectroscopy, diffraction and 2D/3D X‐ray imaging techniques, is one of the most versatile instruments in hard X‐ray microscopy science. This paper describes the present beamline characteristics, recent technical developments, as well as a few scientific examples from recent years of the beamline operation. The upgrade plans to adapt the beamline to the growing needs of the user community are briefly discussed. 相似文献
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A. Rack T. Weitkamp M. Riotte D. Grigoriev T. Rack L. Helfen T. Baumbach R. Dietsch T. Holz M. Kr?mer F. Siewert M. Meduňa P. Cloetens E. Ziegler 《Journal of synchrotron radiation》2010,17(4):496-510
A systematic study is presented in which multilayers of different composition (W/Si, Mo/Si, Pd/B4C), periodicity (from 2.5 to 5.5 nm) and number of layers have been characterized. In particular, the intrinsic quality (roughness and reflectivity) as well as the performance (homogeneity and coherence of the outgoing beam) as a monochromator for synchrotron radiation hard X‐ray micro‐imaging are investigated. The results indicate that the material composition is the dominating factor for the performance. By helping scientists and engineers specify the design parameters of multilayer monochromators, these results can contribute to a better exploitation of the advantages of multilayer monochromators over crystal‐based devices; i.e. larger spectral bandwidth and high photon flux density, which are particularly useful for synchrotron‐based micro‐radiography and ‐tomography. 相似文献
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X‐ray fluorescence induced by standing waves in the grazing‐incidence and grazing‐exit modes: study of the Mg–Co–Zr system
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Yuchun Tu Yanyan Yuan Karine Le Guen Jean‐Michel André Jingtao Zhu Zhanshan Wang Françoise Bridou Angelo Giglia Philippe Jonnard 《Journal of synchrotron radiation》2015,22(6):1419-1425
The characterization of Mg–Co–Zr tri‐layer stacks using X‐ray fluorescence induced by X‐ray standing waves, in both the grazing‐incidence (GI) and the grazing‐exit (GE) modes, is presented. The introduction of a slit in the direction of the detector improves the angular resolution by a factor of two and significantly improves the sensitivity of the technique for the chemical characterization of the buried interfaces. By observing the intensity variations of the Mg Kα and Co Lα characteristic emissions as a function of the incident (GI mode) or detection (GE mode) angle, it is shown that the interfaces of the Si/[Mg/Co/Zr]×30 multilayer are abrupt, whereas in the Si/[Mg/Zr/Co]×30 multilayer a strong intermixing occurs at the Co‐on‐Zr interfaces. An explanation of this opposite behavior of the Co‐on‐Zr and Zr‐on‐Co interfaces is given by the calculation of the mixing enthalpies of the Co–Mg, Co–Zr and Mg–Zr systems, which shows that the Co–Zr system presents a negative value and the other two systems present positive values. Together with the difference of the surface free energies of Zr and Co, this leads to the Mg/Zr/Co system being considered as a Mg/CoxZry bi‐layer stack, with x/y estimated around 3.5. 相似文献
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The high/low amplitude anisotropic wave-train events (HAE/LAE) in cosmic-ray intensity have been investigated during the period 1991-94, using the neutron monitor data for different latitudes. In all, 16 HAE and 13 LAE cases have been studied. An inter-comparison of the first three harmonics during these events has been made so as to understand the basic reason causing the occurrence of these types of events. It has been observed that the phase of diurnal anisotropy shifts towards earlier hours for HAEs; similarly, it shifts towards earlier hour as compared to 18-Hr direction for LAEs. For semi-diurnal anisotropy phase remains statistically the same for both HAE as well as for LAE. Further in case of tri-diurnal anisotropy phase is evenly distributed for both types of events. The interplanetary magnetic field and solar-wind plasma parameters during these events are also investigated. It has been also observed that HAE/LAEs are weakly dependent on solar-wind velocity. 相似文献
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Jean‐Louis Hazemann Olivier Proux Vivian Nassif Hervé Palancher Eric Lahera Cécile Da Silva Aurélien Braillard Denis Testemale Marie‐Ange Diot Isabelle Alliot William Del Net Alain Manceau Frédéric Gélébart Marc Morand Quentin Dermigny Abhay Shukla 《Journal of synchrotron radiation》2009,16(2):283-292
A bent‐crystal spectrometer based on the Rowland circle geometry has been installed and tested on the BM30b/FAME beamline at the European Synchrotron Radiation Facility to improve its performances. The energy resolution of the spectrometer allows different kinds of measurements to be performed, including X‐ray absorption spectroscopy, resonant inelastic X‐ray scattering and X‐ray Raman scattering experiments. The simplicity of the experimental device makes it easily implemented on a classical X‐ray absorption beamline. This improvement in the fluorescence detection is of particular importance when the probed element is embedded in a complex and/or heavy matrix, for example in environmental sciences. 相似文献