软X光平面镜反射率标定实验

报道了掠入射软X光平面镜反射率标定实验。实验利用北京同步辐射装置 (BSRF) 3W 1B束线及反射率计靶室 ,在束流 35mA～ 110mA、贮存环电子能量 2GeV专用光运行模式下 ,在 5 0eV～ 85 0eV能区分四个能段 ,进行了 5°掠入射Ni平面镜反射率标定实验。标定过程中用高灵敏度无死层的硅光二极管代替X射线二极管作探测器 ,输出信号提高 2～ 3个量级 ,可标定能区从 15 0eV～ 2 70eV拓展到 5 0eV～ 85 0eV ,给出了完整的 5°Ni平面镜反射率标定曲线。最后把实验数据与理论计算作了比对并进行了分析。     

Gamma Spectroscopy of Hf-178m2 Using Synchrotron X-Rays

Preliminary survey experiments have been performed to examine the triggering of gamma emission from the 31-year Hf-178m2 isomer using intense monochromatic synchrotron radiation from the X15A beamline at the National Synchrotron Light Source at Brookhaven National Laboratory. Initial studies were performed to probe incident photon energies over the L ₁, L ₂, and L ₃ X-ray edges of Hf and the 12–13 keV range. Resonances larger than the experimental minimum detectable level of 10⁻²⁵ cm² keV were not observed. This revised version was published online in August 2006 with corrections to the Cover Date.     

电子储存环的纵向粒子动力学理论及800MeV同步辐射储存环的相稳定区、慢加速方案

本文阐述了电子储存环的纵向粒子动力学理论,在此基础上计算了合肥同步辐射储存环的相稳定区,并给出了该储存环的慢加速设计方案。     

合肥800MeV电子储存环同步辐射特性

以石英卤钨灯作为光谱辐照度标准光源，测量了在３００－８００ｎｍ波段的合肥ＭｅＶ电子储存环同步辐射的相对光谱分布；并在４０５ｎｍ波长处测量了辐射源的角分布和偏振特性，在实验误差范围内，测量结果与理论计算值相符，相对光谱分布偏差为１．５％，角分布和偏振特性偏差小于５％。     

The analysis of slightly distorted SAXS layer line patterns from fibrillar two-phase systems with short-range order

The information content of small-angle x-ray scattering from fibrillar two-phase systems under strain is discussed. The experimental background is a study of SBS star block copolymer samples during elongation using synchrotron radiation and a two-dimensional detector. The samples exhibit a layer line pattern with the slight indication of a four-point diagram. The theoretical considerations are verified using the experimental data.Special scattering curves (sections and projections) can be extracted from the scattering pattern and are used to describe mathematical peculiarities of the pattern and their physical background. The scope of the paper covers product separability in cylindrical coordinates and an analysis of the separated factors. From the physical point of view information is gained on the validity of the approximation by a one-dimensional fibrillar system and the order within bundles of fibrils. An expression is given for the background scattering caused by an ensemble of non-identical oblong particles, organized in bundles of oriented fibrils. The difference in the information on the structure, obtainable from either section or projection, is discussed.Dedicated to Prof. Dr. Wilhelm Ruland on the occasion of his 65th birthday     

Pressure-Induced Structural Deformations in SeO2

The high-pressure behavior of low-dimensional selenium dioxide SeO₂ (P4₂/mbc, Z=8) is studied with Raman scattering and synchrotron angle-dispersive X-ray powder diffraction in a diamond anvil cell up to 23 GPa at room temperature. Pressure-induced transformations in this material involve a sequence of structural distortions of the chain structure. The transformation occuring above 7.0 GPa is due to symmetry lowering to space group Pbam (Z=8) without major changes of the crystal lattice dimensions and coordination around the Se atoms. Like in the ambient pressure polymorph, the structural unit is a SeO₃E polyhedron, where E is a Se non-bonded electron lone pair, or an irregular tetrahedron with the O atoms and Se lone pair at the vertices. Further structural transitions above 17 GPa are likely to be the result of additional distortions leading to monoclinic symmetry of the crystal structure. All transformations are reversible with little hysteresis.     

Studies on the repassivation behavior of aluminum and aluminum alloy exposed to chromate solutions

This study explores the repassivation ability of a scratch in a chromate conversion coating (CCC) on aluminum alloy, AA2024‐T3, and hence evaluates the theory of migration of hexavalent chromium ions from the protected surface of the aluminum alloy to the exposed surface. To confirm that protection was indeed restored by hexavalent chromium ions, the repassivation of a scratch on pure aluminum exposed to a dichromate solution was studied. This forms the simplest subsystem model of the CCC on the alloy in which the CCC is replaced by pure hexavalent chromium and alloy with pure aluminum. Open‐circuit potential measurements, synchrotron infrared microspectroscopy (SIRMS) and secondary ion mass spectroscopy (SIMS) have been used judiciously to evaluate the repassivation behavior. Results indicate that the dichromate ions have high mobility. The slow migration of Cr(VI) ions from the protected surface to the scratch is observed to result in repassivation, as seen from the steady increase in the potential in 0.05 M NaCl solution. The results obtained from SIMS and SIRMS confirm the migration of the oxyanions from the protected region to the metal surface exposed by the scratch. The SIRMS results indicate the formation of an Al(III)–Cr(VI) complex, proposed and shown to be formed in the pits. Copyright © 2003 John Wiley & Sons, Ltd.     

基于加窗傅立叶变换的SR-CT滤波反投影重建

SR-CT(Synchrotron Radiation Computed Tomography同步辐射X射线计算机断层扫描)实验中,原始投影图像存在噪声,从而影响了滤波反投影重建图像的质量.为提高重建图像质量,提出了一种基于加窗傅立叶变换滤波改进重建图像质量的方法.通过对原始投影图像噪声和滤波反投影算法的讨论,对利用该方法提高重建图像质量的可行性进行了分析.利用加窗傅立叶滤波方法对两组SR-CT实验得到的投影图像分别进行了处理,抑制了原始投影图像的噪声,提高了重建图像的质量.实验的结果验证了该方法的有效性.     

同步辐射激发直接干化学刻蚀

同步辐射激发直接光化学刻蚀是近年来发展的一项新技术 ,它不需要常规光刻中的光刻胶工艺 ,用表面光化学反应直接将图形写到半导体材料的表面上。由于所用的同步辐射在真空紫外 (VUV)波段 ,理论上的分辨率可以达到电子学的量子极限 ,且没有常规工艺中的表面损伤和化学污染 ,是一种非常具有应用潜力的技术。本文的最后部份重点讨论了与上述技术密切相关的VUV和软X射线激发的表面光化学反应机理。     

Design of slow extraction system for therapy synchrotron

Based on the optimized design of the lattice for therapy synchrotron and considering the requirement of radiation therapy, the third order resonant extraction is adopted. Using the momentum-amplitude selection method, the extraction system is designed and optimized. An extraction efficiency of more than 97% and a momentum spread less than 0.11% are obtained.