Feng Liangjie, Kang Le, Li Zhongliang, Zhao Feixun, Xu Chaoyin
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, People's Republic of China.
J Synchrotron Radiat. 2008 Mar;15(Pt 2):140-3. doi: 10.1107/S0909049507066368. Epub 2008 Feb 19.
A scanning dynamically focusing sagittal X-ray monochromator accepting 3 mrad x 0.1 mrad from a 6 T wiggler has been designed for XAFS measurements. In the energy range 4.1-12.4 keV, the slope error of the second cylindrical crystal caused by anticlastic bending must be less than 1/5 of the Darwin width of the crystal or the photon flux will decrease drastically. Two methods to minimize the anticlastic bending are proposed. Thin crystals with stiffening ribs and thin crystals with an aspect ratio equal to the ;golden value' are evaluated by finite-element analysis and by long-trace-profiler characterization. Both approaches are satisfactory, but the ;golden value' approach is preferred in this case for the second crystal of the new monochromator not only because it is easy to manufacture but also because the surface is smoother than the ribbed crystal.
已设计出一种用于XAFS测量的扫描动态聚焦矢状X射线单色仪，它可接收来自6T摆动器的3毫弧度×0.1毫弧度的X射线。在4.1 - 12.4keV的能量范围内，由反弯曲引起的第二个圆柱形晶体的斜率误差必须小于晶体达尔文宽度的1/5，否则光子通量将急剧下降。提出了两种最小化反弯曲的方法。通过有限元分析和长程轮廓仪表征对带有加强肋的薄晶体和长宽比等于“黄金值”的薄晶体进行了评估。两种方法都令人满意，但在这种情况下，对于新单色仪的第二个晶体，“黄金值”方法更受青睐，这不仅是因为它易于制造，还因为其表面比带肋晶体更光滑。
