Yu X J, Chi X, Smulders T, Wee A T S, Rusydi A, Sanchez Del Rio M, Breese M B H
Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603, Singapore.
Department of Engineering Physics, Fonty University of Applied Sciences, 5615DB Eindhoven, The Netherlands.
J Synchrotron Radiat. 2022 Sep 1;29(Pt 5):1157-1166. doi: 10.1107/S160057752200707X. Epub 2022 Aug 12.
Monochromators for synchrotron radiation beamlines typically use perfect crystals for the hard X-ray regime and gratings for soft X-rays. There is an intermediate range, typically 1-3 keV (tender X-rays), which common perfect crystals have difficulties covering and gratings have low efficiency, although some less common crystals with high d-spacing could be suitable. To evaluate the suitability of these crystals for a particular beamline, it is useful to evaluate the crystals' performance using tools such as ray-tracing. However, simulations for double-crystal monochromators are only available for the most used crystals such as Si, Ge or diamond. Here, an upgrade of the SHADOW ray-tracing code and complementary tools in the OASYS suite are presented to simulate high d-spacing crystals with arbitrary, and sometimes complex, structures such as beryl, YB, muscovite, etc. Isotropic and anisotropic temperature factors are also considered. The YB crystal with 1936 atomic sites in the unit cell is simulated, and its applicability for tender X-ray monochromators is discussed in the context of new low-emittance storage rings.
同步辐射光束线的单色仪通常在硬X射线区域使用完美晶体，在软X射线区域使用光栅。存在一个中间范围，通常为1 - 3千电子伏特（软X射线），普通的完美晶体难以覆盖该范围，而光栅在该范围效率较低，不过一些具有高d间距的不太常见的晶体可能适用。为了评估这些晶体对特定光束线的适用性，使用光线追踪等工具评估晶体性能很有用。然而，双晶单色仪的模拟仅适用于最常用的晶体，如硅、锗或金刚石。在此，展示了SHADOW光线追踪代码以及OASYS套件中的补充工具的升级版本，以模拟具有任意（有时是复杂）结构的高d间距晶体，如绿柱石、YB、白云母等。还考虑了各向同性和各向异性温度因子。对单位晶胞中有1936个原子位点的YB晶体进行了模拟，并在新型低发射率储存环的背景下讨论了其在软X射线单色仪中的适用性。
