High-Resolution Structure Analysis Using Synchrotron Radiation with a Multiple-Detector System

研制了一种新型的六臂同步辐射粉末衍射仪。五个探测器臂，以25‰的间隔径向连接到2rheta轴，组成一个多探测器系统。5个闪烁计数器与各臂上的扁平Ge（111）晶体分析仪相耦合，可以同时记录整个粉末模式，该模式被划分为5个区段，具有相等的2rheta跨度。光学设计是基于平行光束的平样反射几何。在固定入射角的不对称衍射中，采用2阶跃扫描技术采集了光强数据。在传统的单臂扫描模式下，第六臂可以用于多用途。它可以配备各种分析仪，如长水平平行狭缝，平面或通道切割晶体分析仪，接收狭缝，固体探测器。衍射仪在1995年4月在筑波光子工厂安装在光束线BL-4B上，并且从那时起进行了测试操作。从1996年4月开始，整个系统已被一般用户用于高分辨率粉末衍射实验。结果表明，硅粉的（111）反射峰的半峰宽度为0.022，最大峰强度大于40000次/秒。通过使用聚焦镜，最大峰值强度增加到每秒10万次以上。以0.004(2)为步长，在4小时内即可扫描到130范围内的整个粉末图案。结构改进的结果将在其他地方发表。

A new powder diffractometer for synchrotron radiation with six detector arms has been constructed. Five detector arms, which are attached radially at intervals of 25ﾟ to the 2rheta-axis, compose a multiple-detector system. Five scintillation counters coupled with a flat Ge (111) crystal analyzer on respective arms can record simultaneously the whole powder pattern divided into five segments with an equal 2rheta span. The optics design is based on the flat-specimen-reflection geometry using parallel-beam. The intensity data are collected by using a 2rheta-step-scan technique in the asymmetric diffraction at a fixed incident angle. A sixth detector arm can be used for multi-purpose in the conventional single-arm-scan mode. It can equip various kinds of analyzers such as long horizontal parallel slits, a flat or channel-cut crystal analyzer, a receiving slit, a solid state detector. The diffractometer was installed at the beam-line BL-4B at the Photon Factory in Tsukuba in April, 1995, and test operations had been conducted since then. From the April of 1996, the whole system has been used by general users for high-resolution powder diffraction experiments. It recorded the fullwidth at half-maximum of 0.022ﾟ and the peak maximum intensity of more than 40,000 counts per second for the (111) reflection from Si powder. By the use of a focusing mirror, the maximum peak intensity was increased to more then 100,000 counts per second. The whole powder pattern in the 2rheta-range of 130ﾟ could be step-scanned at a step interval of 0.004ﾟ (2rheta) in just 4 hours. Results of structure refinements will be published elsewhere.