Continuous-scan capability at SSRL and applications to X-ray diffraction

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• 作者：Chunlei Li ; Andrew M. Kiss ; Douglas G. Van Campen ; Alex Garachtchenko ; Yuriy Kolotovsky ; Kevin Stone ; Yahong Xu ; Wenjun Zhang and Jeff Corbett
• 关键词：continuous scan ; step scan ; X-ray diffraction ; efficiency
• 刊名：Journal of Synchrotron Radiation
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：23
• 期：4
• 页码：909-918
• 全文大小：1001K
• ISSN：1600-5775

文摘

Typical X-ray diffraction measurements are made by moving a detector to discrete positions in space and then measuring the signal at each stationary position. This step-scanning method can be time-consuming, and may induce vibrations in the measurement system when the motors are accelerated and decelerated at each position. Furthermore, diffraction information between the data points may be missed unless a fine step-scanning is used, which further increases the total measurement time. To utilize beam time efficiently, the motor acceleration and deceleration time should be minimized, and the signal-to-noise ratio should be maximized. To accomplish this, an integrated continuous-scan system was developed at the Stanford Synchrotron Radiation Lightsource (SSRL). The continuous-scan system uses an in-house integrated motor controller system and counter/timer electronics. SPEC software is used to control both the hardware and data acquisition systems. The time efficiency and repeatability of the continuous-scan system were tested using X-ray diffraction from a ZnO powder and compared with the step-scan technique. Advantages and limitations of the continuous-scan system and a demonstration of variable-velocity continuous scan are discussed.