Gembicky Milan, Oss Dan, Fuchs Ryan, Coppens Philip
Department of Chemistry, State University of New York at Buffalo, NY 14260-3000, USA.
J Synchrotron Radiat. 2005 Sep;12(Pt 5):665-9. doi: 10.1107/S090904950501770X. Epub 2005 Aug 16.
A new high-speed high-repetition-rate X-ray beam shutter for time-resolved photocrystallography at synchrotron sources has been developed and tested. The new design is based on a commercially existing DC servomotor and a frequency-lock control capable linear amplifier. Accurate speed control combined with an air bearing results in extremely low jitter in the motor rotation. Measured jitter at rotation speeds of 12000 to 30000 r min-1 is less than 2 ns at a 6sigma confidence level. The chopper disc is interchangeable, allowing maximum flexibility. The chopper disc currently installed has 45 radial slots which allows synchronization from the 12th to the 20th subfrequencies of the orbit frequency of the Advanced Photon Source storage ring, corresponding to X-ray pulse frequencies of 13.6 to 22.6 kHz. At 30000 r min-1 the opening time window with a 350 microm slot size is 2.11 micros, and correspondingly less with smaller openings, which may be compared with the 3.68 micros orbit time of the Advanced Photon Source. The shutter provides high accuracy and efficient use of X-rays at a modest cost.
一种用于同步辐射源时间分辨光晶体学的新型高速高重复率X射线束快门已被开发并测试。新设计基于一种现有的商用直流伺服电机和一个具有锁频控制功能的线性放大器。精确的速度控制与空气轴承相结合，使得电机旋转时的抖动极低。在12000至30000转/分钟的转速下，在6σ置信水平下测得的抖动小于2纳秒。斩光盘是可互换的，具有最大的灵活性。目前安装的斩光盘有45个径向槽，可与先进光子源储存环轨道频率的第12至20个子频率同步，对应于13.6至22.6千赫兹的X射线脉冲频率。在30000转/分钟时，具有350微米槽尺寸的开启时间窗口为2.11微秒，开口越小相应时间越短，这可与先进光子源的3.68微秒轨道时间相比较。该快门以适度的成本提供了高精度和X射线的高效利用。
