SYNCHROTRON CRYSTALLOGRAPHY SMALL GAP UNDULATOR FOR MAD CRYSTALLOGRAPHY

NSLS与日本Spring-8合作，设计了 搭建并测试了一台小间隙波荡器样机，其结构紧凑。 允许它驻留在X9和X29存在的射频腔之间。 该样机在真空中波动(IVUN)，周期为11毫米，一个 最小可用间隙为3.3 mm(最大为10 mm)和磁场 目前在光束线直线段安装了0.678吨 X13。这些参数导致测量的基波电压为4.6keV， 二次谐波为8.7keV，三次谐波为13.9keV。这个 IVUN的亮度与X25相当(略高) 摇摆器。因为它的亮度明显低于 APS器件，必然是光谱宽度更大，在 足以围绕选定吸收进行疯狂实验的事实 如果仔细选择了峰值能量，则会显示边缘。X13波荡器 将为设计和施工一个完整的 用于MAD数据采集的专用小间隙波动器站 NSLS的东南边缘。这种设施的可获得性将大大 增加科学工作者可以使用的疯狂天数 社区，并将作为进一步发展和 将小间隙波荡器作为主要资源应用于 结构、分子和细胞生物学。

The NSLS, in collaboration with SPring-8, Japan, has designed, built and tested a prototype small-gap undulator, whose compactness allows it to reside between the rf cavities that exist at X9 and X29. This prototype in-vacuum undulator (IVUN), with a period of 11 mm, a minimum useful gap of 3.3 mm (maximum of 10 mm) and a magnetic field of 0.678 T is currently installed in the straight section for beamline X13. These parameters lead to a measured fundamental at 4.6 keV, second harmonic at 8.7 keV, and a third harmonic at 13.9 keV. The brightness of IVUN is comparable (slightly higher) than the X25 wiggler. Since its brightness is significantly less than that of the APS devices, the corollary is that the spectral width is greater, in fact sufficient to perform a MAD experiment around selected absorption edges if the peak energy is carefully selected. The X13 undulator will provide the basis for the design and construction of a completely dedicated small-gap undulator station for MAD data collection at the Se edge at NSLS. The availability of such a facility will greatly increase the total number of MAD days available to the scientific community and will serve as a model for the further development and implementation of small-gap undulators as major resources in structural, molecular and cellular biology.