A micro channel-cut crystal X-ray monochromator for a self-seeded hard X-ray free-electron laser
A micro channel-cut crystal X-ray monochromator for a self-seeded hard X-ray free-electron laser
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用于自播种硬X射线自由电子激光器的微通道切割晶体X射线单色仪
DOI：
10.1107/s1600577519008841
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发表时间：
2019
影响因子：
2.5
通讯作者：
and Makina Yabashi
中科院分区：
文献类型：
--
作者：
Taito Osaka;Ichiro Inoue;Ryota Kinjo;Takashi Hirano;Yuki Morioka;Yasuhisa Sano;Kazuto Yamauchi;and Makina Yabashi
研制了一种沟道宽度为90 μm的沟道切割Si（111）晶体，用于实现硬X射线自由电子激光（XFEL）的反射自籽晶。利用该晶体，从在第一波荡器部分中产生的宽带XFEL脉冲产生单色种子脉冲，该宽带XFEL脉冲在10 keV下具有119 fs的光学延迟。 小的光学延迟允许通过使用用于放置在两个波荡器区段之间的电子束的小的磁弯道而在种子光脉冲与电子聚束之间的时间重叠。峰值反射率达到67%，与理论值81%相比是合理的。通过使用这种单色器，在SACLA获得了光谱中没有宽带背景的单色种子脉冲，其宽带XFEL脉冲的转换效率为2 × 10−2，比使用薄金刚石（400）单色器的透射自播种的理论效率高100倍。
A channel-cut Si(111) crystal with a channel width of 90 µm was developed for achieving reflection self-seeding in hard X-ray free-electron lasers (XFELs). With the crystal a monochromatic seed pulse is produced from a broadband XFEL pulse generated in the first undulator section with an optical delay of 119 fs at 10 keV. The small optical delay allows a temporal overlap between the seed optical pulse and the electron bunch by using a small magnetic chicane for the electron beam placed between two undulator sections. Peak reflectivity reached 67%, which is reasonable compared with the theoretical value of 81%. By using this monochromator, a monochromatic seed pulse without broadband background in the spectrum was obtained at SACLA with a conversion efficiency from a broadband XFEL pulse of 2 × 10−2, which is ∼10 times higher than the theoretical efficiency of transmission self-seeding using a thin diamond (400) monochromator.