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arXiv 1607.04517astro-ph.IM
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临界角X射线透射光栅谱仪,具有扩展的带通和> 10,000的分辨率

Critical-angle x-ray transmission grating spectrometer with extended bandpass and resolving power > 10,000

Ralf K. Heilmann, Alexander R. Bruccoleri, Jeffery Kolodziejczak, Jessica A. Gaskin, Stephen L. O'Dell, Ritwik Bhatia, Mark L. Schattenburg

摘要:

天体物理学中的几个高优先级主题可以通过最先进的软X射线光栅光谱仪(XGS)来解决。基于临界角透射(CAT)光栅的探测器级、大面积(> 1,000 cm 2)、高分辨率(R > 3,000)XGS是高度可行的,即使对于角分辨率为5-10弧秒的望远镜也是如此。CAT XGS在执行X射线-测量型任务时可提供更高的性能。CAT光栅结合了闪耀反射光栅的优点(高效率,使用更高的衍射级)和透射光栅的优点(低质量,宽松的对准和温度要求,在高能量下透明),任务资源需求最小。它们是高效率闪耀透射光栅,由独立的超高纵横比光栅条组成,采用各向异性干法和湿法蚀刻技术由SOI晶片制成。闪耀是通过光栅条侧壁的反射实现的。硅与软X射线波段很好地匹配,现有的硅CAT光栅超过30%的绝对衍射效率,具有清晰的改进路径。涂覆有较重元素的CAT光栅允许将CAT光栅原理扩展到更高的能量和更大的角度,从而在更短的波长下实现更高的分辨率。我们展示了使用原子层沉积涂覆铂的CAT光栅的X射线数据,并展示了比硅更高的能量和更大的闪耀角。我们测量分辨率的CAT XGS由一个Wolter-I聚焦镜对GSFC和CAT光栅,在MSFC SLF进行。基于初步分析,18阶Al Ka双重峰的测量显示分辨率> 10,000。这表明,目前制造的CAT光栅与未来软X射线光谱任务的最先进的XGS设计兼容。

英文摘要:

Several high priority subjects in astrophysics can be addressed by a state-of-the-art soft x-ray grating spectrometer (XGS). An Explorer-scale, large-area (> 1,000 cm2), high resolving power (R > 3,000) XGS is highly feasible based on Critical-Angle Transmission (CAT) gratings, even for telescopes with angular resolution of 5-10 arcsec. Significantly higher performance can be provided by a CAT XGS on an X-ray-Surveyor-type mission. CAT gratings combine the advantages of blazed reflection gratings (high efficiency, use of higher diffraction orders) with those of transmission gratings (low mass, relaxed alignment and temperature requirements, transparent at high energies) with minimal mission resource demands. They are high-efficiency blazed transmission gratings that consist of freestanding, ultra-high aspect-ratio grating bars made from SOI wafers using anisotropic dry and wet etch techniques. Blazing is achieved through reflection off grating bar sidewalls. Silicon is well matched to the soft x-ray band, and existing silicon CAT gratings exceed 30% absolute diffraction efficiency, with clear paths for improvement. CAT gratings coated with heavier elements allow extension of the CAT grating principle to higher energies and larger angles, enabling higher resolving power at shorter wavelengths. We show x-ray data from CAT gratings coated with platinum using atomic layer deposition, and demonstrate blazing to higher energies and much larger blaze angles than possible with silicon. We measure resolving power of a CAT XGS consisting of a Wolter-I focusing mirror pair from GSFC and CAT gratings, performed at the MSFC SLF. Measurement of the Al Ka doublet in 18th order shows resolving power > 10,000, based on preliminary analysis. This demonstrates that currently fabricated CAT gratings are compatible with the most advanced XGS designs for future soft x-ray spectroscopy missions.

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