Application of composite-layer mirror to soft x-ray telescopes
Application of composite-layer mirror to soft x-ray telescopes
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DOI：
10.1117/12.552461
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发表时间：
2004-10
期刊：
影响因子：
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通讯作者：
Y. Ogasaka;C. Sakai;K. Tamura;N. Yamada;K. Yamashita
中科院分区：
文献类型：
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作者：
Y. Ogasaka;C. Sakai;K. Tamura;N. Yamada;K. Yamashita
低温探测器的最新发展使发射线和吸收线/边缘结构的高分辨率诊断成为可能。这些研究对于研究星际/星系间等离子体的物理学和黑洞周围物质的动力学非常重要。用于此目的的软X射线望远镜，灵敏度可达10 keV，通常使用Au，Pt或Ir来设计，因为它们具有大的电子密度和大的临界角。但实际上，这些材料在2--4keV范围内具有宽而深的M壳层吸收边结构，在几~ 8 keV范围内并不十分适用。考虑到吸收边缘和薄膜特性，C或Ni可以是替代品。然而，这些材料单独不能是良好的反射镜，再次从感兴趣的能量区域（0.1-10 keV）中的吸收边缘。我们设计了由C，Ni和Pt组成的复合结构，厚度为30到300埃，以获得整个能量区域的平滑和高反射率。测试制造表明界面粗糙度与预期一样低，表明材料匹配也很好。我们将这一结果应用于NeXT/软X射线望远镜的基线设计中，用C-Ni-Pt复合材料替代现有材料（Au），在2-8 keV范围内获得了20%的有效面积。
Recent development of cryogenic detectors enabled high resolution diagnostics of emission line and absorption line/edge structures. These studies are quite important to investigate physics of interstellar/intergalactic plasma and dynamics of matters around black holes, for example. Soft X-ray telescopes for such purpose, sensitive up to 10 keV, are usually designed using Au, Pt, or Ir for their large electron density and large critical angle. However in fact, these materials are not very suitable in a few to 8 keV region, because they have wide and deep M-shell absorption edge structures in 2--4 keV region. Considering absorption edges and also thin-film characteristics, C or Ni can be alternatives. However, these materials alone cannot be a good mirror, again from absorption edges in the energy region of interest (0.1-10 keV). We designed composite structure consisting of C, Ni and Pt with thickness of 30 to 300 A, to get smooth and high reflectivity all across the energy region. Test fabrication showed interfacial roughness is as low as expected, indicating match of materials is also good. We applied this result to the baseline design of NeXT/Soft X-ray Telescope, by substituting current material (Au) with C-Ni-Pt composite, and obtained 20% larger effective area in 2-8 keV region.