On-ground calibration of the Hitomi Hard X-ray Telescopes
On-ground calibration of the Hitomi Hard X-ray Telescopes
复制标题
Hitomi 硬 X 射线望远镜的地面校准
DOI：
10.1117/1.jatis.4.1.011210
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
et al.
中科院分区：
文献类型：
--
作者：
Mori H.;Miyazawa T.;Awaki H.;Matsumoto H.;et al.
我们提出了硬X射线望远镜（HXTs）的Hitomi（ASTRO-H）卫星上的X射线特性。在SPring-8 BL 20 B2光束线和ISAS/JAXA 27-m光束线上进行了测量。由半功率直径定义的角分辨率在8 keV时为1.9′（HXT-1）和2.1′（HXT-2），在30 keV时为1.9′，在50 keV时为1.8′。每个反射镜模块的有效面积在8 keV时为620 cm 2，在30 keV时为178 cm 2，在50 keV时为82 cm 2。虽然角分辨率略低于要求（1.7′），但有效面积充分超过了30 keV时150 cm 2和50 keV时55 cm 2的要求。有效面积的离轴测量结果表明，在50 keV时，视场为6.1′，在30 keV时为7.7′，在8 keV时为9.7′。我们证实，通过按设计安装预准直器，杂散光的主要成分显著减少。通过对实验数据的详细分析，发现反射镜反射面的形状误差是影响角分辨率的主要因素，反射面的形状误差、反射面的定位误差以及反射面形状的圆锥近似可以完全解释角分辨率的下降。我们发现，有效面积为80%左右 在40 keV以下，它们的设计值，而它们急剧下降，超过40 keV，并成为只有1.50%。我们研究了这种突然下降，发现既不是多层膜设计的错误，也不是由箔的定位误差引起的入射角的误差可以是原因。从散焦图像的每个箔对的反射轮廓强烈地表明，箔的形状误差可能会导致在较高的能量在有效面积的减少。
We present x-ray characteristics of the Hard X-ray Telescopes (HXTs) on board the Hitomi (ASTRO-H) satellite. Measurements were conducted at the SPring-8 BL20B2 beamline and the ISAS/JAXA 27-m beamline. The angular resolution defined by a half-power diameter was 1.9′ (HXT-1) and 2.1′ (HXT-2) at 8 keV, 1.9′ at 30 keV, and 1.8′ at 50 keV. The effective area was found to be 620 cm2at 8 keV, 178 cm2at 30 keV, and 82 cm2at 50 keV per mirror module. Although the angular resolutions were slightly worse than the requirement (1.7′), the effective areas sufficiently exceeded the requirements of 150 cm2at 30 keV and 55 cm2at 50 keV. The off-axis measurements of the effective areas resulted in the field of view being 6.1′ at 50 keV, 7.7′ at 30 keV, and 9.7′ at 8 keV in diameter. We confirmed that the main component of the stray x-ray light was significantly reduced by mounting the precollimator as designed. Detailed analysis of the data revealed that the angular resolution was degraded mainly by figure errors of mirror foils, and the angular resolution is completely explained by the figure errors, positioning errors of the foils, and conical approximation of the foil shape. We found that the effective areas were ∼80 % of the designed values below 40 keV, whereas they steeply decline above 40 keV and become only ∼50 % . We investigated this abrupt decline and found that neither the error of the multilayer design nor the errors of the incident angles induced by the positioning errors of the foils can be the cause. The reflection profile of each foil pair from the defocused image strongly suggests that the figure errors of the foils probably bring about the reduction in the effective areas at higher energies.