抄録
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 620cm2 at 8 keV, 178cm2 at 30 keV, and 82cm2 at 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 150cm2 at 30 keV and 55cm2 at 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.
本文言語 | 英語 |
---|---|
論文番号 | 044001 |
ジャーナル | Journal of Astronomical Telescopes, Instruments, and Systems |
巻 | 4 |
号 | 1 |
DOI | |
出版ステータス | 出版済み - 01-01-2018 |
All Science Journal Classification (ASJC) codes
- 電子材料、光学材料、および磁性材料
- 制御およびシステム工学
- 器械工学
- 天文学と天体物理学
- 機械工学
- 宇宙惑星科学