Sensitivity of a photoelectric x-ray polarimeter for astronomy: the impact of the gas mixture and pressure
Sensitivity of a photoelectric x-ray polarimeter for astronomy: the impact of the gas mixture and pressure
复制标题
天文学光电 X 射线偏振计的灵敏度：气体混合物和压力的影响
DOI：
10.1117/12.459275
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
G. Spandre
中科院分区：
文献类型：
--
作者：
L. Pacciani;E. Costa;G. Di Persio;M. Feroci;P. Soffitta;L. Baldini;R. Bellazzini;A. Brez;N. Lumb;G. Spandre
在掠射望远镜的焦点上安装的微图样探测器是目前对天体x射线源线偏振进行灵敏、可靠测量的最有力工具。这种全新装置的实际实现是各种因素权衡的结果，与传统仪器方法相比，它可以提供突破性的灵敏度提高。灵敏度取决于光学元件的有效面积和探测器的调制系数和效率。后者通过各种因素强烈地依赖于填充气体，包括吸收概率、轨迹长度与像素大小、漂移过程中横向扩散引入的模糊。我们讨论了填充气体的选择对仪器灵敏度和工作波段的影响，而惰性气体驱动效率，有机淬火气体在减少散射和产生最直的轨迹以及减少扩散方面都有影响。讨论了低能取向偏振仪和高能取向偏振仪的设计方案。
A Micropattern detector in the focus of a grazing incidence telescope is nowadays the most powerful tool to perform a sensitive and reliable measurement of the linear polarization of celestial X-ray sources. The actual implementation of such a completely new device results from a trade-off of various factors and can provide a break-through increase of sensitivity with respect to traditional instrumental approaches. The sensitivity depends on the effective area of the optics and the modulation factor and efficiency of the detector. The latter strongly depends on the filling gas through various factors, including the absorption probability, the length of track versus the pixel size, the blurring introduced by the lateral diffusion during the drift. We discuss the impact of the choice of the filling gas on the sensitivity and on the operative band of the instrument, while the noble gases drive the efficiency, the organic quenching gases impact both in reducing the scattering and producing most straight tracks and on reducing diffusion. Some design solution are discussed both for a low energy oriented and high energy oriented polarimeters.