Modeling effects of charge sharing on the response of the FOXSI sounding rockets
Modeling effects of charge sharing on the response of the FOXSI sounding rockets
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模拟电荷共享对 FOXSI 探空火箭响应的影响
DOI：
10.1117/12.2629443
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Krucker Sam
中科院分区：
文献类型：
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作者：
Duncan Jessie;Athiray P. Subramania;Musset Sophie;Vievering Juliana;Nagasawa Shunsaku;Buitrago Casas Juan Camilo;Glesener Lindsay;Takahashi Tadayuki;Watanabe Shin;Zhang Yixian;Christe Steven;MacDowell Alastair;Krucker Sam
聚焦光学X射线太阳成像仪（FOXSI）探空火箭是第一个太阳专用的直接聚焦硬X射线（HXR）仪器。FOXSI火箭使用Wolter-1型HXR光学器件和固态双面条形探测器。太阳HXR源的FOXSI图像受到光学器件的点扩散函数、探测器到条带交叉点的2D分割以及探测器读出中的噪声的影响。对于FOXSI-4，新的高分辨率光学器件将导致仪器的角分辨率受到其CdTe探测器的最小条带间距（60 μm）的限制。FOXSI图像还受到探测器中电荷共享的影响，当一个入射光子在多个相邻条带中产生信号时。光子入射到条带边界越近，电荷共享越有可能，使其成为子条带位置相关效应。在同步加速器光束线（高级光源）上对FOXSI-3 CdTe探测器（带间距为60 μm）进行的测试允许表征电荷共享事件。这些知识被用来开发新的方法，以实现FOXSI探测器的子带分辨率（0.6-3”，取决于入射光子位置），未来适用于FOXSI-4探测器为了评估这些方法的性能，已经开发了结合FOXSI-3光学和检测器响应的模型，后者在系统中结合了实验室测量的电荷共享特性。使用该模型，生成的源与FOXSI-3系统卷积，以模拟FOXSI数据。然后，相应的反卷积过程使用新的成像方法从模拟数据中提取重建的源，并且可以比较原始源和重建的源。我们表明，重建的源近似于原始的更高的空间分辨率比使用基于条带的位置知识的结果。值得注意的是，我们展示了一种新的能力，以解决独立的源位于只有一个带间距。
The Focusing Optics X-ray Solar Imager (FOXSI ) sounding rockets are the first solar-dedicated direct-focusing hard X-ray (HXR) instruments. FOXSI rockets use Wolter-1 style HXR optics and solid state double-sided strip detectors. FOXSI images of solar HXR sources are influenced by the point spread function of the optics, the 2D segmentation of the detector into strip intersections, and noise in the detector readout. For FOXSI-4, new high-resolution optics will cause the instrument angular resolution to be limited by the minimum strip pitch of its CdTe detectors (60 μm).FOXSI images are also affected by charge sharing in the detector, when one incident photon causes signals in multiple adjacent strips. Charge sharing is more likely the closer a photon is incident to a strip boundary, making it a sub-strip-position-dependent effect. Tests of a FOXSI-3 CdTe detector (with 60 μm strip pitch) at a synchrotron beamline (the Advanced Light Source) have allowed for characterization of charge shared events. This knowledge is used to develop new methods for achieving sub-strip resolution in FOXSI detectors (0.6-3", depending on incident photon position), applicable in the future to the FOXSI-4 detectors (or other similar systems).To evaluate the performance of these methods, a model has been developed combining the FOXSI-3 optical and detector response, the latter incorporating lab-measured properties of charge sharing in the system. Using this model, generated sources are convolved with the FOXSI-3 system to simulate FOXSI data. A corresponding deconvolution process then extracts a reconstructed source from the simulated data using the new imaging methods, and the original and reconstructed sources can be compared. We show that the reconstructed source approximates the original with higher spatial resolution than that which results from using strip-based position knowledge only. Notably, we demonstrate a new ability to resolve independent sources located only one strip pitch apart.