AN ELECTRON-TRACKING COMPTON TELESCOPE FOR A SURVEY OF THE DEEP UNIVERSE BY MeV GAMMA-RAYS-猫眼课题宝

DOI：

10.1088/0004-637x/810/1/28

发表时间：

2015-07

期刊：

The Astrophysical Journal

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

T. Tanimori;H. Kubo;A. Takada;S. Iwaki;S. Komura;Shunsuke Kurosawa;Y. Matsuoka;K. Miuchi;S. Miyamoto;T. Mizumoto;Y. Mizumura;K. Nakamura;S. Nakamura;M. Oda;J. Parker;T. Sawano;S. Sonoda;T. Takemura;D. Tomono;K. Ueno

MeV γ射线的光子成像由于背景大、图像不清晰而存在严重困难，这是由于探测中康普顿散射物理参数确定的不完整性造成的，缺乏反冲电子的方向信息。最近在MeV波段的主要使命/仪器，康普顿伽马射线天文台/COMPTEL，即康普顿照相机（CC），只探测到2030个持久源。这与GeV波段的10000源形成鲜明对比。在这里，我们报告的电子跟踪康普顿相机（ETCC）的性能，并证明它有一个很好的潜力，以突破这一停滞在MeV的伽玛射线天文学。ETCC通过测量3D反冲电子径迹提供康普顿散射的所有参数，然后恢复在CC中丢失的散射面偏差（SPD）。能量损失率（dE/dx），其中CCs无法测量，也得到了，并发现是有助于减少类似的条件下，在空间中的背景。因此，伽马检测的重要性提高了几倍。另一方面，SPD是定量确定点扩散函数（PSF）的必要条件。对于反冲电子的多次散射，SPD的分辨率提高到接近理论极限。有了这样一个良好确定的PSF，我们证明了第一次，它是可能的，以提供可靠的灵敏度在康普顿成像，而不利用优化算法。因此，这项研究突出了CC的根本弱点。相比之下，我们证明了ETCC在1 MeV下达到1 × 10−12 erg cm−2 s−1以下灵敏度的可能性。

Photon imaging for MeV gammas has serious difficulties due to huge backgrounds and unclearness in images, which originate from incompleteness in determining the physical parameters of Compton scattering in detection, e.g., lack of the directional information of the recoil electrons. The recent major mission/instrument in the MeV band, Compton Gamma Ray Observatory/COMPTEL, which was Compton Camera (CC), detected a mere ∼30 persistent sources. It is in stark contrast with the ∼2000 sources in the GeV band. Here we report the performance of an Electron-Tracking Compton Camera (ETCC), and prove that it has a good potential to break through this stagnation in MeV gamma-ray astronomy. The ETCC provides all the parameters of Compton-scattering by measuring 3D recoil electron tracks; then the Scatter Plane Deviation (SPD) lost in CCs is recovered. The energy loss rate (dE/dx), which CCs cannot measure, is also obtained, and is found to be helpful to reduce the background under conditions similar to those in space. Accordingly, the significance in gamma detection is improved severalfold. On the other hand, SPD is essential to determine the point-spread function (PSF) quantitatively. The SPD resolution is improved close to the theoretical limit for multiple scattering of recoil electrons. With such a well-determined PSF, we demonstrate for the first time that it is possible to provide reliable sensitivity in Compton imaging without utilizing an optimization algorithm. As such, this study highlights the fundamental weak-points of CCs. In contrast we demonstrate the possibility of ETCC reaching the sensitivity below 1 × 10−12 erg cm−2 s−1 at 1 MeV.

AN ELECTRON-TRACKING COMPTON TELESCOPE FOR A SURVEY OF THE DEEP UNIVERSE BY MeV GAMMA-RAYS

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