Demonstration of polarization sensitivity of emulsion-based pair conversion telescope for cosmic gamma-ray polarimetry
Demonstration of polarization sensitivity of emulsion-based pair conversion telescope for cosmic gamma-ray polarimetry
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用于宇宙伽马射线偏振测量的乳剂对转换望远镜偏振灵敏度演示
DOI：
10.1016/j.nima.2016.07.033
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
Hiroki Rokujo
中科院分区：
文献类型：
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作者：
Keita Ozaki;Satoru Takahashi;Shigeki Aoki;Keiki Kamada;Taichi Kaneyama;Ryo Nakagawa;Hiroki Rokujo
高能γ射线（10 MeV-100 GeV）的线偏振可以通过测量正负电子对的方位角和观察方位角分布的调制来探测。为了证明乳剂的γ射线偏振灵敏度，我们在SPring-8/LEPS上使用偏振γ射线束（0.8-2.4 GeV）进行了测试。乳胶轨迹使用扫描数据重建，并自动选择伽马射线事件。使用光学显微镜，在所观察到的2381个伽马射线转换中，在事件选择之后剩下1372个，在其方位角分布上，我们测量了调制。根据所选事件的方位角分布，测量到调制因子为0.21+0.11−0.09，由此确定检测到非零调制，其显著性为3.06σ。这款有吸引力的旋光仪将应用于GRAINE项目，这是一个球载实验，使用基于乳液的对转换望远镜观测10-100 GeV宇宙伽马射线。
Linear polarization of high-energy gamma-rays (10MeV–100 GeV) can be detected by measuring the azimuthal angle of electron–positron pairs and observing the modulation of the azimuthal distribution. To demonstrate the gamma-ray polarization sensitivity of emulsion, we conducted a test using a polarized gamma-ray beam (0.8–2.4 GeV) at SPring-8/LEPS. Emulsion tracks were reconstructed using scanning data, and gamma-ray events were selected automatically. Using an optical microscope, out of the 2381 gamma-ray conversions that were observed, 1372 remained after event selection, on the azimuthal angle distribution of which we measured the modulation. From the distribution of the azimuthal angles of the selected events, a modulation factor of 0.21+0.11−0.09 was measured, from which the detection of a non-zero modulation was established with a significance of 3.06σ. This attractive polarimeter will be applied to the GRAINE project, a balloon-borne experiment that observes 10–100 GeV cosmic gamma-rays with an emulsion-based pair conversion telescope.