Discrimination of background events in the PolarLight X-ray polarimeter

In-orbit Operation and Performance of the CubeSat Soft X-ray Polarimeter PolarLight

PolarLight is a compact soft X-ray polarimeter onboard a CubeSat, which was launched into a low-Earth orbit on October 29, 2018. In March 2019, PolarLight started full operation, and since then, regular observations with the Crab nebula, Sco X-1, and background regions have been conducted. Here we report the operation, calibration, and performance of PolarLight in the orbit. Based on these, we discuss how one can run a low-cost, shared CubeSat for space astronomy, and how CubeSats can play a role in modern space astronomy for technical demonstration, science observations, and student training.

PolarLight: a CubeSat X-ray Polarimeter based on the Gas Pixel Detector

The gas pixel detector (GPD) is designed and developed for high-sensitivity astronomical X-ray polarimetry, which is a new window about to open in a few years. Due to the small mass, low power, and compact geometry of the GPD, we propose a CubeSat mission Polarimeter Light (PolarLight) to demonstrate and test the technology directly in space. There is no optics but a collimator to constrain the field of view to 2.3 degrees. Filled with pure dimethyl ether (DME) at 0.8 atm and sealed by a beryllium window of 100 micron thick, with a sensitive area of about 1.4 mm by 1.4 mm, PolarLight allows us…

Modeling the in-orbit background of PolarLight

PolarLight is a gas pixel X-ray polarimeter mounted on a CubeSat, which was launched into a Sun-synchronous orbit in October 2018. We build a mass model of the whole CubeSat with the Geant4 toolkit to simulate the background induced by the cosmic X-ray background (CXB) and high energy charged particles in the orbit. The simulated energy spectra and morphologies of event images both suggest that the measured background with PolarLight is dominated by high energy electrons, with a minor contribution from protons and the CXB. The simulation reveals that, in the energy range of 2-8 keV, there are …

用于X射线天体物理学的HaloSat和PolarLight CubeSat任务

The HaloSat and PolarLight CubeSat Missions for X-ray Astrophysics

本文介绍HaloSat和PolarLight两个CubeSat任务，展示其在X射线天体物理学中的有效平台能力及学生训练价值。

Event Selection and Background Rejection in Time Projection Chambers Using Convolutional Neural Networks and a Specific Application to the AdEPT Gamma-ray Polarimeter Mission

The Advanced Energetic Pair Telescope gamma-ray polarimeter uses a time projection chamber for measuring pair production events and is expected to generate a raw instrument data rate four orders of magnitude greater than is transmittable with typical satellite data communications. GammaNet, a convolutional neural network, proposes to solve this problem by performing event classification on-board for pair production and background events, reducing the data rate to a level that can be accommodated by typical satellite communication systems. In order to train GammaNet, a set of 1.1x10^6 pair prod…

在70-300 keV能量范围内空间科学用细间距CdTe-based硬X射线偏振计性能

Fine pitch CdTe-based Hard-X-ray polarimeter performance for space science in the 70-300 keV energy range

X射线天体物理源几乎完全通过成像，光谱和定时分析来表征。然而，由于中子星或黑洞中存在的某些辐射机制仍不清楚，因此需要更多的观测参数。偏振测量将在区分不同的X射线发射模型中发挥关键作用。这种能力成为下一代高能空间提案的强制性要求。我们已经开发了一种基于CdTe的细间距成像光谱仪，Caliste，能够响应这些新的要求。在580微米的间距和1 keV的能量分辨率为60 keV时，我们能够准确地重建光子的入射通量的偏振角和偏振分数，这些光子在晶体内康普顿扩散后散射90°。由于其在成像和光谱测定方面的高性能，Caliste成为高能偏振测量的强大设备。在本文中，我们提出了这种测量的原理和获得的结果：一方面，我们描述了我们已经开发的模拟工具，以预测在50-300 keV的能量范围内的极化性能。另一方面，我们比较模拟结果与实验数据在ESRF ID 15 A（欧洲同步辐射设施）使用单能量偏振光束之间的35和300千电子伏的调整。我们表明，它是可能的，与此检测器，以确定高精度的偏振参数（方向和分数）为不同的照射条件。应用一个明智的能源选择我们的数据集，我们达到了显着的灵敏度水平，其特征在于在200-300千电子伏范围内的最佳品质因数为0.78。我们还评估了我们的设备在70千电子伏，其中硬X射线镜已经可用的灵敏度;测得的Q因子为0.64，在70千电子伏。