在L2 30个月后对Gaia CCD的辐射效应
Radiation effects on the Gaia CCDs after 30 months at L2
摘要：
自2013年12月欧空局的盖亚卫星发射以来，卫星上的106个大尺寸科学CCD一直在L2运行。由于飞行任务的高精度测量要求和预测的L2质子环境相结合，在发射前很早就确定探测器受到的非电离辐射损害的影响可能对数据的科学价值造成重大限制。在本文中，我们比较了飞行前辐射诱导的电荷转移效率（CTI）的预测对飞行中的测量，特别侧重于电荷注入诊断，以及相关的这些CTI诊断结果与太阳质子事件数据。我们发现，L2-定向太阳活动发射以来一直相对较低，辐射损害（到目前为止）是低于原来的预期。尽管如此，有明确的情况下，地球指向太阳日冕物质抛射事件和CTI诊断随时间的突然变化之间的相关性。这些突然的跳跃是躺在一个相当恒定的增加CTI的顶部，我们表明，这主要是由于高能量银河宇宙射线的设备的连续轰击。我们研究的CTI水平低于预期的可能原因，以及检查控制有效载荷加热事件对CTI诊断的影响。CCD串行寄存器中辐射引起的CTI和电离辐射的影响也相应地低于预期，但这里不详细讨论这些问题。
英文摘要：
Since the launch of ESA's Gaia satellite in December 2013, the 106 large-format scientific CCDs onboard have been operating at L2. Due to a combination of the high-precision measurement requirements of the mission and the predicted proton environment at L2, the effect of non-ionizing radiation damage on the detectors was early identified pre-launch as potentially imposing a major limitation on the scientific value of the data. In this paper we compare pre-flight radiation-induced Charge Transfer Inefficiency (CTI) predictions against in-flight measurements, focusing especially on charge injection diagnostics, as well as correlating these CTI diagnostic results with solar proton event data. We show that L2-directed solar activity has been relatively low since launch, and radiation damage (so far) is less than originally expected. Despite this, there are clear cases of correlation between earth-directed solar coronal mass ejection events and abrupt changes in CTI diagnostics over time. These sudden jumps are lying on top of a rather constant increase in CTI which we show is primarily due to the continuous bombardment of the devices by high-energy Galactic Cosmic Rays. We examine the possible reasons for the lower than expected levels of CTI as well as examining the effect of controlled payload heating events on the CTI diagnostics. Radiation-induced CTI in the CCD serial registers and effects of ionizing radiation are also correspondingly lower than expected, however these topics are not examined here in detail.
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