Radiation damage in the Gaia focal plane: in-orbit data, charge-transfer simulations, and the impact on the astronomy achievable

欧空局盖亚任务于2013年12月启动，其雄心勃勃的目标是在其5年(外加1-4年延长)的生命周期内绘制出惊人的10亿个天文天体的地图。Gaia焦平面由106个定制设计的e2v ccd组成。探测器在轨道上时会受到辐射损伤，到目前为止的结果表明，这种损伤比发射前预测的要低得多。造成这种较低水平损伤的因素仍然没有得到证实，尽管有几个候选因素可能会出现这种变化。其一是挡板末端的纤维和冰的光散射增加了光学背景。另一个是设备在轨道上受到辐射的影响，其温度比发射前的测试活动低100K以上。俄亥俄州立大学目前的研究表明，这两个因素对所受损害的程度都有重大影响。为欧空局欧几里德飞行任务开发的模拟使用类似的探测器(斯科特费尔特)，尽管设计不同，但在帮助理解这些探测器中辐射损害过程背后的物理方面显示出巨大的希望。尽管俄勒冈大学对盖亚辐射战役数据(霍尔和干燥器)的发射前研究已经结束，但数据现在正从轨道上传回。使用这些信息，除了开发对GaIA探测器的OU模拟之外，学生将能够获得关于在轨道上的CCD中形成的陷阱的真实信息，并将这些信息反馈给其他任务研究(例如，欧几里德、SILE、WFIRST等)。然后，学生将继续从天文角度观察辐射损害将如何影响GAIA RVS在任务期间的输出(诺顿)。由CCD辐射损伤引起的拖尾可能导致感兴趣的对象与较暗的背景对象的混合增加，因此这可能导致径向速度测量的不确定性增加。随着辐射损害随着时间的推移而增加，不确定性也将增加，因此，对这种影响的分析和可能的纠正方法(与OU Euclid和SMILE研究相联系)将是主要感兴趣的。盖亚使天文学研究成为可能的这种破坏的影响将成为论文的最后一部分，将空间仪器和该学院的天文研究联系起来，并将对其他空间天文任务，如ESA欧几里得和柏拉图任务有所裨益。这项研究的成果将有额外的好处，它们将提供给S818：空间科学和技术硕士。盖亚案例研究由安德鲁·诺顿和大卫·霍尔共同撰写，通过教学在天文学和探测器技术之间建立了联系。通过这种跨学科研究在博士学位期间考虑两者之间的影响，将不仅在天文学和空间仪器研究之间，而且在空间科学和技术硕士课程的教学和研究之间提供进一步的联系(S818)。

Launched in December 2013, the ESA Gaia mission has the ambitious aim of mapping a staggering 1 billion astronomical objects over its 5 year (plus 1-4 year extension) lifetime. The Gaia focal plane is formed of 106 custom-designed e2v CCDs. The detectors are subject to radiation damage whilst in orbit and the results so far suggest that this damage is much lower than that predicted pre-launch.The contributing factors to this lower level of damage are still unconfirmed, although there are several candidates for this variation. One is the increased optical background from light scattering from fibres and ice on the end of the baffle. Another is the impact of the devices being irradiated in-orbit more than 100 K lower in temperature than in the pre-launch test campaigns. Current research at the OU suggests that both factors have a major impact on the level of damage received. Simulations developed for the ESA Euclid mission using similar detectors (Skottfelt), albeit of a different design, are showing great promise in aiding an understanding of the physics behind the processes of radiation damage in these detectors. Although the OU's pre-launch research on Gaia radiation campaign data (Hall and Dryer) has ended, data is now being returned from orbit. Using this information, alongside developing the OU simulations to the Gaia detectors, the student will be able to get real information on traps developing in the CCDs in-orbit, feeding this information back into other mission research (e.g. Euclid, SMILE, WFIRST etc).The student will then go on to look at how the radiation damage will affect the Gaia RVS output from an astronomy perspective during the mission (Norton). Smearing caused by CCD radiation damage can lead to an increased blending of the object of interest with fainter background objects and this could therefore lead to an increased uncertainty in the radial velocity measurements. As the radiation damage builds over time, the uncertainties will also increase and an analysis of this effect and a possible way to correct for it (linking with OU Euclid and SMILE research), would therefore be of major interest. Impacts of this damage on the astronomy research made possible by Gaia will form the final part of the thesis, linking between the Space Instrumentation and Astronomy research in the School, and will have benefits to other space astronomy missions such as ESAs Euclid and PLATO missions.The outputs of this research would have the added benefit that they would feed into S818: Masters in Space Science and Technology. The Gaia case study, co-written by Andrew Norton and David Hall, provides a link between astronomy and detector technology through teaching. Consideration of the impact of one on the other during the PhD through this cross-disciplinary research would provide further links not only between astronomy and space instrumentation research, but also between the teaching and research in the Masters in Space Science and Technology (S818).