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

欧空局盖亚使命于2013年12月启动，其雄心勃勃的目标是在其5年（加上1-4年的延长）寿命内绘制惊人的10亿个天文物体。Gaia焦平面由106个定制设计的e2 v CCD组成。探测器在轨道上受到辐射损坏，迄今为止的结果表明，这种损坏比发射前预测的要低得多，造成这种较低程度损坏的因素尚未得到证实，尽管有几个可能的原因。一个是来自挡板末端的纤维和冰的光散射的增加的光学背景。另一个问题是，在轨辐照的设备温度比发射前测试活动低100 K以上。目前的研究表明，这两个因素对所收到的损害程度有重大影响。为欧空局欧几里得使命任务开发的模拟使用了类似的探测器（Skottfelt），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学方面显示出很大的希望。虽然发射前对盖亚辐射活动数据（霍尔和干燥器）的研究已经结束，但数据现在正在从轨道返回。利用这些信息，除了开发盖亚探测器的模拟器，学生将能够获得真实的信息的陷阱发展中的CCD在轨，反馈这些信息到其他使命研究（如欧几里得，SMILE，WFIRST等）。学生将继续看看辐射损伤将如何影响盖亚RVS输出从天文学角度在使命（诺顿）。CCD辐射损坏造成的模糊可导致感兴趣物体与较暗背景物体的混合增加，因此可导致径向速度测量的不确定性增加。随着时间的推移，辐射损害的积累，不确定性也将增加，因此，对这种影响的分析以及纠正这种影响的可能方法（与Euclid欧几里得和SMILE研究相联系）将是主要的兴趣。这一损害对天文学研究的影响可能由盖亚将形成论文的最后一部分，空间仪器和天文学研究之间的联系在学校，并将有好处的其他空间天文任务，如欧空局欧几里得和柏拉图的任务。这项研究的产出将有额外的好处，他们将饲料S818：在空间科学和技术硕士。由安德鲁·诺顿和大卫·霍尔共同撰写的盖亚案例研究通过教学提供了天文学和探测器技术之间的联系。通过这种跨学科的研究，在博士学位期间考虑一个对另一个的影响，不仅将提供天文学和空间仪器研究之间的进一步联系，而且还将提供空间科学与技术硕士学位（S818）的教学和研究之间的联系。

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).