Systematic improvement of 39Ar Atom Trap Trace Analysis and its application to derive a millennial palaeotemperature record from groundwater

稀有气体放射性同位素39Ar是独特的，因为它是唯一覆盖50至1000年重要年龄范围的同位素。因此，它对海洋学，冰川学和水文地质学的定年具有很大的兴趣。原子阱痕量分析（ATTA）的发展使81Kr测年成为可能，并有可能从根本上开辟39Ar的新应用。在之前的一个项目中，我们首次证明了ATTA对自然样品进行39Ar分析是可能的。在前一个项目积累的经验和额外的初步工作的基础上，本项目将为39Ar的ATTA （ArTTA）作为同位素水文学的新工具奠定知识和工具基础。我们的目标是将ArTTA从原理验证阶段推进到一个完全建立的方法，并进行其首次全面应用。基于地下水和古气候研究的现有专业知识，并利用地下水作为ArTTA试验平台的优势，我们计划从地下水中获得过去一千年的第一个详细的古温度记录。我们确定了以下两个中心目标：显著提高了ArTTA装置的效率。提高计数率是提高样品通量和可实现的测量精度的必要条件。2. 首次完成ArTTA对地下水39ar定年的完整研究，在世纪尺度上评估地下水年龄分布和古气候演化。

The noble gas radioisotope 39Ar is unique, as it is the sole isotope to cover the important age range of about 50 to 1000 yr. Hence it is of great interest for dating in oceanography, glaciology, and hydrogeology. The development of Atom Trap Trace Analysis (ATTA) has rendered 81Kr dating possible and has the potential to open up fundamentally new applications of 39Ar. In a previous project we have for the first time demonstrated that 39Ar analysis of natural samples by ATTA is possible. Building on the experience gathered in that previous project and additional preliminary work, the present project shall create the intellectual and instrumental foundations of ATTA for 39Ar (ArTTA) as a new tool in isotope hydrology. We aim at advancing ArTTA from the proof-of-principle stage to a fully established method and to conduct its first comprehensive application. Based on the available expertise in groundwater and palaeoclimate research and using the advantages of groundwater as a testbed for ArTTA, we plan to derive the first detailed palaeotemperature record for the past millennium from groundwater. We have identified the following two central objectives: 1. Significant improvement of the efficiency of the ArTTA device. Enhancing the count rate is necessary to improve the sample throughput as well as the achievable measurement precision. 2. Realization of the first complete study of 39Ar-dating of groundwater by ArTTA, in order to assess groundwater age distributions and palaeoclimate evolution on the timescale of centuries.