Collaborative Research for DUSEL: Barium tagging in liquid xenon for EXO

EXO是一个利用136-Xe的吨级无中微子双β衰变实验，在此类实验中是独一无二的，因为它采用了一种新颖的技术来标记在双β衰变的最终状态（Ba）中产生的原子种类。这项技术有望大幅减少放射性背景，提供一个干净、明确的测量，具有前所未有的灵敏度。在过去的几年中，EXO的研发工作被平均分配在不带Ba标签的200公斤中型探测器（EXO-200）和Ba标签系统的开发之间。EXO-200的建设现在接近完成。本文的工作主要集中在从液态氙（LXe）中提取Ba和鉴定Ba。本文提出的一些新思路，有可能为全尺寸EXO实验的设计提供关键。先前的研发已经产生了一种离子阱，能够在冷却气体存在的情况下清晰地检测单个Ba离子，并对许多Ba转移技术进行了初步实验。这里提出的研发将围绕三个平行的主题，每个主题将由三个合作机构之一开发。EXO Ba标签研发的结论，以及EXO-200探测器的成功运行，将导致在不久的将来在地下实验室设计一个强大的下一代双β探测器。在这个项目中开发的技术涵盖了广泛的主题，从核和粒子天体物理学到AMO、表面物理学和材料科学。这项研究如果成功，可能适用于其他科学和技术问题，其中对单原子的高效转移和识别将感兴趣。例子包括国土安全应用的痕迹分析和罕见现象的检测。

EXO is a ton-class neutrino-less double beta decay experiment employing 136-Xe and is unique among such experiments as it utilizes a novel technique to tag the atomic species produced in the final state (Ba) of the double beta decay using laser spectroscopy. This technique has the promise of drastically reducing radioactive backgrounds, providing a clean and un-ambiguous measurement with unprecedented sensitivity. In the last few years, EXO R&D has been equally divided between the construction of a 200 kg intermediate scale detector (EXO-200) without Ba tagging and the development of the Ba tagging system. EXO-200 construction is now nearing completion. The work proposed here concentrates on Ba extraction from the liquid xenon (LXe) and identification. Some new ideas, presented here, have the potential of providing the key for the design of the full scale EXO experiment. Previous R&D has resulted in an ion trap capable of clear single Ba ion detection in the presence of a cooling gas, and the initial experimentation with a number of Ba transfer techniques. The R&D proposed here will revolve around three parallel themes, each to be developed by one of the three collaborating institutions. The conclusion of EXO Ba tagging R&D, along with the successful operation of the EXO-200 detector, will result in the design of a formidable next generation double beta detector to be sited at an underground laboratory in the near future. The techniques to be developed in this project span a broad range of topics, from nuclear and particle astrophysics, to AMO, surface physics and material science. This research, if successful, is likely to be applicable to other problems in science and technology, where the high efficiency transfer and identification of single atoms would be of interest. Examples include trace analysis for homeland security applications and the detection of rare phenomena.