Enriched Xenon Observatory for double beta decay

富集氙天文台（EXO）合作致力于寻找中微子双β衰变(0？136Xe的ß)。对这种衰变的观察将证明中微子是它们自己的反粒子（Majorana），提供关于中微子质量的尺度和顺序的信息，并提供轻子数不守恒的第一个证据。EXO目前在新墨西哥州卡尔斯巴德附近运行一个富集氙液相时间投影室（EXO200）。利用从这个实验中收集的数据，EXO首次测量了136Xe的常规双β衰变，并在寻找中微子衰变方面产生了世界领先的测量结果。加拿大团队为这些努力做出了重大贡献，为项目提供了硬件和分析专业知识。例如，加拿大人在探测器设计和工程、校准系统和分析协调方面承担了主要责任。Jacques Farine教授（Laurentian）目前担任EXO科学委员会主席，David Sinclair教授（Carleton）担任EXO执行委员会成员。EXO200将在至少2年的时间里继续收集数据，并有望继续走在寻找暗物质的前沿。ßß衰变。在搜索0？在EXO200之后，EXO将有必要扩大其探测器技术并降低背景电平。基于EXO200的成功，双方正在合作开发下一代液相检测器（nEXO）。随着TRIUMF集团加入EXO，加拿大人有能力领导EXO下一阶段发展的重要组成部分。这项工作将包括校准系统的设计、紫外敏感光探测器的评估、蒙特卡罗模拟、探测器工程和钡标记的持续发展。SNOLAB的“cryopit”可以为EXO的下一阶段提供一个绝佳的家，合作正在为nEXO追求这一概念。虽然液相检测器可能是下一个EXO规模的最佳选择，但气相检测器可能具有明显的优势。因此，加拿大团队将继续进行探测器的研发，特别是气相可能性的钡标记。

The Enriched Xenon Observatory (EXO) collaboration is engaged in a search for the neutrinoless double beta decay (0?ßß) of 136Xe. Observation of this decay would prove that neutrinos are their own anti-­-pariticle (Majorana), provide information on the scale and ordering of neutrino masses, and give the first evidence for lepton number non-­-conservation. EXO is currently operating an enriched xenon liquid-­-phase time projection chamber (EXO200) near Carlsbad, New Mexico. With data collected from this experiment, EXO made the first measurement of the regular double beta decay of 136Xe and has produced world-­-leading measurements in the search for the neutrinoless decay. Canadian groups have contributed significantly to these efforts providing both hardware and analysis expertise to the project. For example, Canadians have taken lead responsibility for elements of detector design and engineering, calibration systems, and analysis coordination. Prof. Jacques Farine (Laurentian) is currently chair of the EXO Scientific Board and Prof. David Sinclair (Carleton) is serving on the EXO Executive Committee. EXO200 will continue collecting data for at least 2 more years and expects to remain at the forefront of the search for the 0?ßß decay. To substantially improve sensitivity in the search for 0?ßß beyond EXO200, it will be necessary for EXO to scale up its detector technology and decrease the background levels. Based on the success of EXO200, the collaboration is pursuing development of a next-­-generation liquid-­-phase detector (nEXO). With the addition of the TRIUMF group to EXO, the Canadians are well-­-positioned to lead significant components in the development of the next phase of EXO. This work will include design of calibration systems, evaluation of UV sensitive photo-­-detectors, Monte Carlo simulation, detector engineering, and continued Barium tagging development. The SNOLAB ‘cryopit’ could provide an excellent home for this next phase of EXO, and the collaboration is pursuing concepts for nEXO with this in mind. While a liquid-­-phase detector might prove the best option for the next scale of EXO, there are distinct advantages that might be gained from a gas-­-phase detector. Hence the Canadian groups will continue to pursue detector R&D and, in particular, barium tagging for the gas-­-phase possibility.