CAREER: Maximizing the Science Output of EXO-200

中微子是宇宙中最神秘的亚原子粒子之一。最近在中微子振荡实验中取得的突破揭示了它们的质量很小，并提出了几个有趣的问题。为什么中微子比其他粒子轻得多？中微子质量的绝对尺度是多少？中微子是它们自己的反粒子吗？解决这些问题的关键可能在于寻找一种非常罕见的衰变过程，称为中微子双β衰变。在这种衰变过程中，原子核内的两个中子同时衰变为两个质子，释放出两个电子而不释放中微子。该项目的目标是利用EXO-200实验的数据对这种罕见的衰变进行最敏感的搜索之一。如果发现这种难以捉摸的衰变，就意味着中微子本身就是反粒子；因此，中微子获得质量的方式与其他粒子不同。这一结果也可能揭示为什么宇宙中物质多于反物质的奥秘。除了对中微子的研究外，首席研究员还将制定一项教育计划，以加强中学水平的科学教育。具体而言，PI将与伊利诺伊大学厄巴纳-香槟分校的教育学院合作举办中学物理科学教学研讨会，并通过一系列创新的外展活动，在伊利诺伊州的中学生和科学专业之间建立更紧密的联系。该项目将围绕新型分析技术的发展进行研究、推广和教育，以提高EXO-200等大型液态氙探测器的性能。EXO-200在第一阶段的运行中，展示了大型液态氙探测器在寻找Xe-136中的中微子双β衰变方面的独特能力。随着2016年探测器的升级和三年的第二阶段额外运行，EXO-200可以将其对Xe-136中微子双β衰变半衰期的灵敏度提高三倍。这项工作的重点是开发新的分析技术，以提高探测器的能量分辨率和提高其背景抑制能力，这对于最大限度地提高EXO-200的物理到达能力至关重要。了解和演示EXO-200的最终性能可以为未来吨级探测器的设计提供必要的输入。所开发的分析技术也可以应用于粒子物理实验和医学成像的大型贵重液体探测器。与此同时，计划开展教育和推广活动，以加强中学科学教育。PI将与伊利诺斯州的同事一起为地区中学教师组织研讨会，讨论根据新一代科学标准进行的物理科学教学，并开展实践课堂活动以实施新标准。PI还将指导大学生志愿者通过示范、在线论坛和协助学校发起的科学项目，向中学生提供服务。

Neutrinos are among the most mysterious sub-atomic particles in the Universe. Recent breakthroughs in neutrino oscillation experiments have revealed that they have tiny masses and have raised several intriguing questions. Why are neutrinos so much lighter than the other particles? What is the absolute scale of the neutrino masses? And are the neutrinos their own antiparticles? The keys to addressing these questions may lie in the search for a very rare decay process called neutrinoless double beta decay. During such a decay, two neutrons inside a nucleus simultaneously decay into two protons, emitting two electrons and no neutrino. The goal of the project is to perform one of the most sensitive searches of this rare decay using data from the EXO-200 experiment. A discovery of this elusive decay would signify that neutrinos are their own antiparticles; thus neutrinos obtain their masses differently from other particles. The results may also shed light on the mystery of why there is more matter than anti-matter in the Universe. In addition to his research on neutrinos, the principal investigator will also develop an educational program to strengthen science education at the middle-school level. Specifically, the PI will organize workshops on middle-school physical science teaching in collaboration with the College of Education at the University of Illinois at Urbana-Champaign and build closer connections between middle-school students and science majors at Illinois through a series of innovative outreach activities.The project will integrate research, outreach, and education around the development of novel analysis techniques to enhance the performance of large liquid xenon detectors such as EXO-200. In its Phase-I operation, EXO-200 has demonstrated the unique capability of large liquid xenon detectors in the search for neutrinoless double beta decay in Xe-136. With detector upgrades in 2016 and three years of additional Phase-II running, EXO-200 can improve by threefold its sensitivity to the Xe-136 neutrinoless double beta decay half-life. The work focuses on the development of new analysis techniques to enhance the detector energy resolution and improve its background rejection capabilities, which are essential for maximizing the physics reach of EXO-200. Understanding and demonstrating the ultimate performance of EXO-200 can provide essential inputs to the design of future tonne-scale detectors. The analysis techniques to be developed can also be applied to large noble liquid detectors for particle physics experiments and medical imaging. In parallel, educational and outreach activities are planned to enhance middle school science education. The PI together with colleagues at Illinois will organize workshops for area middle school teachers on physical science teaching in accordance with the New Generation Science Standards and the development of hands-on classroom activities to implement the new standards. The PI will also direct undergraduate volunteers in outreach to middle school students through demonstrations, an online forum, and assisting in school-initiated science programs.