Probing the Majorana Nature of Neutrinos with KamLAND-Zen

使用 KamLAND-Zen 探测中微子的马约拉纳性质

• 批准号: 2310130
• 负责人: Christopher Grant
• 金额: $ 48万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2310130&HistoricalAwards=false
• 关键词: Probing; Majorana; Nature; Neutrinos; KamLAND

Neutrinos are electrically neutral, weakly interacting, subatomic particles and are one of the most abundant particles in the universe. Our understanding of the fundamental nature of neutrinos has rapidly progressed in recent decades, yet we are still unable to some very basic questions. What is the absolute mass of the neutrino? Why are neutrino masses so small compared to other elementary particles? How did the neutrino obtain a mass? The answers to these questions could be intimately related to the neutrino being its own antiparticle, known as a Majorana particle, and might also explain the absence of anti-matter in the universe. The PI will shed light on these questions by searching for a hypothetical nuclear process called neutrinoless double beta decay. An observation of this process would provide direct proof that neutrinos are Majorana particles; however, it will be extremely difficult to observe due to the vast number of very similar processes constantly taking place inside experiments. A competitive search requires a large quantity of double beta decay isotope and exquisite suppression of backgrounds. Therefore, the PI will upgrade the world-leading neutrinoless double beta decay experiment, KamLAND-Zen, with state-of-the-art data acquisition electronics and novel machine learning algorithms. This exciting area of experimental research will provide an excellent platform for training students and postdocs in advanced technical skills that are highly sought-after in in academia, industry, and national laboratories. In the last year, KamLAND-Zen (a liquid scintillator detector in Japan loaded with Xe-136) began searching for neutrinoless double beta decay in new regions of phase space for the first time. The PI is implementing major enhancements to KamLAND-Zen while continuing to collect and analyze new data. The first enhancement involves a state-of-the-art deep learning algorithm recently developed by the PI, called KamNET, which will be used to search for the elusive two-neutrino double beta decays of Xe-136 excited states. The PI will also use KamNET to perform a combined analysis over all present and past KamLAND-Zen data to maximize its sensitivity to neutrinoless double beta decay. The second enhancement involves the installation and commissioning of zero dead-time waveform digitizer electronics with online event tagging logic, known as MoGURA2. MoGURA2 will be used to reduce the leading backgrounds in the search for neutrinoless double beta decay on KamLAND-Zen.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

中微子是一种电中性、弱相互作用的亚原子粒子，是宇宙中含量最丰富的粒子之一。近几十年来，我们对中微子基本性质的认识取得了快速进展，但我们仍然无法回答一些非常基本的问题。中微子的绝对质量是多少？为什么与其他基本粒子相比，中微子的质量这么小？中微子是如何获得质量的？这些问题的答案可能与中微子是它自己的反粒子密切相关，被称为Majorana粒子，也可能解释为什么宇宙中没有反物质。PI将通过寻找一种被称为无中微子双β衰变的假想核过程来阐明这些问题。对这一过程的观察将直接证明中微子是马约拉纳粒子；然而，由于在实验中不断发生大量非常相似的过程，观察将极其困难。竞争性搜索需要大量的双β衰变同位素和精致的背景抑制。因此，PI将升级世界领先的无中微子双β衰变实验KamLAND-Zen，配备最先进的数据采集电子设备和新颖的机器学习算法。这一激动人心的实验研究领域将为培训学生和博士后掌握高级技术技能提供一个极好的平台，这些技能在学术界、工业界和国家实验室都非常受欢迎。去年，日本的一台装有Xe-136的液体闪烁体探测器KamLAND-Zen首次开始在相空间的新区域寻找无中微子双β衰变。PI正在对KamLAND-Zen进行重大改进，同时继续收集和分析新数据。第一个改进涉及PI最近开发的一种最先进的深度学习算法，称为KamNET，它将用于搜索Xe-136激发态的难以捉摸的双中微子双β衰变。PI还将使用KamNet对所有现在和过去的KamLAND-ZEN数据进行综合分析，以最大限度地提高其对无中微子双β衰变的敏感度。第二项改进包括安装和调试具有在线事件标记逻辑(称为MoGURA2)的零死区波形数字化仪电子设备。MoGURA2将被用来减少在卡姆兰德-ZEN上寻找无中微子双β衰变的领先背景。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。