Neutrino-less Double-Beta Decay with CUORE and the MAJORANA DEMONSTRATOR

使用 CUORE 和 MAJORANA DEMONSTRATOR 进行无中微子双贝塔衰变

• 批准号: 1614611
• 负责人: Frank Avignone
• 金额: $ 90万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-01 至 2021-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1614611&HistoricalAwards=false
• 关键词: Neutrino; less; Double; Beta; Decay

This grant partially supports neutrino research at the University of South Carolina (USC). The group studies the properties of the neutrino, the most prolific particle in the universe, about which much is still unknown. The primary effort is the search for the hypothesized, but not yet discovered, nuclear-radioactive decay called zero-neutrino double-beta decay. The existence of such a radioactive decay mode has important consequences. Its existence requires that neutrinos have mass, and that they are their own anti-particles. Most importantly, this process would require the violation of an important fundamental conservation law of elementary particle physics. The USC group has leadership roles in two of the leading experiments in this field: the MAJORANA DEMONSTRATOR, in the Sanford Underground Research Facility in South Dakota, and the Cryogenic Underground Observatory (CUORE) in the Laboratori Nazionali del Gran Sasso (LNGS) in Italy. The spin-off technology from the required radiopurity of materials for the ultra-low background detectors has transitioned directly into Homeland Security. Four past USC PhD students from the program hold important positions in Homeland Security, at the Pacific Northwest and Savannah River National Laboratories. CUORE, nearing completion in the LNGS, is an array of 988 tellurium oxide single-crystal bolometers that operate at ~8-10 mK to search for the zero-neutrino decay of tellurium-130 (Te-130); the detector will contain 200-kg of Te-130. The predicted half-life sensitivity is ~10^(26) years, to reach into the inverted hierarchy neutrino-mass region. USC leads part of the R&D to determine the feasibility and cost of enriching CUORE to 93% in Te-130 from 33.4%, and equipping the bolometers with Cherenkov-light detectors to discriminate against alpha-particle background. These upgrades are designed to reach the sensitivity required to cover the inverted neutrino mass hierarchy. USC leads the CUORE data analysis to search for zero-neutrino double-beta decay of Te-130 to the first excited 0+ state in xenon-130, by detecting the coincidence events from the two electrons and cascade gamma rays. This technique achieved zero-background in the prototype experiment, CUORICINO. Finally, the USC group was responsible for the production of the CUORE front-end electronics, and will participate in its installation, commissioning and maintenance.

这项拨款部分支持了南卡罗来纳州大学的中微子研究。 该小组研究宇宙中最多产的粒子中微子的性质，但对中微子仍有许多未知之处。主要的努力是寻找假设的，但尚未发现的，称为零中微子双β衰变的核放射性衰变。这种放射性衰变模式的存在具有重要的后果。它的存在要求中微子具有质量，并且它们是自己的反粒子。最重要的是，这个过程需要违反基本粒子物理学的一个重要的基本守恒定律。 南加州大学集团在这一领域的两个领先实验中发挥了领导作用：南达科他州桑福德地下研究设施的MAJORANA DEMONSTRATOR，以及意大利大萨索国立科学院（LNGS）的低温地下观测站（CUORE）。 从超低背景探测器所需材料的放射性纯度中衍生出来的技术已经直接过渡到国土安全部。 四名来自该计划的南加州大学博士生在太平洋西北部和萨凡纳河国家实验室的国土安全部担任重要职务。在LNGS中即将完成的CUORE是一个由988个氧化碲单晶测辐射热计组成的阵列，其工作温度约为8-10 mK，用于搜索碲-130（Te-130）的零中微子衰变;探测器将包含200公斤的Te-130。预测的半衰期灵敏度为~10^（26）年，以达到中微子质量的倒层次区域。南加州大学领导了部分研发工作，以确定将CuORE从33.4%的Te-130浓缩到93%的可行性和成本，并为测辐射热计配备切伦科夫光探测器以区分α粒子背景。这些升级旨在达到覆盖倒置中微子质量等级所需的灵敏度。USC领导CUORE数据分析，通过探测来自两个电子和级联伽马射线的符合事件，寻找Te-130到氙-130中第一激发0+态的零中微子双β衰变。该技术在原型实验CUORICINO中实现了零背景。最后，南加州大学集团负责CUORE前端电子设备的生产，并将参与其安装、调试和维护。