Search for Neutrinoless Double Beta Decay with NEMO-3 and SuperNEMO Experiments

通过 NEMO-3 和 SuperNEMO 实验寻找无中微子双贝塔衰变

• 批准号: 1209920
• 负责人: Karol Lang
• 金额: $ 105.1万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2017-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1209920&HistoricalAwards=false
• 关键词: Search; Neutrinoless; Double; Beta; Decay

Neutrino oscillations not only demonstrate that neutrinos have mass but also imply the existence of new symmetries beyond the Standard Model. Natural conjectures suggest that deeper understanding of neutrinos may provide a glimpse onto phenomena at a Planck-scale energy level, could broaden our knowledge of the fundamental forces, could shed light onto the initial creation of leptons and baryons, and can help to improve our understanding of the early evolution of the Universe. These observations motivate further studies of the properties of neutrinos including investigating if they are Majorana- or Dirac-type. Majorana-type neutrinos lead to a neutrinoless double beta decay -- the second-order weak nuclear process for which an initial state nucleus with atomic weight and number (A, Z) is transformed into a nucleus with (A, Z + 2) with the emission of only two electrons. The two electrons in the final state carry a total energy equal to the energy of the nuclear transition. This seemingly simple principle provides the main observable for detecting neutrinoless double beta decay and poses an experimental challenge in searches for such transitions.This award will provide funding to continue this group's participation in the NEMO-3 data analysis and in the construction of the first SuperNEMO module (the 'Demonstrator'). The NEMO-3 data, collected at the Modane Underground Laboratory under the French-Italian Alps between 2003 and 2011, will be fully analyzed over the next couple of years. For SuperNEMO, the next three years will be a critical period for completing and commissioning the Demonstrator. This group has two new important commitments: to provide the high voltage system for all Demonstrator photomultipliers, and to coordinate the radio-purification of 82-Selenium and production of isotopic foils.Broader Impact: Proving or disproving that neutrinos are Majorana-type may shed light onto the early stages of the evolution of the Universe. This experiment will advance knowledge about some of the rarest phenomena in Nature. On the technical side, the group is developing a unique low background counting technique which may be applied outside of physics and be of general benefit to society. They plan to build on the UT campus an exhibit gallery illustrating the discovery, the underlying physics, and applications of natural radioactivity, cosmic rays, and related subatomic phenomena. It would 'tell a story' that would educate, entertain, fascinate to seek further information, and perhaps steer students or general audience towards the sciences.

中微子的振荡不仅证明了中微子有质量，而且还暗示了标准模型以外新对称性的存在。自然猜想表明，对中微子更深入的理解可能会提供一个普朗克尺度能级的现象一瞥，可以拓宽我们对基本力的知识，可能会揭示轻子和重子的最初创造，并有助于提高我们对宇宙早期演化的理解。这些观测推动了对中微子性质的进一步研究，包括调查它们是马约拉纳类型的还是狄拉克类型的。Majorana类型的中微子导致无中微子的双β衰变--二阶弱核过程，在这个过程中，一个原子量和原子数为(A，Z)的初态核转变为一个只发射两个电子的(A，Z+2)核。处于末态的两个电子携带的总能量等于核跃迁的能量。这一看似简单的原理为探测无中微子双β衰变提供了主要的观测数据，并在寻找这种跃迁方面提出了一个实验挑战。该奖项将为该小组继续参与NEMO-3数据分析和建造第一个超NEMO模块(“演示器”)提供资金。NEMO-3数据是2003年至2011年在法国-意大利阿尔卑斯山下的莫丹地下实验室收集的，将在接下来的几年里进行全面分析。对于SuperNEMO来说，未来三年将是完成和调试示威器的关键时期。该小组有两个新的重要承诺：为所有示例性光电倍增管提供高压系统，以及协调82-硒的放射性提纯和同位素薄片的生产。更广泛的影响：证明或反驳中微子是马约拉纳型中微子可能有助于揭示宇宙演化的早期阶段。这项实验将增进人们对自然界一些最稀有现象的了解。在技术方面，该小组正在开发一种独特的低本底计数技术，该技术可能应用于物理学之外，并对社会普遍有益。他们计划在德克萨斯大学园区建造一个展览馆，展示天然放射性、宇宙射线和相关亚原子现象的发现、基本物理和应用。它将讲述一个故事，它将教育、娱乐、吸引人们寻找进一步的信息，或许还会引导学生或普通观众走向科学。