CNO Solar Neutrinos with Borexino - A Quest For Ultra-Low Background

CNO 太阳中微子与 Borexino——对超低背景的探索

• 批准号: 1506378
• 负责人: Frank Calaprice
• 金额: $ 132.3万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506378&HistoricalAwards=false
• 关键词: CNO; Solar; Neutrinos; Borexino; Quest

Solar neutrino research has already discovered massive neutrinos and flavor mixing and is moving into an era where precision measurements can provide a unique probe of the structure and composition of the Sun. The carbon-nitrogen-oxygen (CNO) cycle is one of the fusion reactions by which stars convert hydrogen to helium, releasing electron-neutrinos. The CNO neutrino flux depends on the abundance of carbon in the core of the Sun. A measurement of the CNO flux would be the first direct measurement of the solar metallicity (the abundance of elements other than hydrogen or helium) in the core of the Sun. It could test the fundamental assumption of homogeneity in the Sun and provide crucial information regarding opacities in the solar interior that are important for helioseismology. Such studies could thus have a great impact on our understanding of the Sun, stellar astrophysics, the link between planetary and stellar formation, as well as basic neutrino physics. Borexino is a liquid scintillator detector, located at the Gran Sasso National Laboratory in Italy, with a unique sensitivity to solar neutrinos.The Borexino research program has involved many undergraduate and graduate students. Mentoring and training these younger researchers from Princeton and other schools is a high priority. The group is actively promoting women in science through Princeton Women in Physics.This award provides funding for the Princeton U. group to continue to improve the sensitivity and to assist in the operation of the Borexino detector. Borexino's sensitivity to solar neutrinos is due primarily to the extremely low background made possible after reducing backgrounds in the liquid scintillator by re-purification. The methods and equipment for purification operations were provided by Princeton, as was the staff that managed the operations. Further reduction of the scintillator background is possible with modest improvements of the purification system and with the additional scintillator purification operations planned here. With these changes, Borexino will be in a good position to make the first measurement of CNO neutrinos. Future data with lower background will also result in improvements of the earlier Borexino measurements of pp, pep, Be-7, and B-8 neutrinos. The future measurement of all solar neutrinos will map out with higher sensitivity the vacuum-to-matter-effect dependence of neutrino oscillations on the neutrino energy, as well as search for non-standard interactions.

太阳中微子研究已经发现了大量的中微子和味道混合，并且正在进入一个精确测量可以提供太阳结构和组成的独特探测的时代。碳-氮-氧（CNO）循环是恒星将氢转化为氦，释放电子中微子的聚变反应之一。CNO中微子通量取决于太阳核心中碳的丰度。对CNO通量的测量将是第一次直接测量太阳核心的金属丰度（氢或氦以外的元素丰度）。它可以检验太阳均匀性的基本假设，并提供关于太阳内部不透明性的关键信息，这对日震学很重要。因此，这些研究可能对我们理解太阳、恒星天体物理学、行星和恒星形成之间的联系以及基本中微子物理学产生重大影响。Borexino是一种液体闪烁体探测器，位于意大利的Gran Sasso国家实验室，对太阳中微子具有独特的灵敏度。Borexino研究计划涉及许多本科生和研究生。指导和培训这些来自普林斯顿和其他学校的年轻研究人员是一个高度优先事项。该组织通过“普林斯顿女性物理学奖”积极促进女性在科学领域的发展。小组继续提高灵敏度，并协助Borexino探测器的操作。Borexino对太阳中微子的敏感性主要是由于通过再纯化减少液体闪烁体中的背景后，使其具有极低的背景。净化操作的方法和设备都是普林斯顿提供的，管理操作的人员也是普林斯顿提供的。通过对净化系统进行适度改进，并在此计划进行额外的闪烁体净化操作，可以进一步降低闪烁体背景。有了这些变化，Borexino将能够首次测量CNO中微子。未来的数据与较低的背景也将导致改进的早期Borexino测量的pp，pep，Be-7，和B-8中微子。未来对所有太阳中微子的测量将以更高的灵敏度绘制出中微子振荡对中微子能量的真空-物质效应依赖性，以及寻找非标准相互作用。