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

太阳中微子研究已经发现了大量的中微子和味道混合，并正在进入一个精确测量可以提供一个独特的探测器太阳的结构和组成的时代。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中微子的流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中的太阳金属丰度(氢或氦以外的元素的丰度)。它可以检验太阳同质性的基本假设，并提供有关太阳内部不透明的关键信息，这些信息对日震学很重要。因此，这样的研究可能会对我们对太阳、恒星天体物理学、行星和恒星形成之间的联系，以及基本的中微子物理的理解产生重大影响。Borexino是一种液体闪烁体探测器，位于意大利Gran Sasso国家实验室，对太阳中微子具有独特的敏感性。Borexino研究项目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当务之急。该组织通过普林斯顿大学的女性物理学奖积极促进女性从事科学研究。该奖项为普林斯顿大学的小组提供资金，以继续提高敏感度并协助Borexino探测器的操作。Borexino对太阳中微子的敏感性主要是因为在液体闪烁体中通过重新净化降低了背景后，可以获得极低的本底。净化操作的方法和设备由普林斯顿大学提供，管理操作的工作人员也是如此。进一步减少闪烁体背景是可能的，通过适度改进净化系统，以及计划在这里进行更多的闪烁体净化操作。有了这些变化，Borexino将处于有利地位，可以对CNO中微子进行首次测量。更低本底的未来数据也将改进早先对pp、pep、Be-7和B-8中微子的Borexino测量。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-物质效应依赖关系，以及寻找非标准相互作用。

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.