Neutrino Physics: Solar - Borexino

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告诉我们太阳内部运作的时代。碳-氮-氧（CNO）循环是恒星将氢转化为氦并释放电子-中微子的聚变反应之一。如果下一个周期允许Borexino探测器足够好地测量CNO中微子通量，以推断太阳内部的金属丰度（氢或氦以外元素的丰度），它可以测试太阳均匀性的基本假设，并提供关于太阳内部不透明的关键信息，这对日震学很重要。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学的理解产生重大影响。该奖项为弗吉尼亚理工大学在Borexino实验中的持续作用提供了资金，Borexino实验是位于意大利格兰萨索国家实验室的世界上最纯净的大体积液体闪烁体探测器，旨在测量来自太阳的中微子光谱的主要成分，因为它通过聚变将氢转化为氦。他们测量了来自太阳的7-Be、8-B和pep中微子通量，并设定了CNO中微子通量的极限。接下来的三年超低背景期需要重新校准以验证这些结果，并为进入新的“以CNO为重点”阶段的合作做好准备。主要的物理目标是1)测量CNO中微子通量，2)更精确地测量7-Be和pep中微子通量，3)更好地测量pp中微子通量。该计划对科学、技术和推广的更广泛影响包括：培养当前主题物理研究的研究生和本科生；具有超净校准技术的部署和使用经验；通过研究项目、学生报告、讲座和问题向本科生展示这一研究计划——让来自多个领域的下一代科学家接触到令人兴奋的天体粒子物理学；并通过他们的中微子物理中心广泛参与中微子社区。

Solar neutrino research has already discovered massive neutrinos and flavor mixing, and is moving into an era where precision measurements can tell us about the inner workings 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. Should this next period allow the Borexino detector to measure the CNO neutrino flux sufficiently well to infer the metallicity (the abundance of elements other than hydrogen or helium) of the sun's interior, 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. This award provides funding for the continuing role of Virginia Tech in the Borexino experiment, the world's purest large-volume liquid scintillator detector located at the Gran Sasso National Laboratory in Italy, designed to measure the principle components of the neutrino spectrum coming from the Sun as it converts hydrogen into helium through fusion. They have measured the 7-Be, 8-B, and pep neutrino fluxes from the Sun, and set a limit on the CNO neutrino flux. The next three-year period with ultra-low background requires re-calibration to verify these results, and to prepare the collaboration to move into a new 'CNO focused' phase. The principle physics goals are 1) measurement of the CNO neutrino flux, 2) more precise results for the 7-Be and pep neutrino flux, and 3) a better result for the pp neutrino flux. The broader impact on science, technology and outreach that is expected from the program includes: the training of graduate and undergraduate students in current topical physics research; experience with deployment and utilization of ultra-clean calibration techniques; presentations of this research program to undergraduates, through research projects, student presentations, lectures, and problems - exposing the next generation of scientists from multiple fields to the excitement of astroparticle physics; and a broad engagement of the neutrino community through their Center for Neutrino Physics.