Low Energy Nuclear Physics at Princeton - The Borexino Solar Neutrino Experiment

普林斯顿大学的低能核物理 - Borexino 太阳中微子实验

• 批准号: 0201141
• 负责人: Frank Calaprice
• 金额: $ 230.01万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-01 至 2006-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0201141&HistoricalAwards=false
• 关键词: Low; Energy; Nuclear; Physics; Princeton

Borexino is a new solar neutrino experiment that will use 300 tons ofhigh purity liquid scintillator to measure the low energy part of thesolar neutrino spectrum (E 1MeV). More than 30 years of experimentshave shown that fewer solar neutrinos are detected than expected fromthe nuclear fusion reactions that power the sun. Recent experimentsindicate that the discrepancy is due to "neutrino oscillations", aprocess in which neutrinos produced in the sun as "electron-neutrinos",oscillate to a non-electron-neutrino state. The oscillation process ispossible if neutrinos do indeed have a finite mass, rather than a zeromass, as is the case in the present standard model of elementaryparticles. If oscillations are confirmed, and neutrinos have mass, theresult would be a major departure from our current understanding ofelementary particle, with important implications in physics andastronomy. The latest experimental data of the Sudbury Neutrino Observatory,together with the SuperK experiment, provide the most convincingevidence that neutrinos are oscillating. The interpretation of theseand other data in the Mikheyev-Smirnov-Wolfenstein theoretical frameworkindicates that oscillation effects for neutrinos below 1 MeV could bedramatic. One observational possibility is a large day/night asymmetryin count rate for low energy neutrinos. Borexino is designed to measurethe 0.86 MeV 7Be neutrinos and is thus well positioned to explore thisunique low energy neutrino oscillation effect. The Borexino detector is located in the Gran Sasso undergroundlaboratory in Italy. The low background requirements necessary fordetecting 7Be neutrinos pose formidable technical challenges. Afterseveral years of R&D with a prototype detector, and four years ofconstruction, Borexino is expected to become operational in 2002. Theobjective of this proposal in the two-year period 2002-2004 is tocomplete the commissioning and start-up phase of Borexino and begintaking solar neutrino data. This proposal will support the PrincetonUniversity Group in completing and operating the muon detector and thescintillator purification, filling, and containment subsystems of thedetector. It will also support the early stages of data acquisition anddata analysis.

Borexino是一项新的太阳中微子实验，将使用300吨高纯度液体闪烁体来测量太阳中微子光谱的低能部分（E 1MeV）。 30多年的实验表明，从为太阳提供动力的核聚变反应中检测到的太阳中微子比预期的要少。 最近的实验表明，这种差异是由于“中微子振荡”造成的，在这个过程中，太阳中产生的中微子作为“电子中微子”振荡到非电子中微子状态。 如果中微子确实具有有限质量，而不是像当前基本粒子标准模型中的零质量，则振荡过程是可能的。 如果振荡得到证实，并且中微子具有质量，结果将与我们目前对基本粒子的理解产生重大背离，对物理学和天文学具有重要意义。萨德伯里中微子天文台的最新实验数据与SuperK实验一起，提供了中微子振荡的最有说服力的证据。 Mikheyev-Smirnov-Wolfenstein 理论框架中对这些数据和其他数据的解释表明，低于 1 MeV 的中微子的振荡效应可能是巨大的。 一种观察到的可能性是低能中微子计数率存在较大的昼/夜不对称性。 Borexino 旨在测量 0.86 MeV 7Be 中微子，因此能够很好地探索这种独特的低能中微子振荡效应。 Borexino探测器位于意大利格兰萨索地下实验室。 检测 7Be 中微子所需的低背景要求带来了巨大的技术挑战。 经过几年的原型探测器研发和四年的建设，Borexino 预计将于 2002 年投入运行。该提案的目标是在 2002-2004 年两年期间完成 Borexino 的调试和启动阶段，并开始获取太阳中微子数据。 该提案将支持普林斯顿大学集团完成和运行μ子探测器以及探测器的闪烁体净化、填充和遏制子系统。 它还将支持数据采集和数据分析的早期阶段。