A Proposal for the Borexino Solar Neutrino Experiment

calaprica太阳中微子探测器将用于测量太阳内部铍-7衰变产生的中微子通量。这个衰变速率对于理解太阳的能量反应至关重要。探测器是基于使用大约100吨的液体闪烁体来探测探测器体积中中微子-电子相互作用后的反冲电子。大量的光电倍增管阵列将感应由反冲电子在液体闪烁体中产生的光。由于事件发生率极低，将非常注意减少宇宙射线和探测器本身及其周围物质中自然产生的放射性同位素的背景。为了减少宇宙射线背景，探测器将设在地下。场地选择在意大利的格兰萨索地下隧道。这个探测器被称为Borexino，是一个涉及意大利、德国和美国的国际项目。这个实验的结果将测试标准太阳模型，并有助于对中微子的质量进行限制。这些话题是当前的重大科学兴趣，因为早期的结果暗示，由于中微子质量和振荡，太阳中微子通量大幅减少，这被认为发生在太阳中，中微子从一种所谓的风味转变为另一种风味，即从电子中微子转变为μ子或τ中微子。美国国家科学基金会/美国能源部联合核科学咨询委员会在其1996年的长期计划中强调了这一科学。培养学生和博士后是这个实验项目的重要组成部分。本项目由物理学部、天文学部和MPS多学科活动办公室联合支持

***9722552CalapriceA detector of solar neutrinos will be constructed for the purpose of measuring the flux of neutrinos from the decay of beryllium-7 in the solar interior. This decay rate is central to understanding the reactions thought to power the sun. The detector is based on the use of approximately 100 tons of liquid scintillator to detect recoil electrons following neutrino-electron interaction in the detector volume. A large array of photomultiplier tubes will sense the light produced in the liquid scintillator by the recoil electron. Because of the very low rate of events, great attention will be paid to reducing backgrounds from cosmic rays and naturally occurring radioisotopes in the detector proper and the surrounding material. In order to reduce cosmic ray backgrounds, the detector will be located underground. The site chosen is the Gran Sasso underground tunnel in Italy. Construction of this detector, known as Borexino, is an international project involving Italy, Germany, and the US. Results from this experiment will test the standard solar model and help place constraints on the mass of the neutrino. These topics are of great current scientific interest because of earlier results which hint at a substantial reduction in the solar neutrino flux due to neutrino mass and oscillations which are thought to take place in the sun whereby neutrinos change from one so-called flavor into another, i.e. from an electron neutrino into a muon or tau neutrino. The joint NSF/DOE Nuclear Science Advisory Committee highlighted this science in its 1996 Long Range Plan. Education of students and postdocs is a strong component of this experimental program.This project is jointly supported by the Division of Physics, Division of Astronomy and the MPS Office of Multidisciplinary Activities.***