A Proposal for the Borexino Solar Neutrino Experiment

* 9722552中微子将建造一个太阳中微子探测器，用于测量太阳内部铍-7衰变产生的中微子通量。 这种衰变率是理解太阳能反应的核心。 该探测器是基于使用约100吨的液体闪烁体，以检测反冲电子后，中微子-电子在探测器体积的相互作用。 一个大型的光电倍增管阵列将检测液体闪烁体中由反冲电子产生的光。由于事件发生率非常低，因此将非常注意减少探测器本身和周围材料中来自宇宙射线和自然存在的放射性同位素的背景。 为了减少宇宙射线背景，探测器将位于地下。 选址是意大利的格兰萨索地下隧道。 这个探测器的建造被称为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，并帮助限制中微子的质量。 这些课题是当前科学界非常感兴趣的，因为早期的结果暗示，由于中微子质量和振荡，太阳中微子通量会大幅减少，而这些振荡被认为是在太阳中发生的，中微子从一种所谓的味道变成另一种，即从电子中微子变成μ子或τ中微子。 NSF/DOE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。 学生和博士后的教育是这个实验计划的一个重要组成部分。该项目由物理学系，天文学系和MPS多学科活动办公室共同支持。*

***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.***