Geo-neutrino results with Borexino

[摘要] Borexino is a liquid scintillator detector primary designed to observe solar neutrinos. Due to its low background level as well as its position in a nuclear free country, Italy, Borexino is also sensitive to geo-neutrinos. Borexino is leading this interdisciplinary field of neutrino geoscience by studying electron antineutrinos which are emitted from the decay of radioactive isotopes present in the crust and the mantle of the Earth. With 2056 days of data taken between December 2007 and March 2015, Borexino observed 77 antineutrino candidates. If we assume a chondritic Th/U mass ratio of 3.9, the number of geo-neutrino events is found to be 23.7+6.5-5.7(stat)+0.9-0.6(syst). With this measurement, Borexino alone is able to reject the null geo-neutrino signal at 5.9σ, to claim a geo-neutrino signal from the mantle at 98% C.L. and to restrict the radiogenic heat production for U and Th between 23 and 36 TW.

[发布机构] INFN Laboratori Nazionali Del Gran Sasso, Assergi (AQ); 67010, Italy^1;AstroParticule et Cosmologie, Universite Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cite, Paris, Cedex; 75205, France^2;Physik-Department and Excellence Cluster Universe, Technische Universitat Miinchen, Garching; 85748, Germany^3;Dipartimento di Fisica, Universita degli Studi e INFN, Milano; 20133, Italy^4;Chemical Engineering Department, Princeton University, Princeton; NJ; 08544, United States^5;Institut fur Experimentalphysik, Universitat, Hamburg; 22761, Germany^6;Physics Department, Virginia Polytechnic Institute, State University, Blacksburg; VA; 24061, United States^7;Physics Department, Princeton University, Princeton; NJ; 08544, United States^8;Dipartimento di Fisica, Universita degli Studi e INFN, Genova; 16146, Italy; (10) Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow; 119234, Russia; (11) Gran Sasso Science Institute (INFN), L'AQUILA; 67100, Italy; (12) NRC Kurchatov Institute, Moscow; 123182, Russia; (13) Joint Institute for Nuclear Research, Dubna; 141980, Russia; (14) Department of Physics, University of Houston, Houston; TX; 77204, United States; (15) M. Smoluchowski Institute of Physics, Jagiellonian University, Krakow; 30059, Poland; (16) Kiev Institute for Nuclear Research, Kiev; 06380, Ukraine; (17) Department of Physics, Technische Universität Dresden, Dresden; 01062, Germany; (18) National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe highway 31, Moscow; 115409, Russia; (19) Max-Planck-Institut fur Kernphysik, Heidelberg; 69117, Germany; (20) Dipartimento di Fisica e Scienze della Terra Universitádegli Studi di Ferrara e INFN, Via Saragat 1-44122, Ferrara, Italy; (21) Dipartimento di Chimica, Universita e INFN, Perugia; 06123, Italy; (22) Amherst Center for Fundamental Interactions, Physics Department, University of Massachusetts, Amherst; MA; 01003, United States; (23) Physics and Astronomy Department, University of California Los Angeles (UCLA), Los Angeles; CA; 90095, United States; (24) Institute of Physics and Excellence Cluster PRISMA, Johannes Gutenberg-Universität Mainz, Mainz; 55099, Germany^9

[关键词] Electron antineutrinos;Geo-neutrinos;Geosciences;Interdisciplinary fields;Liquid scintillator detectors;Low background;Radiogenic heat production;Solar neutrino