First real–time detection of solar pp neutrinos by Borexino

¹ Università di Genova, Dipartimento di Fisica, via Dodecaneso 33, 16146 Genova, Italy
² INFN Sezione di Genova, via Dodecaneso 33, 16146 Genova, Italy
³ Dipartimento di Fisica, Università degli Studi and INFN, Milano 20133, Italy
⁴ Chemical Engineering Department, Princeton University, Princeton, NJ 08544, USA
⁵ Institut für Experimentalphysik, Universität Hamburg, Germany
⁶ INFN Laboratori Nazionali del Gran Sasso, Assergi 67010, Italy
⁷ Physics Department, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
⁸ Physics Department, Princeton University, Princeton, NJ 08544, USA
⁹ Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow 119234, Russia
¹⁰ Department of Physics, University of Houston, Houston, TX 77204, USA
¹¹ St. Petersburg Nuclear Physics Institute, Gatchina 188350, Russia
¹² NRC Kurchatov Institute, Moscow 123182, Russia
¹³ Joint Institute for Nuclear Research, Dubna 141980, Russia
¹⁴ APC, Univ. Paris Diderot, CNRS/IN2P3, CEA/Irfu, Obs. de Paris, Sorbonne Paris Cité, France
¹⁵ Physik Department Technische Universität München, Garching 85747, Germany
¹⁶ National Nuclear Research University “MEPhI”, 31 Kashirskoe shosse, Moscow, Russia
¹⁷ Technische Universität Dresden, Institut für Kern und Teilchenphysik, Zellescher Weg 19, 01068 Dresden, Germany
¹⁸ M. Smoluchowski Institute of Physics, Jagiellonian University, Crakow 30059, Poland
¹⁹ Dipartimento di Chimica, Biologia e Biotecnologie, Università e INFN, Perugia 06123, Italy
²⁰ Max-Plank-Institut für Kernphysik, 69117 Heidelberg, Germany
²¹ Physics Department, University of Massachusetts, Amherst, MA 01003, USA
²² Physics ans Astronomy Department, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
²³ Institut für Physik, Johannes Gutenberg Universität Mainz, Germany
²⁴ Gran Sasso Science Institute (INFN), 67100 L'Aquila, Italy
²⁵ Kiev Institute for Nuclear Research, Kiev 06380, Ukraine

^a e-mail: marco.pallavicini@ge.infn.it

Published online: 6 July 2016

Abstract

Solar neutrinos have been pivotal to the discovery of neutrino flavour oscillations and are a unique tool to probe the reactions that keep the Sun shine. Although most of solar neutrino components have been directly measured, the neutrinos emitted by the keystone pp reaction, in which two protons fuse to make a deuteron, have so far eluded direct detection. The Borexino experiment, an ultra–pure liquid scintillator detector running at the Laboratori Nazionali del Gran Sasso in Italy, has now filled the gap, providing the first direct real time measurement of pp neutrinos and of the solar neutrino luminosity.