Eur. Phys. J. C (2020) 80: 1091
https://doi.org/10.1140/epjc/s10052-020-08534-2

Regular Article - Experimental Physics

Sensitivity to neutrinos from the solar CNO cycle in Borexino

¹ Physik-Department and Excellence Cluster Universe, Technische Universität München, 85748, Garching, Germany
² National Research Centre Kurchatov Institute, 123182, Moscow, Russia
³ Institut für Kernphysik, Forschungszentrum Jülich, 52425, Jülich, Germany
⁴ Dipartimento di Fisica, Università degli Studi and INFN, 20133, Milan, Italy
⁵ Chemical Engineering Department, Princeton University, 08544, Princeton, NJ, USA
⁶ INFN Laboratori Nazionali del Gran Sasso, 67010, Assergi, AQ, Italy
⁷ Physics Department, Princeton University, 08544, Princeton, NJ, USA
⁸ Dipartimento di Fisica, Università degli Studi and INFN, 16146, Genoa, Italy
⁹ Physics Department, Virginia Polytechnic Institute and State University, 24061, Blacksburg, VA, USA
¹⁰ Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, 119234, Moscow, Russia
¹¹ St. Petersburg Nuclear Physics Institute NRC Kurchatov Institute, 188350, Gatchina, Russia
¹² Joint Institute for Nuclear Research, 141980, Dubna, Russia
¹³ AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, 75205, Paris Cedex 13, France
¹⁴ Gran Sasso Science Institute, 67100, L’Aquila, Italy
¹⁵ III. Physikalisches Institut B, RWTH Aachen University, 52062, Aachen, Germany
¹⁶ Institute of Physics and Excellence Cluster PRISMA+, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
¹⁷ M. Smoluchowski Institute of Physics, Jagiellonian University, 30348, Kraków, Poland
¹⁸ Institute for Nuclear Research, 03028, Kyiv, Ukraine
¹⁹ Department of Physics, School of Engineering, Physical and Mathematical Sciences, Royal Holloway, University of London, Egham, UK
²⁰ National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Moscow, Russia
²¹ Department of Physics, Technische Universität Dresden, 01062, Dresden, Germany
²² Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi e INFN, 06123, Perugia, Italy
²³ Amherst Center for Fundamental Interactions and Physics Department, University of Massachusetts, 01003, Amherst, MA, USA
²⁴ Dipartimento di Scienze Fisiche e Chimiche, Università dell’Aquila, 67100, L’Aquila, Italy
²⁵ Department of Physics, University of California, 94720, Berkeley, CA, USA
²⁶ Departamento de Física Teórica, Universidad Autónoma de Madrid, Campus Universitario de Cantoblanco, 28049, Madrid, Spain
²⁷ INFN Laboratori Nazionali del Gran Sasso, 67010, Assergi, AQ, Italy
²⁸ Dipartimento di Fisica, Università degli Studi Federico II e INFN, 80126, Naples, Italy

^x xuefengd@princeton.edu
^bz gioacchino.ranucci@mi.infn.it

Received: 26 May 2020
Accepted: 12 October 2020
Published online: 26 November 2020

Abstract

Neutrinos emitted in the carbon, nitrogen, oxygen (CNO) fusion cycle in the Sun are a sub-dominant, yet crucial component of solar neutrinos whose flux has not been measured yet. The Borexino experiment at the Laboratori Nazionali del Gran Sasso (Italy) has a unique opportunity to detect them directly thanks to the detector’s radiopurity and the precise understanding of the detector backgrounds. We discuss the sensitivity of Borexino to CNO neutrinos, which is based on the strategies we adopted to constrain the rates of the two most relevant background sources, $\mathit{pep}$ neutrinos from the solar pp-chain and ${}^{210}$Bi beta decays originating in the intrinsic contamination of the liquid scintillator with ${}^{210}$Pb. Assuming the CNO flux predicted by the high-metallicity Standard Solar Model and an exposure of 1000 days $\times$ 71.3 t, Borexino has a median sensitivity to CNO neutrino higher than 3 $\sigma$. With the same hypothesis the expected experimental uncertainty on the CNO neutrino flux is 23%, provided the uncertainty on the independent estimate of the ${}^{210}\text{Bi}$ interaction rate is 1.5 $\text{cpd}/100\text{ton}$ . Finally, we evaluated the expected uncertainty of the C and N abundances and the expected discrimination significance between the high and low metallicity Standard Solar Models (HZ and LZ) with future more precise measurement of the CNO solar neutrino flux.