@article{3c28eb7ef65845bfba96e09eac8410f0,
title = "Correlated and integrated directionality for sub-MeV solar neutrinos in Borexino",
abstract = "Liquid scintillator detectors play a central role in the detection of neutrinos from various sources. In particular, it is the only technique used so far for the precision spectroscopy of sub-MeV solar neutrinos, as demonstrated by the Borexino experiment at the Gran Sasso National Laboratory in Italy. The benefit of a high light yield, and thus a low energy threshold and a good energy resolution, comes at the cost of the directional information featured by water Cherenkov detectors, measuring B8 solar neutrinos above a few MeV. In this paper we provide the first directionality measurement of sub-MeV solar neutrinos which exploits the correlation between the first few detected photons in each event and the known position of the Sun for each event. This is also the first signature of directionality in neutrinos elastically scattering off electrons in a liquid scintillator target. This measurement exploits the subdominant, fast Cherenkov light emission that precedes the dominant yet slower scintillation light signal. Through this measurement, we have also been able to extract the rate of Be7 solar neutrinos in Borexino. The demonstration of directional sensitivity in a traditional liquid scintillator target paves the way for the possible exploitation of the Cherenkov light signal in future kton-scale experiments using liquid scintillator targets. Directionality is important for background suppression as well as the disentanglement of signals from various sources.",
author = "{(Borexino Collaboration)} and M. Agostini and K. Altenm{\"u}ller and S. Appel and V. Atroshchenko and Z. Bagdasarian and D. Basilico and G. Bellini and J. Benziger and R. Biondi and D. Bravo and B. Caccianiga and F. Calaprice and A. Caminata and P. Cavalcante and A. Chepurnov and D. D'Angelo and S. Davini and A. Derbin and {Di Giacinto}, A. and {Di Marcello}, V. and Ding, {X. F.} and {Di Ludovico}, A. and {Di Noto}, L. and I. Drachnev and A. Formozov and D. Franco and C. Galbiati and C. Ghiano and M. Giammarchi and A. Goretti and G{\"o}ttel, {A. S.} and M. Gromov and D. Guffanti and Aldo Ianni and Andrea Ianni and A. Jany and D. Jeschke and V. Kobychev and G. Korga and S. Kumaran and M. Laubenstein and E. Litvinovich and P. Lombardi and I. Lomskaya and L. Ludhova and G. Lukyanchenko and L. Lukyanchenko and I. MacHulin and J. Martyn and E. Meroni",
note = "Funding Information: We acknowledge the generous hospitality and support of the Laboratori Nazionali del Gran Sasso (Italy). The Borexino program is made possible by funding from Istituto Nazionale di Fisica Nucleare (INFN) (Italy), National Science Foundation (NSF) (USA), Deutsche Forschungsgemeinschaft (DFG), Cluster of Excellence PRISMA+ (Project ID 390831469), and recruitment initiative of Helmholtz-Gemeinschaft (HGF) (Germany), Russian Foundation for Basic Research (RFBR) (Grants No. 19-02-00097A) and Russian Science Foundation (RSF) (Grant No. 21-12-00063) (Russia), and Narodowe Centrum Nauki (NCN) (Grant No. UMO 2017/26/M/ST2/00915) (Poland). We gratefully acknowledge the computing services of Bologna INFN-Centro Nazionale Analisi Fotogrammi (CNAF) data center and U-Lite Computing Center and Network Service at LNGS (Italy). Publisher Copyright: {\textcopyright} 2022 authors. Published by the American Physical Society. Published by the American Physical Society.",
year = "2022",
month = mar,
day = "1",
doi = "10.1103/PhysRevD.105.052002",
language = "English (US)",
volume = "105",
journal = "Physical Review D",
issn = "2470-0010",
publisher = "American Physical Society",
number = "5",
}