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  • Identification of the cosmo...
    Agostini, M.; Altenmüller, K.; Appel, S.; Atroshchenko, V.; Bagdasarian, Z.; Basilico, D.; Bellini, G.; Benziger, J.; Biondi, R.; Bravo, D.; Caccianiga, B.; Calaprice, F.; Caminata, A.; Cavalcante, P.; Chepurnov, A.; D’Angelo, D.; Davini, S.; Derbin, A.; Di ZGiacintio, A.; Di Marcello, V.; Ding, X. F.; Di Ludovico, A.; Di Noto, L.; Drachnev, I.; Formozov, A.; Franco, D.; Galbiati, C.; Ghiano, C.; Giammarchi, M.; Goretti, A.; Göttel, A. S.; Gromov, M.; Guffanti, D.; Ianni, Aldo; Ianni, Andrea; Jany, A.; Jeschke, D.; Kobychev, V.; Korga, G.; Kumaran, S.; Laubenstein, M.; Litvinovich, E.; Lombardi, P.; Lomskaya, I.; Ludhova, L.; Lukyanchenko, G.; Lukyanchenko, L.; Machulin, I.; Martyn, J.; Meroni, E.; Meyer, M.; Miramonti, L.; Misiaszek, M.; Muratova, V.; Neumair, B.; Nieslony, M.; Nugmanov, R.; Oberauer, L.; Orekhov, V.; Ortica, F.; Pallavicini, M.; Papp, L.; Pelicci, L.; Penek, Ö.; Pietrofaccia, L.; Pilipenko, N.; Pocar, A.; Porcelli, A.; Raikov, G.; Ranalli, M. T.; Ranucci, G.; Razeto, A.; Re, A.; Redchuk, M.; Romani, A.; Rossi, N.; Schönert, S.; Semenov, D.; Settanta, G.; Skorokhvatov, M.; Singhal, A.; Smirnov, O.; Sotnikov, A.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Thurn, J.; Unzhakov, E.; Vishneva, A.; Vogelaar, R. B.; von Feilitzsch, F.; Wojcik, M.; Wurm, M.; Zavatarelli, S.; Zuber, K.; Zuzel, G.

    The European physical journal. C, Particles and fields, 12/2021, Letnik: 81, Številka: 12
    Journal Article

    Cosmogenic radio-nuclei are an important source of background for low-energy neutrino experiments. In Borexino, cosmogenic 11 C decays outnumber solar pep and CNO neutrino events by about ten to one. In order to extract the flux of these two neutrino species, a highly efficient identification of this background is mandatory. We present here the details of the most consolidated strategy, used throughout Borexino solar neutrino measurements. It hinges upon finding the space-time correlations between 11 C decays, the preceding parent muons and the accompanying neutrons. This article describes the working principles and evaluates the performance of this Three-Fold Coincidence (TFC) technique in its two current implementations: a hard-cut and a likelihood-based approach. Both show stable performances throughout Borexino Phases II (2012–2016) and III (2016–2020) data sets, with a 11 C tagging efficiency of ∼ 90  % and ∼  63–66 % of the exposure surviving the tagging. We present also a novel technique that targets specifically 11 C produced in high-multiplicity during major spallation events. Such 11 C appear as a burst of events, whose space-time correlation can be exploited. Burst identification can be combined with the TFC to obtain about the same tagging efficiency of ∼ 90 % but with a higher fraction of the exposure surviving, in the range of ∼  66–68 %.