Novel techniques for alpha/beta pulse shape discrimination in Borexino
Abstract
Borexino could efficiently distinguish between alpha and beta radiation in its liquid scintillator by the characteristic time profile of their scintillation pulse. This alpha/beta discrimination, first demonstrated at the tonne scale in the Counting Test Facility prototype, was used throughout the lifetime of the experiment between 2007 and 2021. With this method, alpha events are identified and subtracted from the beta-like solar neutrino events. This is particularly important in liquid scintillator as alpha scintillation is quenched many-fold. In Borexino, the prominent Po-210 decay peak was a background in the energy range of electrons scattered from Be-7 solar neutrinos. Optimal alpha-beta discrimination was achieved with a "multi-layer perceptron neural network", which its higher ability to leverage the timing information of the scintillation photons detected by the photomultiplier tubes. An event-by-event, high efficiency, stable, and uniform pulse shape discrimination was essential in characterising the spatial distribution of background in the detector. This benefited most Borexino measurements, including solar neutrinos in the \pp chain and the first direct observation of the CNO cycle in the Sun. This paper presents the key milestones in alpha/beta discrimination in Borexino as a term of comparison for current and future large liquid scintillator detectors
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Cite
@article{arxiv.2310.11826,
title = {Novel techniques for alpha/beta pulse shape discrimination in Borexino},
author = {D. Basilico and G. Bellini and J. Benziger and R. Biondi and B. Caccianiga and F. Calaprice and A. Caminata and A. Chepurnov and D. D'Angelo and A. Derbin and A. Di Giacintov and V. Di Marcello and X. F. Ding and A. Di Ludovico and L. Di Noto and I. Drachnev and D. Franco and C. Galbiati and C. Ghiano and M. Giammarchi and A. Goretti and M. Gromov and D. Guffanti and Aldo Ianni and Andrea Ianni and A. Jany 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 I. Machulin and J. Martyn and E. Meroni and L. Miramonti and M. Misiaszek and V. Muratova and R. Nugmanov and L. Oberauer and V. Orekhov and F. Ortica and M. Pallavicini and L. Pelicci and O. Penek and L. Pietrofaccia and N. Pilipenko and A. Pocar and G. Raikov and M. T. Ranalli and G. Ranucci and A. Razeto and A. Re and N. Rossi and S. Schoenert and D. Semenov and G. Settanta and M. Skorokhvatov and A. Singhal and O. Smirnov and A. Sotnikov and R. Tartaglia and G. Testera and E. Unzhakov and A. Vishneva and R. B. Vogelaar and F. von Feilitzsch and M. Wojcik and M. Wurm and S. Zavatarelli and K. Zuber and G. Zuzel},
journal= {arXiv preprint arXiv:2310.11826},
year = {2024}
}
Comments
13 pages, 14 figures