Final results of Borexino Phase-I on low-energy solar neutrino spectroscopy
Top Cited Papers
- 25 June 2014
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review D
- Vol. 89 (11), 112007
- https://doi.org/10.1103/physrevd.89.112007
Abstract
Borexino has been running since May 2007 at the Laboratori Nazionali del Gran Sasso laboratory in Italy with the primary goal of detecting solar neutrinos. The detector, a large, unsegmented liquid scintillator calorimeter characterized by unprecedented low levels of intrinsic radioactivity, is optimized for the study of the lower energy part of the spectrum. During Phase-I (2007–2010), Borexino first detected and then precisely measured the flux of the solar neutrinos, ruled out any significant day-night asymmetry of their interaction rate, made the first direct observation of the pep neutrinos, and set the tightest upper limit on the flux of solar neutrinos produced in the CNO cycle (carbon, nitrogen, oxigen) where carbon, nitrogen, and oxygen serve as catalysts in the fusion process. In this paper we discuss the signal signature and provide a comprehensive description of the backgrounds, quantify their event rates, describe the methods for their identification, selection, or subtraction, and describe data analysis. Key features are an extensive in situ calibration program using radioactive sources, the detailed modeling of the detector response, the ability to define an innermost fiducial volume with extremely low background via software cuts, and the excellent pulse-shape discrimination capability of the scintillator that allows particle identification. We report a measurement of the annual modulation of the neutrino interaction rate. The period, the amplitude, and the phase of the observed modulation are consistent with the solar origin of these events, and the absence of their annual modulation is rejected with higher than 99% C.L. The physics implications of Phase-I results in the context of the neutrino oscillation physics and solar models are presented.
Keywords
Other Versions
Funding Information
- National Science Foundation
- Deutsche Forschungsgemeinschaft
This publication has 96 references indexed in Scilit:
- Cosmogenic Backgrounds in Borexino at 3800 m water-equivalent depthJournal of Cosmology and Astroparticle Physics, 2013
- SOLAR MODELS WITH ACCRETION. I. APPLICATION TO THE SOLAR ABUNDANCE PROBLEMThe Astrophysical Journal, 2011
- Search for solar axions emitted in the M1-transition of 7Li* with Borexino CTFThe European Physical Journal C, 2008
- Solar neutrinos as probes of neutrino–matter interactionsPhysics Letters B, 2004
- Solar models and solar neutrino oscillationsNew Journal of Physics, 2004
- Homestake result, sterile neutrinos, and low energy solar neutrino experimentsPhysical Review D, 2004
- Study of neutrino electromagnetic properties with the prototype of the Borexino detectorPhysics Letters B, 2003
- Does the Sun appear brighter at night in neutrinos?Physical Review C, 1997
- Comprehensive analysis of solar, atmospheric, accelerator, and reactor neutrino experiments in a hierarchical three-generation schemePhysical Review D, 1994
- Preliminary reference Earth modelPhysics of the Earth and Planetary Interiors, 1981