Recent Borexino results and prospects for the near future

D D’angelo ,L Di Noto,S Weinz,B Lehnert,F Gabriele,L Perasso,A Pocar,E Meroni,M Obolensky,Y Suvorov,N Rossi,O Zaimidoroga,F Von Feilitzsch,A Caminata,R Roncin,A Sotnikov,J Thurn,B Caccianiga,D Bravo,S Appel,S Schönert,Z Yokley,Aldo Ianni,R Tartaglia,K Fomenko,G Bellini,G Zuzel,D Franco,B Neumair,M Goeger-Neff,A Vishneva,A Razeto,Andrea Ianni,G Lukyanchenko,L Papp,S Manecki,C Ghiano,W Maneschg,P Cavalcante,O Smirnov,S Davini,M Gromov,K Altenmüller,E Litvinovich,G Bonfini,S Marcocci,G Testera,G Korga,D Kryn,M Toropova,M Misiaszek,D Bick,J Winter,C Galbiati,M Wurm,E Hungerford,F Lombardi,K Jȩdrzejczak ,H Simgen,A Re,H Wang,D Semenov,S Sukhotin,V Muratova,F Ortica,M Giammarchi,J Benziger,G Ranucci,C Hagner,M Meyer,F Calaprice,I Machulin,M Skorokhvatov,I Drachnev,P Mosteiro,P Lombardi,M Wójcik ,M Laubenstein,A Goretti,A Etenko,L Ludhová ,V Kobychev,E Unzhakov,R B Vogelaar ,Κ Zuber ,M Montuschi,A Romani,S Zavatarelli,L Oberauer,M Agostini,A Chepurnov,M Pallavicini,D Korablëv ,L Miramonti,M Kaiser,A Derbin

doi:10.1051/epjconf/201612602008

Abstract

The Borexino experiment located in the Gran Sasso National Laboratory, is an organic liquid scintillator detector conceived for the real time spectroscopy of low energy solar neutrinos. The phase-I of the data taking campaign (2007 – 2010) has allowed the first independent measurements of 7 Be and pep solar neutrino fluxes as well as the first measurement of anti-neutrinos from the Earth. After a purification of the scintillator, Borexino is now in phase-II since 2011. Thanks to the unprecedented background levels, we have performed the first flux measurement of neutrinos from the fundamental pp reaction which powers the Sun. We review this breakthrough result and other recent results, including the latest review of our terrestrial neutrino analysis. We also discuss the upcoming measurements on middle energy solar neutrino spectral components (pep, CNO) and the new project SOX devoted to the study of sterile neutrinos via the use of a neutrino source placed in close proximity of the detector’s active material.

Highlights

The Sun is an intense source of neutrinos, produced in nuclear reactions of the p-p chain and of the CNO cycle [1]
The Borexino experiment located in the Gran Sasso National Laboratory, is an organic liquid scintillator detector conceived for the real time spectroscopy of low energy solar neutrinos
We discuss the upcoming measurements on middle energy solar neutrino spectral components and the new project Short distance Oscillation with boreXino (SOX) devoted to the study of sterile neutrinos via the use of a neutrino source placed in close proximity of the detector’s active material

Summary

Why solar neutrinos with Borexino

The Sun is an intense source of neutrinos, produced in nuclear reactions of the p-p chain and of the CNO cycle [1]. Measurements of the individual neutrino fluxes is of paramount importance for Figure 1. The solar neutrino spectrum can be seen in figure 1. Up to a few years ago, spectroscopical measurements were performed by water Cherenkov detectors above ∼5 Mev and concerned only 8B neutrinos for less 1% of the total flux. The bulk of neutrinos at low energies were detected only with radiochemical experiments, incapable of resolving the individual components. The MSW mechanism with Large Mixing Angle (LMA) foresees the survival probability for electron neutrinos on Earth after oscillation is taken into account, as shown in figure 2. Borexino was designed to perform spectroscopy of the low energy part of the solar neutrino spectrum, in particular the flux of the 7Be monochromatic line at 862 keV. Borexino has largely exceeded the expected performance and broadened the physics program past the original goal

The Borexino Project

Phase-I results

Geo-neutrinos

Findings

Conclusions and outlook