D. Jeschke

Borexino's search for low-energy neutrino and antineutrino signals correlated with gamma-ray bursts

Abstract A search for neutrino and antineutrino events correlated with 2350 gamma-ray bursts (GRBs) is performed with Borexino data collected between December 2007 and November 2015. No statistically significant excess over background is observed. We look for electron antineutrinos ( ν ¯ e ) that inverse beta decay on protons with energies from 1.8xa0xa0MeV to 15xa0xa0MeV and set the best limit on the neutrino fluence from GRBs below 8xa0xa0MeV. The signals from neutrinos and antineutrinos from GRBs that scatter on electrons are also searched for, a detection channel made possible by the particularly radio-pure scintillator of Borexino. We obtain currently the best limits on the neutrino fluence of all flavors and species below 7xa0xa0MeV. Finally, time correlations between GRBs and bursts of events are investigated. Our analysis combines two semi-independent data acquisition systems for the first time: the primary Borexino readout optimized for solar neutrino physics up to a few MeV, and a fast waveform digitizer system tuned for events above 1xa0MeV.

Recent results from Borexino

We review the solar neutrinos results of Borexino and the limit on the charge conservation obtained in the context of the analysis of the low energy region of the energy spectrum.

Test of the electron stability with the Borexino detector

Despite the fact that the electric charge conservation law is confirmed by many experiments, search for its possible violation remains a way of searching for physics beyond the Standard Model. Experimental searches for the electric charge non-conservation mainly consider electron decays into neutral particles. The Borexino experiment is an excellent tool for the electron decay search due to the highest radiopurity among all the existing experiments, large detector mass, and good sensitivity at low energies. The process considered in this study is a decay into a photon and a neutrino, for which a new lower limit on the electron lifetime is obtained. This is the best electron lifetime limit up to date, exceeding the previous one obtained at the Borexino prototype at two orders of magnitude.

Measurement of solar neutrino fluxes with Borexino

Solar neutrinos have been of extraordinary importance for the discovery of neutrino oscillations and allow to study directly the Suns innermost core. The Borexino experiment, located in the Gran Sasso National Laboratory, is an ultra-pure liquid scintillator detector conceived for the real time spectroscopy of low energy solar neutrinos. We review Borexinos results and we discuss its upcoming future, since the precision era of solar neutrino measurements has just started.