Measurement of neutrino flux from the primary proton--proton fusion process in the Sun with Borexino detector

TL;DR

This study reports the first real-time detection of neutrinos from the Sun's primary proton-proton fusion process using the Borexino detector, confirming solar models and constraining unknown energy sources.

Contribution

It provides the first spectrometric, real-time measurement of pp-neutrinos, enabling direct testing of solar energy production and stability.

Findings

First detection of pp-neutrinos in real-time

Limits on unknown solar energy sources set at 4%

Confirmation of solar fusion models

Abstract

Neutrino produced in a chain of nuclear reactions in the Sun starting from the fusion of two protons, for the first time has been detected in a real-time detector in spectrometric mode. The unique properties of the Borexino detector provided an oppurtunity to disentangle pp-neutrino spectrum from the background components. A comparison of the total neutrino flux from the Sun with Solar luminosity in photons provides a test of the stability of the Sun on the 10$^{5}$ years time scale, and sets a strong limit on the power production in the unknown energy sources in the Sun of no more than 4\% of the total energy production at 90\% C.L.