Detecting Solar Neutrino Flares and Flavors

Abstract

Intense solar flares originated in sun spots produce high energy particles (protons, $α$) well observable by satellites and ground-based detectors. The flare onset produces signals in different energy bands (radio, X, gamma and neutrons). The most powerful solar flares as the ones occurred on 23 February 1956, 29 September 1989 and the more recent on October 28th, and the 2nd, 4th, 13th of November 2003 released in sharp times the largest flare energies (${E}_{FL} \simeq {10}^{31}÷{10}^{32} erg). The high energy solar flare protons scatter within the solar corona and they must be source of a prompt neutrino burst through the production of charged pions. Later on, solar flare particles hitting the atmosphere may marginally increase the atmospheric neutrino flux. The prompt solar neutrino flare may be detected in the largest underground $ν$ detectors. Our estimate for the October - November 2003 solar flares gives a number of events above the unity. The electron/muon $ν$ signals and spectra may reflect the neutrino flavour mixing. A surprising tau appearance may occur for a hard {E}_nu_mu}} \to {E}_{ν_τ}\simeq> 4 GeV$) flare spectra.