The phrase "neutrino flux" refers to the flow or quantity of neutrinos passing through a given area. It measures how many neutrinos are observed or detected in a specific region or detector. Full definition
Douglas Morrison of CERN, the European laboratory for particle physics, says the latest models of the way in which the Sun works predict solar neutrino fluxes which are almost consistent with the latest observations. (newscientist.com)
He decided to go public only after a paper in the Astrophysical Journal last December claimed a correlation between the magnetic field emerging from the surface of the Sun and the Homestake neutrino flux. (newscientist.com)
[14] Several neutrino observatories were built in the 1980s to measure the solar neutrino flux as accurately as possible, including the Sudbury Neutrino Observatory and Kamiokande. (newworldencyclopedia.org)