to different neutrino energy ranges. The Homestake experiment used chlorine and was most sensitive to solar neutrinos produced by the decay of the beryllium isotope 7Be. The Sudbury Neutrino Observatory is most sensitive to solar neutrinos produced by 8B. The detectors that use gallium are most sensitive to the solar neutrinos produced by the proton–proton chain reaction process, however they were not able to observe this contribution separately. The observation of the neutrinos from the basic reaction of this chain, proton–proton fusion in deuterium, was achieved for the first time by Borexino in 2014. In 2012 the same collaboration reported detecting low-energy neutrinos for the proton–electron–proton (pep reaction) that produces 1 in 400 deuterium nuclei in the Sun. The detector contained 100 metric tons of liquid and saw on average 3 events each day (due to C production) from this relatively uncommon thermonuclear reaction. In 2014, Borexino reported a successful direct detection of neutrinos from the pp-reaction at a rate of 144±33/day, consistent with the predicted rate of 131±2/day that was expected based on the standard solar model prediction that the pp-reaction generates 99% of the Sun's luminosity and their analysis of the detector's efficiency. And in 2020, Borexino reported the first detection of CNO cycle neutrinos from deep within the solar core. Note that Borexino measured neutrinos of several energies; in this manner they have demonstrated experimentally, for the first time, the pattern of solar neutrino oscillations predicted by the theory. Neutrinos can trigger nuclear reactions. By looking at ancient ores of various ages that have been exposed to solar neutrinos over geologic time, it may be possible to interrogate the luminosity of the Sun over time, which, according to the standard solar model, has changed over the eons as the (presently) inert byproduct helium has accumulated in its core. Key contributing astrophysicists Wolfgang Pauli was the first to suggest the idea of a particle such as the neutrino existing in our universe in 1930. He believed such a particle to be completely massless. This was the belief amongst the astrophysics community until the solar neutrino problem was solved. Frederick Reines, from the University of California at Irvine, and George A. Cowan were the first astrophysicists to detect neutrinos in 1956. They won a Nobel Prize in Physics for their work in 1995. Raymond Davis and John Bahcall are the pioneers of solar neutrino studies. While Bahcall never won