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Neutrinos produced in the Sun have different energies. Different types of detectors are sensitive to different energy ranges.
Image courtesy of John Bahcall, Institute of Advanced Studies

The Solar Neutrino Problem

Theories about fusion inside the solar core predict the number of neutrinos that should reach Earth. Experiments on Earth have been set up to detect solar neutrinos in order to test these models. Current measurements show less neutrinos than the number predicted.

The first solar neutrino experiment was performed at the Homestake mine in South Dakota. A 600-ton chlorine fluid detector was used. It found a neutrino count about one third of that predicted.

The experiment at Kamioka, Japan, found about half of the predicted neutrinos. Recent experiments in Russia (SAGE) and Italy (GALLEX) use Gallium to detect neutrinos and have found neutrino fluxes up to 70% of the predicted flux.

Scientists are still trying to find out why their actual counts don't match up with the number of neutrinos that are predicted to come from the Sun.

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