In 2001, the result of experiments counting previously undetected, but theoretically predicted, solar neutrinos was announced by a collaboration of Canadian, American and British scientists led by Arthur McDonald. They detected all three types of solar neutrinos (electron, muon and tau), using the SNO (Solar Neutrino Observatory) consisting of 9,456 photomultiplier tubes lining a stainless steel tank containing 1,000 tons of heavy water (D2O) 6800-ft deep in a nickel mine at Sudbury, Ontario, Canada. The combined results agreed with the total flux calculated using the standard computer model of the Sun, thus finally confirming the long-standing theory accounting for the various nuclear reactions taking place within the Sun.«[Image: external view of the SNO's photomultiplier array during detector construction.]