In recent years, a good deal of research work on solar physics has been devoted to finding evidence for the presence of neutrinos in the solar beam arriving on earth, because it was believed that a positive finding would constitute a direct proof of the theory of nuclear fusion in the sun as the source of its energy. Attempts have been made by astrophysicists in several countries in this direction. After decades of search, the first positive evidence was reported from the United States of America where Raymond Davies, Jr., of the Brookhaven National Laboratory who later became a research professor in the University of Pennsylvania, succeeded in capturing solar neutrinos in a tank deep underground in a South Dakota mine. He started his research work in 1961 by placing a large tank of perchloroethylene - commonly used as a drycleaning fluid - in a deep mine 2300 ft underground in the State of Ohio. With promising results from this work, he later installed a 100.000-gallon tank filled with perchloroethylene 4850 ft underground in the Homestake Gold Mine in Lead, South Dakota. After over 30 years of sustained work, he successfully observed as many as 2000 neutrino events which conclusively demonstrated the occurrence of nuclear fusion in the sun. Dr. Davies, Jr., was awarded a Nobel Prize in Physics in 2002 for his epoch-making discovery. He died in 2006 (The Washington Post, June 4, 2006).
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