The Nobel Prize in Physics 2002
Raymond Davis Jr., Masatoshi Koshiba, Riccardo Giacconi
Raymond Davis Jr.
Born: 14 October 1914, Washington, DC, USA
Died: 31 May 2006, Blue Point, NY, USA
Affiliation at the time of the award: University of Pennsylvania, Philadelphia, PA, USA
Prize motivation: "for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos"
Field: neutrino astrophysics
Prize share: 1/4
In certain nuclear reactions, e.g. the fusion reaction when four protons are combined to form a helium nucleus, elusive particles called neutrinos are created. Raymond Davies wanted to detect neutrinos from space in order to confirm that fusion reactions were the source of the energy from the sun. Starting in the 1960s, he placed a large tank containing a liquid rich in chlorine deep down in a gold mine. In rare cases a neutrino could interact with a chlorine atom creating a radioactive argon atom. By counting the argon atoms, neutrinos from space could be detected.