Nobel Laureate Frederick Reines (1918-1998)

Distinguished Professor Emeritus, Elementary Particle Physics

The award of the 1995 Nobel Prize in Physics to the late Frederick Reines provided the ultimate recognition of an extraordinary discovery and an exceptional scientific career in pursuit of fundamental knowledge. Perhaps no scientist in history has been associated so intimately with the discovery of an elementary particle and the subsequent thorough investigation of its properties as has Frederick Reines.

Professor Reines earned his M.E. and M.S. degrees from Stevens Institute of Technology and his Ph.D. from New York University in 1944. He was a member and then Group Leader of the theoretical division of the Los Alamos Scientific Laboratory from 1944 to 1959. He was Professor and Chairman of the Physics Department at Case Institute of Technology from 1959 to 1966 and then went on to serve as Professor and founding Dean of Physical Sciences at UCI.

He is best known for his work, with Clyde Cowan in the mid-1950s, on the first detection of the neutrino. Reines then devoted the major part of his outstandingly productive career to the understanding of the neutrino's properties and interactions. This imposing volume of work has vastly enriched our knowledge of the properties of the neutrino and has also provided important information on its effect on astrophysical processes.

Reines' studies produced a host of fundamental findings and a number of "firsts." These include the detection of neutrinos produced in the atmosphere, the observation of the scattering of electron antineutrinos with electrons, and the detection of both neutral and charged current interactions of electron antineutrinos with deuterons. A dramatic achievement was the co-discovery of neutrinos emitted from Supernova SN1987A by the IMB (Irvine-Michigan-Brookhaven) Collaboration, which demonstrated conclusively the theoretically postulated role of the neutrino in stellar collapse. These findings continue to have important consequences for exploring and revealing aspects of the theory of electro-weak interactions.

In addition to these neutrino studies, Reines and his co-workers have pursued, for almost four decades, a related program of experiments to test fundamental conservation laws of nature. These experiments include tests of conservation of lepton number (which would be violated in the decay of electrons) and baryon number (which would be manifested in the decay of the proton).

A series of increasingly sensitive tests and detection techniques were devised to investigate the validity of these laws. This work, deriving directly from Reines' vision and foresight, demonstrated the feasibility and led to the development of large-scale detectors. Indeed, starting with his earliest studies of neutrinos and conservation laws, Reines led the development and pioneered the use of many new techniques, including the large-scale use of liquid scintillator and water Cerenkov detectors. The IMB experiment (of which Reines was co-spokesman) used an 8,000-ton water Cerenkov detector in a salt mine near Cleveland, Ohio, to set the best limits on the lifetime of the proton, thus significantly constraining particle theories.

The IMB detector was also used to study neutrino physics, primarily by studying neutrinos produced by interactions of cosmic rays in the atmosphere. Its impressive size and neutrino detection capability allowed the historic detection of a neutrino burst from the supernova SN1987A and led to the birth of the field of neutrino astronomy.

Nothing could be more fitting than that the experimental effort which culminated in the observation of neutrinos from SN1987A was led by Fred Reines. And there could be no more fitting tribute than the 1995 Nobel Prize to recognize the extraordinary association of Fred Reines and the neutrino.