Nobel Prize Treasure
By Joseph Skelly, PhD
During my tenure at Brookhaven National Lab (BNL) 1971-2008, in the Physics and Accelerator Departments, I was privileged to work with some of the brightest minds on the planet. I witnessed some fascinating stories of scientific discovery, and some unusual and little-known stories of human interest. This is one of the latter, about a chemist at BNL, Ray Davis.
The Science
The neutrino is one of the more obscure members of the zoo of elementary particles that physicist’s study, like the better-known neutron, proton, and electron. Its existence was predicted in 1930, when physicists saw that energy was missing when the neutron decayed into a proton and an electron. So there had to be something else with the missing energy – a small unnoticed neutral particle, the neutrino, was postulated. The annoying thing about the neutrino was that besides having no electric charge, it almost did not interact at all with anything else – it was almost unobservable, because of its peculiar particle properties; it was the proverbial black cat in a coal mine at midnight. The neutrino was finally detected in a 1956 experiment, awarded the Nobel prize in Physics in 1995. This experiment detected antineutrinos coming from a nuclear reactor. In 1965, neutrinos coming from the sun were observed in a 3-kilometer-deep underground detector in South Africa.
Ray Davis
In the late 1960’s a chemist, Ray Davis from BNL, put together an experiment that was able to measure accurately the total flux of neutrinos coming from the sun, in a detector buried deep underground at the old Homestake Gold Mine in Lead, South Dakota. Strangely, only a chemist could have done this physics experiment because it relied on chemical reactions induced by the neutrinos. Physicists by this time had a pretty good idea of how the nuclear reactions in the sun worked and knew what the flux of solar neutrinos ought to be. And Ray Davis’ experiment observed less than half of the flux expected! Something had to be wrong, either the experiment, or our ideas of how the sun worked! It took more than 30 years for this conundrum to be resolved, with additional experiments and a lot of work on the theories. Finally, it was proven that there are three kinds, or flavors, of neutrinos; the sun emits only one flavor, but on the way to the earth, the flavors are re-blended. By the time the solar neutrinos reach the earth, they are evenly divided among the three flavors, and Ray Davis’ experiment was only sensitive to one of the flavors.
Nobel Prize
The Nobel prize in Physics in 2002 was shared by Ray Davis and two physicists, for their developments in this field. By this time, Ray was 88 years old and suffering from Alzheimer’s Disease. Nevertheless, he received his prize in Stockholm and delivered his Nobel lecture. Sometime later, I had the good fortune to be lunching in the cafeteria at BNL when Ray and his wife came in for lunch. His table was surrounded by scientists eager to congratulate him. As Luck would have it I was among them. He had brought with him his Nobel award certificate and showed it to us all – an extraordinary thing, one of a kind, with special unique artwork and calligraphy. This is a memory I treasure. The 2002 Nobel Prize in Physics is one of seven Nobel Prizes that have been awarded to scientists for research done (partially or totally) at BNL.
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