Raymond Davis Junior

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Raymond Davis Jr.

Raymond Davis Jr. (born October 14, 1914 in Washington, DC , † May 31, 2006 in Blue Point , New York ) was an American chemist and physicist who was awarded the Nobel Prize in Physics in 2002 for “pioneering work in astrophysics , especially for the detection of cosmic neutrinos ”.

Life

Raymond Davis was born the son of a photographer and his wife Ida Rogers Younger on October 14, 1914 in Washington DC. Under the influence of his father, who worked at the National Institute of Standards and Technology and later became head of the photographic technology department even though he hadn't finished high school, he began developing his own experiments and equipment at an early age.

After attending public schools in Washington, he graduated from the University of Maryland with a degree in chemistry in 1938. After a year at Dow Chemical in Midland , Michigan , he went back to the University in Maryland, he received his doctorate in physical chemistry from Yale University in 1942 and joined the army as a reserve officer. He spent the following years mainly at the Dugway Proving Ground in Utah observing tests with chemical weapons. After his discharge from the Army in 1945, he worked at Monsanto Chemical in Miamisburg, Ohio, on radiochemical methods of interest to the Atomic Energy Commission . In the spring of 1948 he went to the Brookhaven National Laboratory (BNL), which had been newly established for the development of civil applications of atomic energy. There he also met his wife Anna Torrey, who was employed in the biology department of the BNL. They married in late 1948. They have five children, Andrew, Martha Kumler, Nancy Klemm, Roger and Alan. He retired from the BNL in 1984 and went to the Department of Physics and Astronomy at the University of Pennsylvania in Philadelphia as a professor .

plant

Davis was not assigned a fixed task at the BNL, but could choose an area of ​​his choice - he decided on neutrino physics. At that time, neutrinos only existed as a theoretical postulate, there was no experimental work on them yet - it was therefore an ideal field of activity to contribute one's experience in radiochemistry.

His first experiment was the implementation of an idea by Bruno Pontecorvo from 1946 for the detection of neutrinos with the reaction 37 Cl + ν → 37 Ar + e that arise in a nuclear reactor . To this end, he built a 1000- gallon tank of carbon tetrachloride on the BNL's research reactor , and in 1955 a larger one near a reactor in the Savannah River Site . However, these experiments were negative. Later it turned out that the postulate of the identity of neutrinos and antineutrinos, favored at the time, was wrong - therefore no detection could be made, since antineutrinos are generated in the reactor, while the detection reaction to neutrinos is sensitive. It is noteworthy, however, that Davis achieved a 20-fold higher sensitivity for the neutrino flux than was necessary in 1956 for the experimental detection of reactor neutrinos by Frederick Reines , who received the Nobel Prize in Physics in 1995, and Clyde L. Cowan .

Following the Savannah experiments, he turned to the problem of solar neutrinos, a topic that would occupy him throughout his life. To do this, he built a pilot plant in the Barberton Limestone Mine near Akron , Ohio. In the 1960s, he built a 100,000 gallon tank of perchlorethylene at the Homestake gold mine in Lead , South Dakota, approximately 1,400 meters below ground . Although the first measurements were inconclusive, he refined the measurement techniques to such an extent that he was able to detect solar neutrinos for the first time around 1970. However, the measured flow was only about a third of the flow postulated by John N. Bahcall - the solar neutrino problem was to occupy theorists and experimenters for the following years and was only solved by the discovery of the neutrino oscillations .

Appreciation

Davis was a lone fighter throughout his life, who laid the foundations of modern neutrino physics through his work. He achieved this less through his results than through his uncompromising struggle to measure the “immeasurable”. He convinced the professional world with the demonstration of a reliable measurability of reaction rates with few events per month. It was only through his measurements that other researchers gained confidence in the feasibility and designed experiments such as the SNO , GALLEX or Super-Kamiokande . This opened the door to “new” physics beyond the accepted standard model .

For his achievements, he and Masatoshi Koshiba were awarded half of the Nobel Prize in Physics in 2002, the other half went to Riccardo Giacconi .

Davis was 88 years old at the time of the award and was the oldest person to ever receive a Nobel Prize until 2018.

Awards

Web links

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personal data
SURNAME Davis, Raymond Jr.
ALTERNATIVE NAMES Davis, Raymond Jr.
BRIEF DESCRIPTION American chemist and Nobel Prize winner
DATE OF BIRTH October 14, 1914
PLACE OF BIRTH Washington, DC
DATE OF DEATH May 31, 2006
Place of death Blue Point , New York