Norman Ramsey

Norman Foster Ramsey (1970)

Norman Foster Ramsey (born August 27, 1915 in Washington, DC - † November 4, 2011 in Wayland , Middlesex County , Massachusetts ) was an American physicist . In 1989 he received the Nobel Prize in Physics for his work, which led to improved spectroscopic methods in atomic, molecular and nuclear physics and to precise time and frequency measurements. These methods are the basis of time measurement with atomic clocks .

life and work

Ramsey was born the son of an officer and a German-born former math lecturer (at the University of Kansas ). The family moved frequently because of the father's military transfers. a. to Paris. From 1931 he began to study engineering at Columbia University , but switched to mathematics, where he received an assistant position even before his graduation due to regularly won competitions. After graduation ( Bachelor ) in 1935 he attended Cambridge University in England, where he obtained a Bachelor's degree in physics, Maurice Goldhaber was his tutor.

Norman Foster Ramsey (right) with the Little Boy atomic bomb , 1945

Then he worked again at Columbia University in the group of Isidor Isaac Rabi , who had just invented the molecular beam magnetic resonance method. Together with Rabi and his colleagues Kellogg and Zacharias, he investigated nuclear moments and discovered the electrical quadrupole moment of the deuteron . After completing his doctorate with Rabi in 1940, he went to Washington, DC, as a Fellow of the Carnegie Institution to study neutron - proton scattering and the scattering of neutrons on helium nuclei .

During the Second World War, he initially worked in radar research at the MIT Radiation Lab (development of a 3 cm radar) and from 1943 on the Manhattan Project for the development of atomic bombs in Los Alamos .

After the Second World War he resumed his molecular beam experiments with Rabi as a professor at Columbia University and investigated the hyperfine structure in the spectrum of the hydrogen atom. With Rabi he was one of the initiators of the Brookhaven National Laboratory , whose first head of the physics department was Ramsey in 1946. In 1947 he became a professor at Harvard , where he set up a laboratory for molecular beam experiments. Here he developed the " Separated oscillatory field method " for magnetic resonance experiments and carried out numerous experiments on molecular and nuclear physics with his students and colleagues (nuclear moments, nuclear spins , electron distribution in molecules, spin-spin interaction, etc.). Together with his student Daniel Kleppner , he developed the hydrogen maser , with which he carried out precision investigations into hyperfine structure. With Robert Vessot and others, they also developed an atomic clock from it. In 1950, Ramsey was elected to the American Academy of Arts and Sciences .

Ramsey also led a group working on neutron beams a. At the Laue-Langevin Institute in Grenoble . a. the magnetic dipole moment of the neutron gave precise and upper limits for a possible electric dipole moment (if this exists, it would be an example of the violation of time-reversal invariance ). At Harvard he was also director of the "Harvard Cyclotron", a cyclotron accelerator with which he and his colleagues studied proton-proton scattering, and was involved in the construction of the 6 GeV electron accelerator in Cambridge, which he used in the 1960s Years u. a. studied electron-proton scattering.

In 1986 he retired from Harvard, but remained active as a physicist.

Ramsey also wrote theoretical papers, u. a. on the interaction of nuclei in molecules including chemical effects of NMR , early work on parity and time-reversal invariance and the concept of negative temperatures.

Norman Ramsey (left), Francis Perrin (center) and Robert R. Wilson (right), 1970

As Scientific Advisor to NATO Secretary General, he initiated the NATO Advanced Study Programs. As long-time President of the Universities Research Association, he was also involved in the development of the Fermilab .

Ramsey was married twice, first marriage from 1940 to 1983.

Awards

1950 member of the American Academy of Arts and Sciences
1952 member of the National Academy of Sciences
1958 member of the American Philosophical Society
1960 Ernest Orlando Lawrence Prize
1988 National Medal of Science
1989 Foreign member of the Académie des Sciences
1974 Davisson-Germer Prize
1985 Rabi Prize .
1989 Nobel Prize in Physics

He was multiple honorary doctor , u. a. the University of Chicago , Rockefeller University , Oxford .

Fonts

with Emilio Segrè : Experimental Nuclear Physics . Wiley, 1953
Nuclear Moments . John Wiley, 1953
Molecular Beams . Oxford University Press, 1956, 1985
with Daniel Kleppner : Quick Calculus . Wiley, 1965, 1985
with Isidor Isaac Rabi , J. Kellogg and J. Zacharias: Magnetic Moments of Proton and Deuteron. Radiofrequency Spectrum of H2 in Magnetic fields. In: Physical Review . Volume 56, 1939, p. 728.
with Rabi, Kellogg and Zacharias: Electrical Quadrupole Moment of the Deuteron. Radiofrequency Spectra of HD and D2 Molecules in a Magnetric Field . In: Physical Review . Volume 57, 1940, p. 677
Molecular Beam Resonance Method with Separated Oscillating Fields . In: Physical Review . Volume 78, 1950, p. 695
Thermodynamics and Statistical Mechanics at Negative Absolute Temperatures . In: Physical Review . Volume 103, 1956, p. 20.
with J. Smith and Edward Purcell : Experimental Limit to the Electric Dipole Moment of the Neutron . In: Physical Review . Volume 108, 1957, p. 120
Time Reversal, Charge Conjugation, Magnetic Pole Conjugation and Parity . In: Physical Review . Volume 109, 1958, p. 225.
with Kleppner and H. Goldenberg: Atomic Hydrogen Maser . In: Physical Review Letters . Volume 8, 1960, p. 361
with Kleppner and Goldenberg: Theory of the Hydrogen Maser . In: Physical Review . Volume 126, 1962, p. 603.
with S. Crampton and Kleppner: Hyperfine Structure of Ground State of Atomic Hydrogen . In: Physical Review Letters . Volume 11, 1963, p. 338.
with Kleppner, H. Berg, Crampton, Vessot, H. Peters and J. Vanier: Hydrogen Maser Principles and Techniques . In: Physical Review A . Volume 138, 1965, p. 972.

literature

David Wineland : Norman Ramsey (1915-2011). Physicist behind precision spectroscopy and atomic clocks. In: Nature , Volume 480, No. 7376, 2011, p. 182, doi: 10.1038 / 480182a

Web links

Commons : Norman Foster Ramsey - Collection of images, videos and audio files

Information from the Nobel Foundation on the 1989 award ceremony for Norman Foster Ramsey (English)
Norman Ramsey. In: Physics History Network. American Institute of Physics

Individual evidence

↑ Norman Ramsey Dies at 96; Work Led to the Atomic Clock
↑ Here, particles are exposed to two time-separated radiation pulses in order to increase the resolution with which the structure of the energy levels can be measured. This method is widely used today in high-precision and quantum physics and is e.g. B. essential component in many atomic clocks.

personal data
SURNAME	Ramsey, Norman
ALTERNATIVE NAMES	Ramsey, Norman Foster (full name)
BRIEF DESCRIPTION	American physicist and Nobel Prize winner
DATE OF BIRTH	August 27, 1915
PLACE OF BIRTH	Washington, DC
DATE OF DEATH	November 4, 2011
Place of death	Wayland , Middlesex County , Massachusetts

[1] Norman Ramsey Dies at 96; Work Led to the Atomic Clock

[2] Here, particles are exposed to two time-separated radiation pulses in order to increase the resolution with which the structure of the energy levels can be measured. This method is widely used today in high-precision and quantum physics and is e.g. B. essential component in many atomic clocks.