Ramsey, Norman F (1915– )

US physicist who invented a method of storing atoms and observing them for long periods of time, and applied this in the hydrogen maser and atomic clock. He was awarded the Nobel Prize for Physics in 1989 for his measurement techniques leading to the discovery of the caesium atomic clock which has been the basis for the definition of the unit of time (the second) since 1967. He shared the award with Hans Dehmelt and Wolfgang Paul.

Ramsey's invention is called the method of separated oscillatory fields. In this method, a beam of atoms passes through an oscillating (rapidly varying) magnetic field at one end of a storage box. Inside the box, the atoms bounce around for a period of time before emerging through a second oscillating field at the opposite end of the box.

Ramsey was born in Washington, DC, USA, and educated at Columbia University, New York, and Cambridge University, England. After receiving from Cambridge his second bachelor's degree, he returned to Columbia to study for his doctorate. During World War II he worked on radar and at Los Alamos, New Mexico, on the atomic bomb project. At the end of the war he returned to Columbia as professor. In 1946 he became the first head of the physics department at the newly established Brookhaven National Laboratory, Long Island, New York. In 1947 he moved to Harvard where he taught for 40 years, retiring in 1986.