Erwin Hahn (physicist)

from Wikipedia, the free encyclopedia

Erwin Louis Hahn (born June 9, 1921 in Sharon , Pennsylvania , † September 20, 2016 ) was an American solid-state physicist.

Life

Hahn studied at the Juniata College of Purdue University (bachelor's degree in chemistry) and - after military service in World War II in the United States Navy , where he taught radar and sonar technology - at the University of Illinois as assistant to betatron developer Donald William Kerst . Since he did not like the, in his opinion, purely electrical engineering group work on the betatron, he switched to nuclear magnetic resonance (NMR), which had just been discovered by Edward Mills Purcell ( Harvard University ) and Felix Bloch ( Stanford University ), and did his doctorate on it in 1949 under Arnold Nordsieck (title of the doctoral thesis: Nutation of the nuclear magnetic moment and associated effects in spin ensembles ), with important suggestions from James H. Bartlett (1904–2000). In 1950 he worked as a postdoc with Charles P. Slichter at the University of Illinois; During this time Hahn discovered the NMR spin echo . 1950 to 1952 he worked in Bloch's NMR group at Stanford University. He then set up an NMR group at the IBM Thomas J. Watson Research Center (and Columbia University, which cooperates with the laboratory ), where he converted some of his earlier discoveries into patents. From 1955 he was an assistant professor at the University of California, Berkeley , where he received a full professorship in 1961 and retired in 1991. But he continued to research z. B. at Oxford University , in Canada and Japan and as a Humboldt Foundation fellow at the Max Planck Institute for Medical Research in Heidelberg .

Hahn is known as the discoverer of the spin echo . B. is used very essentially in magnetic resonance imaging (MRI). The response signals after a series of time-coordinated NMR high-frequency pulses with a well-defined phase relationship provide information about the relaxation phenomena of the nuclear spins in the solid or in the liquid and thus about the environment of the nuclear spins. From the 1960s he also did research on laser spectroscopy , where he and his student Samuel L. McCall discovered self-induced transparency, a non-linear effect ( soliton phenomenon) B. was used in experiments to "slow down light".

In the 1950s he worked firm consultant Harold Lyons also for scientific, also attended by Theodore Maiman , he brought to the company, at its rubidium - laser worked.

Awards

Hahn is an Honorary Fellow of Brasenose College, Oxford University. The Erwin L. Hahn Institute for Magnetic Resonance Imaging in Essen , founded in 2005, is named after him.

literature

  • Desmond MS Bagguley (Ed.): Pulsed Magnetic Resonance. NMR, ESR and Optics. A Recognition of Erwin L. Hahn . Oxford University Press, Oxford 1992, ISBN 0-19-853962-2 ( limited preview in Google Book Search).

Web links

Remarks

  1. ↑ Remembering Erwin Hahn. In: berkeley.edu. September 22, 2016. Retrieved February 9, 2018 .
  2. ↑ Although he had received a call to Los Alamos , he married at the same time and was therefore rejected for lack of accommodation. In his memoirs (Oral History Interview, Niels Bohr Institute) he also mentions that a fellow student from Purdue, Harry Dahglian, became the first victim of the nuclear weapons research project after exposure to unprotected experiments with plutonium.
  3. ↑ EL Hahn: Spin echoes . In: Phys Rev . tape 80 , no. 4 , 1950, p. 580-594 , doi : 10.1103 / PhysRev.80.580 .
  4. ^ Hahn and McCall: Self-Induced Transparency by Pulsed Coherent Light . In: Physical Review Letters . Volume 18, 1967, pp. 908-911. First they discovered the phenomenon in a computer calculation. As he noted in his oral history interview, the idea of ​​transferring techniques and concepts such as those of the Bloch equations from NMR into the laser field came from reading the article by Richard Feynman (with Hellwarth, Vernon Geometrical representation of the Schrödinger equation for solving maser problems , Journal of Applied Physics Vol. 28, 1957, p. 49) which emphasized the analogy of quantum mechanical two-state systems. The forerunner of the laser was z. B. the maser in the microwave range, but also many laser spectroscopy techniques had analogues according to Hahn in earlier NMR experiments.
personal data
SURNAME Hahn, Erwin
ALTERNATIVE NAMES Hahn, Erwin Louis (full name)
BRIEF DESCRIPTION American solid-state physicist
DATE OF BIRTH June 9, 1921
PLACE OF BIRTH Sharon , Pennsylvania , United States
DATE OF DEATH 20th September 2016