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Nobel 1961

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The Electron-Scattering Method and Its Application to the Structure of Nuclei and Nucleons

Recoilless Nuclear Resonance Absorption of Gamma Radiation

"for his pioneering studies of electron scattering in atomic nuclei and for his thereby achieved discoveries concerning the structure of the nucleons"

"for his researches concerning the resonance absorption of gamma radiation and his discovery in this connection of the effect which bears his name"

Robert Hofstadter	Rudolf Ludwig Mössbauer

1/2 of the prize	1/2 of the prize
USA	Federal Republic of Germany
Stanford University Stanford, CA, USA	Technical University Munich, Federal Republic of Germany; California Institute of Technology (Caltech) Pasadena, CA, USA
b. 1915 d. 1990	b. 1929

Biography: Robert Hofstadter

Robert Hofstadter, Professor of Physics at Stanford University, was born in New York, N.Y., of parents Louis Hofstadter and Henrietta Koenigsberg, on February 5, 1915.

Hofstadter attended elementary and high schools in New York City, and was graduated in 1935 from the College of the City of New York with the B.S. degree, magna cum laude.

On graduation from college Hofstadter received the Kenyon Prize in Mathematics and Physics, and a little later the Coffin Fellowship, awarded by the General Electric Company. He went to graduate school at Princeton University where he studied physics from 1935 - 1938, and received both the M.A. and Ph.D. degrees in 1938 from that institution. His Ph.D. work was concerned with infrared spectra of simple organic molecules, and in particular, with the partial elucidation of the structure of the now well-known "hydrogen bond". In 1938 - 1939 he was awarded a Procter Fellowship at Princeton University for postdoctoral work, at which time he began a study of photoconductivity in willemite crystals. This work led to the discovery, with R. Herman, of the warm-up dark currents which demonstrated the existence of trapping states in crystals. In 1939 Hofstadter received the Harrison Fellowship at the University of Pennsylvania where he helped to construct a large Van de Graaff machine for nuclear research. At Pennsylvania he first met L. I. Schiff, who has been a friend and colleague for many years.

During the war years Hofstadter worked first at the National Bureau of Standards and later at the Norden Laboratory Corporation. He left industry at the end of the war to become Assistant Professor of Physics at Princeton University. At Princeton he carried out research on crystal conduction counters, on the Compton effect, and on scintillation counters. In 1948 he discovered that sodium iodide, activated by thallium, made an excellent scintillation counter. In 1950, with J. A. McIntyre, he found that well-formed crystals of this material provided remarkable energy-measuring devices for gamma rays and energetic particles and thus could be used as spectrometers in addition to gamma-ray and particle counters of high efficiency.

In 1950 Hofstadter left Princeton to become Associate Professor of Physics at Stanford University where he initiated a program on the scattering of energetic electrons from the linear accelerator, invented by W. W. Hansen, which was then under construction. While building equipment for the electron-scattering experiments, he continued working on scintillation counters and developed new detectors for neutrons and X-rays. High-speed inorganic (CsF) and useful Cerenkov (TlCl) counters were discovered at Stanford. Other studies carried out in the early years at Stanford were concerned with cosmic rays and with cascade showers generated by high-speed electrons.

After 1953 electron-scattering measurements became Hofstadter's principal interest. With students and colleagues he investigated the charge distribution in atomic nuclei and afterwards the charge and magnetic moment distributions in the proton and neutron. The electron-scattering method was used to find the size and surface thickness parameters of nuclei. Many of the principal results on the proton and neutron were obtained in the years 1954-1957. Since 1957 emphasis in the research program has been placed on making more precise studies of the nucleon form factors. This work is still in progress.

Hofstadter was elected to the National Academy of Sciences (U.S.A.) in 1958 and was named California Scientist of the Year in 1959. He has also been a Guggenheim Fellow (1958 - 1959) and spent one year at CERN in Geneva, Switzerland, on sabbatical leave.

In 1942 he married Nancy Givan of Baltimore, Maryland, and they have a son, Douglas, and two daughters, Laura and Mary.

Biography: Rudolf Ludwig Mössbauer

Rudolf Ludwig Mössbauer was born in Munich on the 31st of January 1929, the son of Ludwig Mössbauer and his wife Erna, née Ernst. He was educated at the "Oberschule" (non-classical secondary school) in Munich-Pasing and left after matriculating in I948. After working for one year in industrial laboratories, he started reading physics at the Technical University (Technische Hochschule) in Munich in 1949 and passed his intermediate degree examinations in 1952. During the years 1953 and 1954 he completed his thesis at the Laboratory for Applied Physics at the Technical University in Munich, at the same time acting as assistant lecturer at its Institute of Mathematics. From 1955 to 1957 he worked on his thesis for the doctorate and carried out a series of investigations at the Institute for Physics of the Max Planck Institute for Medical Research in Heidelberg, in the course of which he carried out the first experimental observation of the phenomenon of Recoilless Nuclear Resonance Absorption. In January 1958 he received his degree under Professor Maier-Leibnitz at the Technical University in Munich. In 1958, again at the Max Planck Institute in Heidelberg, he provided the direct experimental evidence of the existence of Recoilless Nuclear Resonance Absorption. For the year 1959 he was appointed scientific assistant at the Technical University in Munich.¹ He accepted an invitation by the California Institute of Technology in Pasadena, U.S.A., in 1960 and there continued his investigations of gamma absorption, at first as Research Fellow and later as Senior Research Fellow. He was appointed Professor of Physics at the California Institute of Technology in 1961.

From the year 1953 onwards his main work was directed towards the study of absorption of gamma rays in matter, in particular the study of nuclear resonance absorption. This led to the discovery of Recoilless Nuclear Resonance Absorption and its theoretical interpretation. During the last few years he has been investigating problems of nuclear physics and of solid state physics by applying already previously established methods.

His work in the field of Recoilless Nuclear Resonance Absorption has been rewarded by the following prizes: Prize of the Research Corporation New York (1960); Röntgen Prize of the University of Giessen (1961); Elliot Cresson Medal, Franklin Institute (1961).

He is married to Elisabeth, née Pritz, and has a daughter, Susi.²

From Nobel Lectures, Physics 1942-1962, Elsevier Publishing Company, Amsterdam, 1964

This autobiography/biography was first published in the book series Les Prix Nobel. It was later edited and republished in Nobel Lectures. To cite this document, always state the source as shown above.

1. Meanwhile, Richard Feynman had become aware of Mössbauer's work on nuclear resonance absorption and made him accept a position as research fellow at the California Institute of Technology (Caltech) in California, USA, where he quickly became senior research fellow, and full professor in early 1962. It was there and then, when in the small hours of the day he received the phone call from Stockholm that he had been awarded the 1961 Nobel Prize for his work on Recoilless Nuclear Resonance Absorption of Gamma Radiation (1961 co-winner was R. Hofstadter), which proved to be the crucial basis for the discovery of nuclear resonance fluorescence, becoming known as Mössbauer Effect. This ME has since played an important role in applications in science far beyond physics. (Updated by the Laureate, May 2005.)

2. He had two more children with Elisabeth, a son, Peter, and a daughter, Regine. Later, he married Christel, née Braun. (Updated by the Laureate, May 2005.)

Addendum, May 2005

In 1965 Rudolf Mössbauer accepted a call from the Bavarian Ministry of Culture, Education & Research to become full professor at Technische Universität München, where his scientific interests shifted from nuclear research towards neutrino physics. It was in 1972 that he went to Grenoble (France) to be Director of the Institute Max von Laue-Paul Langevin (ILL), and the German-French-British High-Flux Reactor. After the five years' directorship period he returned to Munich in 1977, only to find his modernisation of the faculty - a prerequisite for his accepting to waive a US career for Munich - had meanwhile been reversed. Nevertheless, Mössbauer turned down several calls from other universities and Max Planck Institutes, and continued with his research on the "neutrino puzzle" (in particular neutrino oscillation experiments at Goesgen/Switzerland and solar neutrino experiments (gallex) at the Gran Sasso Underground Laboratories in Italy) until his retirement in 1997 but also beyond. In fact, it is still keeping him rather busy today, leaving him less time than anticipated for his hobbies hiking, classical piano, and photography, which stand for many anecdotes.

He holds numerous awards, medals, and prizes from universities and institutions the world over, as well as 13 honorary professorships at the most renowned universities in Europe, and abroad.

Nobel Lecture: Robert Hofstadter

The Electron-Scattering Method and Its Application to the Structure of Nuclei and Nucleons

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