MOTTELSON, BEN R.

MOTTELSON, BEN R. (1926– ), U.S. and Danish physicist and Nobel laureate was born in Chicago and received his B.S. from Purdue University, Indiana (1947), and his Ph.D., supervised by Julian Schwinger, from Harvard University (1950). He worked at the Institute for Theoretical Physics (later the Niels Bohr Institute) in Copenhagen (1950–53), followed by a period working with the theoretical group of the European Organization for Nuclear Research (CERN). In 1957 he was appointed professor at the newly established Nordic Institute for Theoretical Atomic Physics in the same city (1957). With Aage Bohr, Mottelson investigated the structure of nuclei by theoretical and experimental means and established that a rotational spectrum and particle pairing account for the energy levels in nuclei. These observations had an important influence on subsequent particle physics and the elucidation of superconductivity. Mottelson and Bohr were awarded the 1975 Nobel Prize in physics, shared with James Rainwater. Mottelson subsequently made important contributions to understanding nuclear pairing and rotation and shell structure in metallic atom clusters. He married Nancy Jane Reno (1948) and they and their three children became Danish citizens in 1971. (Michael Denman (2nd ed.)