In 1950–1951, James Rainwater and Aage Bohr had developed models of the atomic nucleus which began to take into account the behaviour of the individual nucleons. These models, which moved beyond the simpler liquid drop treatment of the nucleus as having effectively no internal structure, were the first models which could explain a number of nuclear properties, including the non-spherical distribution of charge in certain nuclei. Mottelson worked with Aage Bohr to compare the theoretical models with experimental data. In 1952–1953, Bohr and Mottelson published a series of papers demonstrating close agreement between theory and experiment, for example showing that the energy levels of certain nuclei could be described by a rotation spectrum.[6][7][8][9] This work stimulated new theoretical and experimental studies.
In the summer of 1957, David Pines visited Copenhagen, and introduced Bohr and Mottelson to the pairing effect developed in theories of superconductivity, which inspired them to introduce a similar pairing effect to explain the differences in the energy levels between even and odd atomic nuclei.[10]
Nobel Prize (1975)
Rainwater, Bohr and Mottelson were jointly awarded the 1975 Nobel Prize in Physics "for the discovery of the connection between collective motion and particle motion in atomic nuclei and the development of the theory of the structure of the atomic nucleus based on this connection".[11]
Post–Nobel Prize work
Bohr and Mottelson continued to work together, publishing a two-volume monograph, Nuclear Structure. The first volume, Single-Particle Motion, appeared in 1969,[12][13] and the second volume, Nuclear Deformations, in 1975.[14][15]
Mottelson was a dual citizen, as he held both Danish and American passports. He lived in Copenhagen. Mottelson was married to Nancy Jane Reno from 1948 until her death in 1975, and they had two sons and one daughter. Mottelson then married Britta Marger Siegumfeldt in 1983.[22]
^Bohr, A.; Mottelson, B. R.; Pines, D. (15 May 1958). "Possible Analogy between the Excitation Spectra of Nuclei and Those of the Superconducting Metallic State". Physical Review. 110 (4). American Physical Society (APS): 936–938. Bibcode:1958PhRv..110..936B. doi:10.1103/physrev.110.936. ISSN0031-899X.