Hofstadter, Robert (1915–1990)

US nuclear physicist who was awarded the Nobel Prize for Physics in 1961 for his work in scattering electrons in atomic nuclei, and for his pioneering studies of nuclear structure and the nuclear constituents, the proton and the neutron. He established that the proton and neutron were not pointlike, but had a definite volume and shape.

Educated in New York and Princeton, Hofstadter did his research in California after 1950. He demonstrated that the nucleus is composed of a high-energy core and a surrounding area of decreasing density. He helped to construct a new high-energy accelerator at Stanford University, with which he showed that the proton and the neutron have complex structures and cannot be considered elementary particles. See also quark.

Hofstadter was born in New York and educated at City College and Princeton. From 1950 he was at Stanford, where his early work involved scattering electrons from complex nuclei, such as gold. This produced accurate pictures of the charge distribution within nuclei. Gradually, smaller nuclei were studied by Hofstadter and his team, using electrons of increasing energy. By 1960, accurate data had been obtained for the proton and neutron, revealing the spatial distribution of charge and magnetization within these particles.