Robert Hofstadter (born 5.02.1915) is an American experimental physicist and a member of the National Academy of Sciences (1958). He was born in New York. He graduated from Princeton University (1938), where he worked in 1946 — 50. Since 1950 he has been at Stanford University (professor since 1954 and in 1967 — 74 director of the High Energy Physics Laboratory).
His work concerned nuclear physics and nuclear engineering, optics, accelerator technology and high-energy physics. In 1939—40 he took part in building a large Van de Graaff generator. In 1948 he designed a scintillation counter based on crystals of sodium iodide activated with thallium, which found wide use in gamma spectroscopy, and also a number of neutron and X-ray counters.
In experiments on the scattering of high-energy electrons by nucleons (1955 — 58) he obtained for the first time quantitative information on the distribution of electric charge and magnetic moment inside the nucleon and on the size of the nucleon, and made the first determinations of nucleon form factors; in particular, in 1957 he determined the charge and magnetic form factors of the proton, and in 1958 the magnetic form factor of the neutron (Nobel Prize, 1961).