February 5, 1915–November 17, 1990
BY JEROME I.FRIEDMAN AND WILLIAM A.LITTLE
ROBERT HOFSTADTER WAS BORN in New York City, educated on the East Coast, but spent most of his academic career at Stanford University. He is best known for his work on determining the distribution of charge and magnetic moment in the nuclei of atoms and of the nucleons themselves, for which he was awarded a Nobel Prize in 1961. He extended the work done in the early part of the twentieth century by Ernest Rutherford, who had shown that atoms were composite, containing electrons and a nucleus many thousands of times smaller than the atom. Rutherford discovered this by scattering alpha particles from thin metal foils of the elements and measuring the number of particles scattered as a function of the angle. The surprisingly large number of particles that were scattered through large angles could only be explained by collisions with a heavy, very small, perhaps point-like, positively charged object, which he called the nucleus.
Some 40 years later Hofstadter determined the internal structure of such nuclei by scattering high-energy electrons from thin targets and measuring the distribution of the number of these electrons as a function of angle. In these experiments he built on earlier work by others on electron-