U.S. physicist whose contributions to nuclear physics include the discovery that the nucleus of the deuterium atom consists of a proton and a neutron.

While studying at Cambridge University, Goldhaber, in collaboration with James Chadwick (Chadwick, Sir James), discovered (1934) the nuclear photoelectric effect (photodisintegration) (the disintegration of a nucleus by high-energy X-rays or gamma rays). This discovery later provided evidence that the neutron is heavier than the proton. While studying slow neutrons, they discovered the neutron-induced disintegrations of the nuclei of lithium, boron, and nitrogen. Goldhaber also showed the usefulness of photographic emulsions in recording the tracks of particles formed in nuclear reactions. The slow-neutron scattering studies he made in 1937 were essential to the development of the first nuclear reactors.

In 1938 Goldhaber joined the staff of the University of Illinois, Urbana, where, with his wife, Gertrude Scharff Goldhaber (also a physicist), he demonstrated that electrons and beta rays are the same. In 1940 he discovered that beryllium is a good moderator (a material that slows down fast neutrons so they more readily split uranium atoms), and it has since been widely used in nuclear reactors.

In 1950 Goldhaber went to Brookhaven National Laboratory, Upton, N.Y., where, seven years later, with the U.S. physicist L. Grodzins, he discovered that the neutrino has a left-handed spin. He became director of Brookhaven in 1961, retiring in 1973.