Polykarp Kusch (born 26.01.1911) is an American physicist and a member of the National Academy of Sciences (1956).
He was born in Blankenburg (now in the GDR) and has lived
in the USA since 1912. He graduated from the Case Institute of Technology (1931). In 1931-36 he worked at the University of Illinois, in 1936 —37 at the University of Minnesota, and in 1937 —72 at Columbia University (professor from 1949). From 1972 he has been professor at the University of Texas (Dallas).
His research was in the field of atomic, molecular and nuclear physics. In particular, he studied atomic, molecular and nuclear properties and phenomena by the method of molecular beams. He measured the hyperfine splitting of the ground state of atomic hydrogen and determined the ratio of the magnetic moment of the proton to the orbital magnetic moment of the electron in the atom. In 1948 he measured the anomalous magnetic moment of the electron with high precision (Nobel Prize, 1955).