Nier, Alfred O(tto) C(arl) (1911–1994)

US physicist. Nier developed the high-resolution mass spectrometer to study rare isotopes, and (1940) separated and determined the fissionability of uranium-235.

He was born in St Paul, Minnesota. Nier was a fellow at Harvard (1936–38), taught at the University of Minnesota (1938–43), and became a physicist at Kellex Corporation, New York, before returning to Minnesota as a professor (1945–80).