Dempster, A. J.

Dempster, A. J. (Arthur Jeffrey)

(1886–1950) physicist; born in Toronto, Ontario, Canada. He came to the U.S.A. to study at the University of Chicago (1914). He spent his teaching and research career there (1917–50), except for the years that he worked on the Manhattan Project (1941–45). He made major contributions to the field of mass spectroscopy and was the discoverer of uranium-235 (1935).