Hahn earned his doctorate in mathematics from Notre Dame in 1970 under the direction of Timothy O'Meara, the University's provost from 1978 to 1996.
writings on these topics include the books "The Classical Groups and K-Theory," with O'Meara
, and "Quadratic Algebras, Clifford Algebras and Arithmetic Witt Groups," and numerous research articles. In 2000, he was appointed director of the Honors Program for the College of Science.He
developed the two-semester calculus sequence Math 195 and 196 for College of Arts and Letters students in the honors program.This course evolved into his
1998 book "Basic Calculus: From Archimedes to Newton to its Role in Science," a text that was recently translated into Japanese.