Paul R. Chagnon, professor emeritus of physics at the University of Notre Dame, died March 22 at his home in South Bend. He was 86. Chagnon taught physics and conducted research in nuclear physics at Notre Dame for 32 years before retiring in 1995. He published numerous articles on his research, and was admired as a stalwart of Notre Dame’s physics faculty. His teaching is honored annually at Notre Dame’s commencement ceremonies by the undergraduate Paul Chagnon Service Award.