Hayes was born in
Killorglin on 12 November 1930. He was educated at
Synge Street CBS;
University College, Dublin; and the
University of Oxford. Hayes came to
St John's College, Oxford as an Overseas Scholar in 1955. At St John's, he was
Fellow and
Tutor from 1960 to 1987; and
Principal Bursar from 1977 to 1987. Hayes was a University Lecturer from 1962 to 1985, and Professor from 1985 to 1987. Hayes was
President of St John's College, Oxford from 1987 to 2001. He was
Pro-Vice-Chancellor of the
University of Oxford from 1990 to 2001. Hayes specialised in crystals, and studied imperfections in crystals and defects in solids. He investigated the spectroscopic signatures of imperfections in alkali halides and semiconductors, using varied research techniques that included inelastic light scattering (Raman and Brillouin spectroscopy), magneto-optics (
Zeeman effect),
nuclear magnetic resonance (NMR),
electron paramagnetic resonance (EPR) and
muon spin resonance (mu-SR). ==Personal life and death==