Alan Watson’s work focuses on cosmic rays of the highest energy. Alan played a central role in the construction and operation of the extensive air shower array at Haverah Park near Leeds — an array which led the world for two decades in studies of cosmic rays of the highest energies. Notable firsts included the demonstration that the energy spectrum did not fall at a few times 10¹⁹ electron volts, as expected from interactions of the extragalactic particles with the cosmic microwave background. Other work has included studies of cosmic rays in the inhospitable region of the South Pole.

Alan was co-spokesperson, with James W. Cronin from Chicago, of the Pierre Auger Observatory. He is now an Emeritus Spokesperson of this observatory and is working with colleagues in Granada, Lisbon and Santiago de Compostela to develop new methods to discover the mass of the highest energy cosmic rays. For his PhD, Alan studied the condensation of water vapour — atmospheric science, and particularly lightning, remains of interest to him.