The Science Enjoyed by Professor Alec T. Stewart

Late Professor Stewart initiated and shaped the International Conference on Positron Annihilation (ICPA) series. As a first-generation experimental positron-annihilation scientist, he made full use of the angular correlation of annihilation radiation (ACAR) method. He applied this method to study Fermi surfaces of metals, positron wave-functions in crystals, positron-electron and -phonon many-body interactions, and the vacancy formation energy in solids. He also studied with this method positronium in liquids and solids (T. Hyodo, J. Phys. Conf. Series, 618 (2015) 012002). All these studies enjoyed by Professor Stewart will long be remembered by the positron study community.