Professor Donald Perkins CBE FRS
Donald Perkins made significant contributions to the physics of elementary particles and nuclear interactions at extreme energies such as may be observed in cosmic radiation. Donald was first to observe the nuclear capture of a negative pi meson. He made a series of brilliant studies of nuclear transmutations in a very wide range of energy, from 102 GeV (billion electron volts) to 106 GeV. In this field his contributions, with Peter Fowler, to the interpretation of electron–photon cascades in lead-emulsion stacks in terms of particle production at ultrahigh energies are particularly noteworthy. Donald also made valuable contributions to technical methods for measuring the ionisation produced by particles in photographic emulsion.