1991 Seaborg Award: John M. Alexander

Award Statement C&EN (Pages 1-2)

Alexander obtained a B.S. degree in math and chemistry from Davidson College, in North Carolina, in 1953 and a Ph.D. degree in physical and nuclear chemistry from Massachusetts Institute of Technology in 1956.

Along with his research colleagues, he was one of the early investigators of heavy-ion nuclear reactions. He helped provide the first extensive observations of the angular momentum dependence of neutron and photon emission from compound nuclei produced by heavy ion reactions along with systematics of first neutron energies and total γ-ray energies. These findings aided the theoretical development of statistical models that incorporate explicit treatments of angular momentum effects.

Alexander was the first to demonstrate the occurrence of incomplete fusion reactions along with complete fusion. More recently, he and his French colleagues have also studied the limits of energy deposition and thermalization into composite nuclei. In their recent work, they have used extensive particle emission studies and sophisticated model simulations to probe the nature of the hot nucleus and the range of applicability of statistical model descriptions of the deexcitation of such a nucleus. He and his coworkers have also led in the development of the probes of the extremely short lifetimes (~10^-20—10^-22 seconds) for particle emission from very hot nuclei.