Department of Physics & Astronomy

Gregory Christian

Assistant Professor

Gregory Christian

Biography

Dr. Christian's work is centered around using direct nuclear reactions as a tool for studying both nuclear astrophysics and nuclear structure. On the astrophysics side, Dr. Christian, his group, and their collaborators use nucleon transfer reactions to indirectly constrain the rates of key reactions driving nucleosynthesis in explosive stellar environments, such as novae, supernovae, and X-ray bursts. Ultimately, this work strives to answer "big picture" questions such as "Where do the chemical elements come from?" and "What are the processes driving stellar evolution and stellar explosions?". On the structure side, the focus of Dr. Christian's group is on using nucleon transfer reactions to populate and study excited states in "exotic" nuclei - or nuclei with extreme neutron-to-proton ratios, far away from stability. These nuclei display a varity of fasciniting phenomena, such as neutron "halos", or extended matter radii, as well as exotic decay modes including "dineutron emission", or the emission of correlated neutron pairs. Most of Dr. Christian's work is performed at the Texas A&M University Cyclotron Institute, a world-class facility conveniently located only steps away from the Physics & Astronomy building. Dr. Christian is particularly keen on doing experiments with the re-accelerated beams that will be available as part of the Cyclotron Institute's upgrade project. Some experiments are also performed off campus, at user facilities such as TRIUMF in Vancouver, Canada and the Facility for Rare Isotope beams at Michigan State University. Much of Dr. Christian's current experimental program focuses on using the TIARA silicon detector array to measure (d,p) single-neutron transfer reactions, as part of an international collaboration with Physicists from the University of Surrey in the UK. Future work will involve measurement of (d,n) single-proton transfer reactions, as well as the breakup of unbound resonant states in extremely neutron-rich nuclei. In addition to experimental nuclear physics, Dr. Christian takes an active interest in developing new detectors and experimental techniques for nuclear physics. Many of these projects would be appropriate for students interested in an Applied Physics PhD. In the near future, his group is beginning the construction of a next-generation neutron detector which borrows techniques from the world of medical physics to significantly enhance the position and energy resolution for detecting neutrons with energies greater than 1 MeV.