The primary goal of the proposed research program is to investigate the shell structure of exotic, neutron-rich nuclei by direct reactions. These kinds of reactions are an excellent tool to probe the single particle properties of nuclei and gain information on the nuclear wave functions. Comparisons of the experimental results with state-of-the-art theoretical calculations will give new insights on the nuclear potential such as the role of tensor forces and three-body components.
The broader impact of the proposed project includes building an active research program in nuclear structure physics at Central Michigan University. This project will provide opportunities for undergraduate and M.S. students to actively participate in experiments carried out at world leading research facilities. Students can apply their skill outside of the class room and gain new experience in simulating and analyzing experimental data, setting up data acquisition systems and developing a new particle detection system. The students will be expected to publish their results and present their research at national and international conferences.
Exotic nuclei provide an intersting playground to investigate the nature of the nuclear force. Effects of the tensor interaction and three body forces amongst nucleons may be enhanced compared to the well studied nuclei in the valley of stability. Direct reactions involivng radioactive ion beams in inverse kinematics are an excellent tool to probe the single particle properties of nuclei and gain information on the nuclear wave functions. Within this project we have investegated key nuclei in three regions of the nuclear chart by direct knockout and transfer reactions. Nucleon knockout reactions have been performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University using the GRETINA gamma-ray spectrometer in combination with the S800 Spectrograph. We have developed a new technique to study nuclei with long-lived excited states (isomers). The new device, IsoTagger, is now available for use the the NSCL and will become especially important as heavier beams become available with the future FRIB facility. At TRIUMF's radioactive beam facility ISAC-II accelerated beams suitable for transfer reactions where so far limited to light nuclei, with mass number A < 30. In summer 2013 and 2014 we have performed the first experiments with accelerated heavy radioactive beams. The study concentrated on one-neutron transfer reactions in the region around neutron-rich Sr isotopes. These first succesful experiments open a new path towards inbeam spectroscopy with beams from the future ARIEL facility at TRIUMF.