|< Lew Riley||Nuclear Structure Research|
Experiments that probe nuclear structure are generally done at large accelerator facilities. We do our experimental work at the accelerator facilities at Florida State University (FSU) and the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. At the NSCL, we study exotic nuclei using fast beams (> 50 MeV/nucleon) in reactions including inverse-kinematics proton scattering, Coulomb excitation, single-nucleon knockout, and fragmentation. These reactions often produce nuclei in excited states which rapidly de-excite by emitting gamma rays. We measure the intensities and energies of these gamma rays to deduce properties of the excited states.
We study shell structure by measuring proton and neutron contributions to collective nuclear excitations. Collective excitations are excited states in which many protons and neutrons participate. The cartoon at right is an illustration of a collective quadrupole shape vibration, a common low-lying collective excitation. In the simplest collective picture, the nucleus us an incompressible "liquid drop" which undergoes collective shape vibrations and rotations. This purely collective model predicts equal proton and neutron contributions to excitations. However, the nuclear shell model, which focuses on single particle behavior, predicts that protons and neutrons can be trapped in closed shells and that valence nucleons dominate low-lying excited states. Hence, differences between proton and neutron behavior in collective excitations are evidence of underlying shell structure.
This material is based upon work supported by the National Science Foundation under Grant Nos. PHY-0355129, PHY-0098774/ PHY-0342281, PHY-0653323, PHY-0922615, and PHY-0969002. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
Jess and Nick at the Conference Experience for Undergraduates poster session of the Fall 2010 APS-DNP Meeting in Santa Fe, NM.
Brett and Jess at the October 2009 3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan in Hawaii.
Brett and Dan the April 2009 Meeting of the American Physical Society in Denver, CO.
Kelly and Jesse at the Conference Experience for Undergraduates poster session of the Fall 2005 American Physical Society/Division of Nuclear Physics Meeting in Nashville, TN.
Darren at the Conference Experience for Undergraduates poster session of the Fall 2005 Second Joint Meeting of the Nuclear Physics Divisions of the American Physical Society and The Physical Society of Japan in Maui, HI.
Mike and Majd at the Conference Experience for Undergraduates poster session of the Fall 2004 APS-DNP Meeting in Chicago, IL.
We spent the first two weeks of June at the NSCL working with Alexandra Gade, Daniel Bazin, and Wilhelm Mueller on the analysis and learning to install and use the NSCL SpecTcl software package to sort the data. We then completed the analysis at Ursinus College.
Tabatha and Majd at the Conference Experience for Undergraduates poster session of the Fall 2003 APS-DNP Meeting in Tuscon, AZ.
|Copyright © 2000-2003, Lewis A. Riley|