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Steven W. Yates
Professor and Chair (Nuclear Chemistry and Radiochemistry)
Characterization of collective motion of atomic nuclei
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| For many years it has been recognized that atomic nuclei in certain mass regions exhibit stable deformations, while those in other regions are essentially spherical. These spherical nuclei are often exceptionally stable, occur near closed shells (or magic numbers) of protons or neutrons, and display multiphonon vibrational excitations of quadrupole, octupole, and higher-order types. The nuclear chemistry research program at the University of Kentucky is focused on identifying and characterizing collective nuclear motions, e.g., vibrations, in nuclei. We utilize the inelastic neutron scattering (INS) reaction and gamma-ray emission spectroscopy to examine a variety of excited nuclear states. INS, coupled with detection of the de-exciting gamma rays, is distinctly superior to other nuclear reactions for the study of low-lying, low-spin states. |
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| With our unique methods, we can obtain exceptional sensitivity, and the INS reaction is not restricted by spin and parity selection rules. We have developed methods for measuring short (a few femtoseconds) nuclear lifetimes with the Doppler-shift attenuation method, and gamma-gamma coincidence measurements are performed routinely following INS. These unique advantages are currently being exploited to examine a variety of structural features of nuclei and to search for new, extraordinary nuclear modes. Working closely with Dr. Yates and his colleagues, the NSF-REU student will participate in one or more ongoing studies of the phenomena described above. For example, planned measurements include INS studies of 132XeF2 and 134XeF2. As our measurements usually involve around-the-clock radiation detection for a week or more, several students and postdoctoral fellows typically participate in each experiment. The REU student will be involved in all facets of setup, calibration, and execution of these experiments and in the analysis of a selected portion of the data obtained. In addition to being involved in the design, execution, and analysis of state-of-the-art nuclear chemistry experiments, the student will receive training in nuclear instrumentation and detectors, custom data acquisition and analysis programs, the use of vacuum systems, and the operation of a nuclear particle accelerator. |
Further details of Dr. Yates' work are given on the Chemistry website. |
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