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Physics and Astronomy

Physics & Astronomy Colloquium

3:30 PM, Friday, April 11, 2014
Room 155, Chem-Phys Building

Dr. Geoff Greene
University of Tennessee, Knoxville


TITLE

While neutrons within nuclei may be stable, the free neutron is unstable against beta decay and has a mean lifetime of ~15min. Free neutron beta decay is, perhaps, the simplest weak nuclear process as it is uncomplicated by many body effects that are present in the decay of nuclei. As a result, it can be directly understood in terms of rather simple fundamental weak interaction theory. Additionally, because free neutron decay is the "prototype" for all nuclear beta decays, the neutron lifetime is a fundamental parameter whose value is important not only in nuclear physics, but also in astrophysics, cosmology, and particle physics. I will give an introduction to the theory of weak nuclear decay and briefly discuss the importance of the neutron lifetime as a parameter in the Big Bang. A review of the experimental strategies for the measurement of the neutron lifetime will be given as well as a discussion of the puzzling discrepancy among the measurements with the lowest quoted uncertainty. Finally, I present a very new result recently obtained at the NIST Cold Neutron Research Facility in Gaithersburg Md.

Refreshments will be served in CP 179 at 3:15 PM