Physics at Virginia

"Precision Measurements with the Neutron at Low Energies and High Intensities"

Dave Phillips , North Carolina State University
[Host: Don Crabb]
Precision measurements of neutron interactions at low energies and high intensities off er many avenues to search for physics beyond the Standard Model. Motivated by this particle physics impact, there are ongoing experimental programs which utilize cold and ultra-cold neutrons (UCN) to measure the neutron static electric dipole moment, neutron β-decay parameters, and possible new short range interactions. In this talk, we will focus on two such programs: a β-decay program at Los Alamos National Laboratory (LANL) utilizing UCNs and a proposed experiment to search for neutron-antineutron oscillations at Fermi National Accelerator Laboratory (FNAL). Modern studies of neutron β-decay o ffer an improved, nuclear structure independent determination of the CKM matrix element Vud through more precise measurements of the neutron lifetime and β -decay correlation coefficients. Vud is a critical input to a direct test of CKM matrix unitarity, which places stringent limits on extensions to the Standard Model for charged current interactions. This talk will begin with a summary of the UCNA experiment at LANL, the only experiment to perform a measurement of angular correlations in neutron β-decay (spin-electron asymmetry parameter A(E)) using UCN. We then present a recently proposed experiment to search for n − ‾n oscillations using free neutrons at FNAL, which would provide a sensitive window to probe for baryon number violating interactions with Δβ = 2, would provide insight into the origin of matter-antimatter asymmetry in the universe and would change our ideas on the energy scales relevant for quark-lepton uni cation and neutrino mass generation. Methods for an improved search for n − ‾n oscillations using free neutrons and recent detector characterization studies for such a search will be discussed.
Nuclear Physics Seminar
Tuesday, September 24, 2013
3:30 PM
Physics Building, Room 204
Note special room.

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