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Trapped Atoms and Ions for Tests of the Charged Electroweak Interaction

Dan Melconian (Cyclotron Institute & Texas A&M University)
Thursday, July 19, 2018 - 3:45pm
NPL 178

Nuclear decay has a long-standing history of shaping and testing the standard model of particle physics, and it continues to this day with elegant, ultra-precise low-energy nuclear measurements. Experiments observing the angular correlations between the electron, neutrino and recoil momenta following the decay of (un)polarized nuclei can be used to search for exotic currents contributing to the dominant V−A structure of the weak interaction. Precision measurements of the correlation parameters to < 0.1% would be sensitive to (or meaningfully constrain) new physics, complementing other searches at large-scale facilities like the LHC. Ion and atom traps provide an ideal source of very cold, short-lived radioactive nuclei in an extremely clean and open environment. As such, they are invaluable tools for precision measurements of B-decay parameters. This talk will focus on two such efforts. The TAMUTRAP facility at the Cyclotron Institute, Texas A&M University, will utilize an upgrade to the recently commissioned cylindrical Penning trap – already the world’s largest with an inner diameter of 90 mm – to search for scalar currents via the B-v-correlation in the B-delayed proton decay of T = 2 nuclei. The other effort, based at TRIUMF in Vancouver, Canada, utilizes neutral atom-trapping techniques with optical pumping methods to highly polarize (> 99%) 37 K atoms. Recently, we determined the asymmetry parameter, A B , to 0.3% precision, which is comparable to or better than any other nuclear measurement, including the neutron.

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