Trapped Atoms and Ions for Tests of the Charged Electroweak Interaction


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 β-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 β-ν-correlation in the β-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​ β​ , to 0.3% precision, which is comparable to or better than any other nuclear
measurement, including the neutron.

Speaker : 

Prof. Dan Melconian, PhD (Cyclotron Institute/Dept of Physics & Astronomy, Texas A&M University)


Presentation at 3:45 PM, NPL 178 Coffee and cookies starting at 3:30 PM