University of Toronto
Physics Department
Quantum Optics and Condensed Matter

SPECIAL SEMINAR

Abstract

 Lasers can be used to cool and trap neutral atoms.  Such techniques won the 1997 Nobel Prize for Chu, Phillips, and Cohen-Tannoudji, and are revolutionizing a number of subfields of atomic physics.  At TRIUMF, we are applying these techniques to a rather different problem, the study of nuclear beta decay.  We use a Magneto-Optical Trap to capture beta-decaying nuclei and hold them suspended in space, free of any backing materials.  By detecting the low-energy nuclear recoils in coincidence with the beta, we can reconstruct the neutrino momentum.  The angular distribution of the neutrinos with respect to the beta direction is predicted by the Standard Model, and deviations from that prediction are sensitive to new interactions.  Among the atomic physics challenges is understanding the microchannel plate efficiency for detecting neutral Ar atoms, neutral, Ar metastables, and Ar ions, all of which are produced in the beta decay.  The trapping will be described, along with other atomic techniques to polarize nuclei to test whether parity is maximally violated in the charged weak interaction.  Preliminary measurements of the beta-neutrino angular distribution from a spin-0 nucleus will be shown: our goal is to set limits on the existence of new scalar bosons complementary to those set by high-energy colliders.
 
 

Local Host:  Aephraim Steinberg  (416-978-0713)

See   http://www.physics.utoronto.ca/~qocmp