"Beta-Neutrino Correlation in Nuclear Beta-Decay of Optically Trapped Sodium-21"
Reina Murayama
Lawrence Berkeley National Laboratory
Wednesday, March 9, 2005 -11 AM - 12:00 Noon in 375 Le Conte Hall
Abstract
From the observation of the continuous energy spectrum that led to Pauli's
postulate of the neutrino to Wu's discovery of parity symmetry violation in
Co-60, nuclear beta-decay has revealed many surprises. Using magneto-optically trapped
sodium-21 neutral atoms produced at the Berkeley 88" cyclotron, we are measuring
the beta-neutrino correlation coefficient. Optical traps offer a suitable environment
for precision measurements, and offer us isotopically pure sodium atoms
that are localized, nearly at rest, and relatively free from external perturbations.
We can reconstruct the decay kinematics from the time-of-flight of the daughter
nuclei from the trap to our detector. Our last measurement yielded a beta-neutrino
correlation coefficient, a_beta_nu, that disagrees by 3.6-sigma from the Standard
Model prediction. I will discuss the status of the experiment, our studies of
systematic effects, and possible explanations for this discrepancy.
