Speaker
Description
Within the Standard model, the CKM matrix is predicted to be unitary. Testing this unitarity is therefore important to put limits on Beyond Standard Model physics contributions. The dominant matrix element for this test, Vud, is traditionally obtained from the corrected ft-values of superallowed pure Fermi beta transitions [1]. Another sensitive way to address Vud is through measuring the β-asymmetry parameter of the decay of 35Ar (Z=18) [2] which would help to further decrease the experimental uncertainty. To this end, a campaign (IS601) is ongoing at the VITO beamline at ISOLDE-CERN to determine this parameter.
For the first phase of the project, 35Ar was optically polarized and implanted in different stopper hosts (crystals). This phase functions as a design study for the final setup, detailing the efficiency of the laser polarization scheme and studying the performance of several crystal hosts for maintaining the ensemble polarization. This is done by verifying the accuracy of the optical pumping simulations and determining the relaxation time of the implanted polarized ensemble in the different crystals used.
This contribution will focus on the results obtained for the behavior of the relaxation time, including temperature and magnetic field dependency of the host crystals.
[1] Towner & Hardy, PR C 79 (2009) 055502
[2] O. Naviliat-Cuncic & N.S., Phys. Rev. Lett. 102 (2009) 142302
