Test of Time Reversal Symmetry using polarized⁸Li at TRIUMF-ISAC

Abstract

A new experimental project called MTV (Mott Polarimetry for T-Violation Experiment), is running at TRIUMF. It aims to achieve the highest precision test of time reversal symmetry in polarized nuclear beta decay by measuring a triple correlation (R-correlation), motivated to search a new physics beyond the standard model. It is because the CKM predicts negligible effects on the u-d quark system. In this experiment, the existence of non-zero transverse electron polarization is examined utilizing the analyzing power of Mott scattering from a thin metal foil. Backward scattering electron tracks are measured using a multi-wire drift chamber event-by-event for the first time. The tracking device eliminates the largest systematic effect, which has been limiting the sensitivity of previous studies. The MTV experiment was commissioned at TRIUMF-ISAC in 2009 using an 80% polarized 8Li beam at 10 Mpps resulting in 3.6% precision on the R-parameter, after performing a feasibility test at KEK-TRIAC in 2008 using an 8% polarized beam at 100 kpps yielding 41% statistical precision. In 2010, a physics production run is scheduled, aiming to reach below 0.1% precision. In this document, the preparation status for the 2010 run and results from the commissioning run are described.