Test of time-reversal invariance in 131Xe

An experiment has been performed to test the time-reversal symmetry in the emission of the mixed E2 and M1 364 keV γ transition in 131Xe. The phase angle η between the multipole transition amplitudes was measured by observing the angular distribution of the linear polarization of the γ ray emitted from a 131I source polarized at low temperature (30 mK obtained with a dilution refrigerator). A Compton polarimeter was used to measure linear polarization. The 131Xe transition was selected to minimize atomic final state effects which simulate time-reversal violation. A value sinη=(-1.1±1.1)×10^-3 was obtained for the transition, consistent with time-reversal invariance.