Lawrence Berkeley National Laboratory

We have limited a CPT-violating correlation in annihilations of polarized ortho-positronium. We searched for an asymmetry in the triple correlations dot k1 cross k2, where k1 and k2 are the two largest photon momenta, and s is the spin of the positronium. Using the Gammasphere array of Compton-suppressed high-purity germanium detectors, we detected 2.65e7 events of ortho-Ps annihila tion. The amplitude of a CPT-violating asymmetry in the data set is found to be 0.0026 plus or minus 0.0031, a factor of 6 smaller than previous experiments.