Test of Time Reversal Invariance in the Decay K+ → π0μ+ν

The T violating parameter, i(xi), of the decay K+ --> pi(0)mu(+)upsilon, has been determined in KEK experiment E246 from a measurement of the transverse mu(+) polarization, PT. The experiment is the first to use stopped K+ which allows a null test, formation of a double ratio for PT, and enhances the ratio i(xi)/P-T. The results from the 1996-1997 data are: i(xi) = -0.013 +/- 0.016 +/- 0.003 similar to 3P(T). The first error, due to statistics, dominates over the second which is due to systematics. Considerably more data taken in 1998 is under analysis and additional running time has been approved by KEK.