An Observation of direct CP violation - epsilon prime/epsilon result from KTeV

We report the first KTeV measurement for the search of direct-CP violation by using 23% of the data sample collected in the 1996-97 fixed target run at Fermilab. The result is, Re({epsilon}{prime}/{epsilon}) = (28.0 {+-} 4.1) x 10{sup -4}, nearly 7{delta} above zero obtained by a blind analysis. This firmly establishes the long-sought ''direct-CP violation'' effect in the two-pion system ({pi}{sup +}{pi}{sup -} versus {pi}{sup 0}{pi}{sup 0}) of neutral kaon decays. Other new measurements of {Delta}m, {tau}{sub s}, {Delta}{phi} and a limit on the diurnal variation of {phi}{sub +-} for testing CPT invariance from the same data sample are also presented.