New measurement of the CP violation parameter

We have measured the {ital CP} violation parameter {eta}{sub +{minus}{gamma}} in a neutral kaon experiment, E773, at Fermilab. This parameter characterizes {ital CP} violation in the decay {ital K}{sub {ital L}}{r_arrow}{pi}{sup +}{pi}{sup {minus}}{gamma}. Kaon decays into {pi}{sup +}{pi}{sup {minus}} collected simultaneously were used for normalization. Our result is {vert_bar}{eta}{sub +{minus}{gamma}}{vert_bar}=[2.359 {plus_minus} 0.062(stat) {plus_minus} 0.040(syst)] {times} 10{sup {minus}3} with a phase {phi}{sub +{minus}{gamma}} = [43.8 {plus_minus} 3.5(stat) {times} 1.9(syst){degree}]. The prediction that {eta}{sub +{minus}{gamma}} should be very close to {eta}{sub +{minus}} is supported by our result.