Search for CP-Violation in $K_{S} \to 3\pi^{0}$ decays with the NA48 detector

The decay $K_{S} \to 3\pi^{0}$ is forbidden by CP conservation. Using a sample of more than 6 million $K \to 3\pi^{0}$ decays, the NA48 Collaboration has improved the limit on $\eta_{000} = A(K_{S} \to 3\pi^{0})/A(K_{L} \to 3\pi^{0})$ and on the branching ratio $Br(K_{S} \to 3\pi^{0})$ by about one order of magnitude. Using this result and the Bell-Steinberger relation, a new limit on the equality of the $K^{0}$ and $\bar{K^{0}}$ masses is obtained improving by about 40% the test of CPT conservation in the mixing of neutral kaons.