A precise measurement of the direct CP violation parameter $\mathrm{Re}(\varepsilon'/\varepsilon)$

The direct CP violation parameter \(\mathrm{Re}(\varepsilon'/\varepsilon)\) has been measured from the decay rates of neutral kaons into two pions using the NA48 detector at the CERN SPS. With 3.3 million \(K_L \rightarrow \pi^0 \pi^0\) events collected during the 1998 and 1999 running periods, a result of \(\mathrm{Re}(\varepsilon'/\varepsilon) = (15.0 \pm 2.7)\times 10^{-4}\) has been obtained. The result combined with the published 1997 sample is \(\mathrm{Re}(\varepsilon'/\varepsilon) = (15.3 \pm 2.6)\times 10^{-4}\).