Performance of an electromagnetic liquid krypton calorimeter based on a ribbon electrode tower structure

The NA48 collaboration is preparing a new experiment at CERN aiming to study CP violation in the $K^{0}-K^{0}$ system with an accuracy of $2 \times 10^{−4}$ in the parameter $\Re(\epsilon'/\epsilon)$. Decays in two $\pi^{0}$'s will be recorded by a quasi-homogeneous liquid krypton calorimeter. A liquid krypton calorimeter has been chosen to combine good energy, position and time resolution with precise charge calibration and long-term stability. The prototype calorimeter incorporating the final design of the electrode read-out structure is presented in this paper. An energy resolution of $\simeq 3.5$%/$\sqrt{E}$ with a constant term smaller than 0.5% has been obtained. The time resolution was found to be better than 300 ps above 15 GeV.