Three dimensional parametrization of electromagnetic shower in alpha magnetic spectrometer II ECAL

We develop an empirical formula to parameterize the 3-dimension (3D) distribution of electromagnetic showers in the Alpha Magnetic Spectrometer II electromagnetic calorimeter(ECAL). The formula was verified by ECAL test beam data in 2002 and found to perform well. The distribution of electron showers in the ECAL are well described by the formula, which has parameters that allow one to determine the 3D shape of electromagnetic showers in the ECAL. We use this formula to correct for lateral energy leakage and dead channels in the ECAL; good results are obtained.