Properties of a simple e/gamma detector consisting of a lead convertor and a hodoscope

The results of the calculations of coordinate resolution and hadron rejection factor for a simple e/gamma detector consisting of a lead convertor followed by a hodoscope are presented. For the simulation of showers, initiated in the converter by electrons and hadrons with energies upto 1 TeV GEANT4 is used. It is shown that the best coordinate resolution for electrons is achieved when the converter thickness is closed to the shower maximum. For example, at 200 GeV with 2 mm strip width hodoscope it is equal to sigma=89 microns provided a "truncated mean" coordinate estimation is used. The optimal thickness of the converter for hadron rejection is also close to tmax. For 200 GeV beam of electrons and protons the rejection factor of 10^-4 for 0.9 electron detection efficiency can be reached using only data on charged particles multiplicities. Information on the spatial distribution of the shower particles after the converter allows to enhance further the rejection by several times.