Expected Energy and Angular Resolution

The 11 any e e)iive rting pheitem with E Ef will be ntire ly h)St, anel be low 2Ec at least one e)f the e emve rsion le ptems will always be h)st.. s the phe)teui e ne rgy incre ase s further, this be havie)r will graelually e hange to the de tee-tie)u e f beith le ptems, either se parate fl or me rge e.  

For the endcap region, cluster broadening will be the main effect except at very low energies. For example, a 200 MeV conversion originating 25 cm before reaching the outer endcap radius will deviate from the photon impact point by about 3 cm. However, the conversion probability must also include the drift chamber endplates and (in the backward direction) readout cards and cables. 

Obviously, for photon analysis, the less material in front of the calorimeter the better. 

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