Match of Neutral and Charged Resolution

The cost of a cylindrical drift chamber is much less than that of a calorimeter, and not a strong function of radius. The charged particle transverse momentum resolution depends on where L is the measured transverse track length for a given axial 

The optimization of a detector geometry with these constraints tends to produce a calorimeter barrel inner radius of around 1 meter. Moving to larger radii is expensive, while reducing the radius tends either to reduce the space available for a particle identification system or to compromise charged particle momentum resolution to an unacceptable degree. 

Photon energy resolution The overall scale of resolution is set by crystal quality, light collection efficiency and iinih i mity, and leakage fluctuations. When using 

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