Study of the Effects of Data Reduction Algorithms on Physics Reconsruction in the CMS ECAL

A study has been performed comparing various schemes for reducing the data volume of a level 1 accepted event in the CMS electromagnetic calorimeter. All the schemes proved capable of reducing the data volume to an appropriate level. However, using simple zero suppression has been shown to introduce noticeable non-linearities in the energy scale which were absent when using a selective readout scheme like the one proposed in this paper. Rear leakage of the electro-magnetic cascade from the rear face of the detector crystals has also been investigated and shown to have a non-negligible effect for high energy photons.