Optimisation of the Longitudinal Light Collection Uniformity in the CMS Endcap Calorimeter

The effects of non-uniform light collection in PbWO4 crystals using the CMS endcap ECAL are presented. The preshower is included in the simulation. The possibility of having shorter crystals than in the barrel ECAL is also considered. The results are quite similar to the ones found in a previous study. The slope at shower maximum is tightly constrained, as is the slope at the very front of the crystals due to the presense of the preshower. A small positive slope at the back of the crystals helps in compensating for late developing showers.