Thermal analysis for eta=3 region of CMS ECAL endcap and preshower

The Electromagnetic Calorimeter (ECAL), a subdetector of the CMS experiment, has to achieve very tight requirements in terms of temperature stability. The temperature variation over time in an SC array should be less than +/-0.1 K. The heat source in the ETA=3 region is the nitrogen circulating in the area, whose temperature can fluctuate by up to 3 K from its mean. The goal of this analysis is to find what will be the temperature variation inside a SC array caused by nitrogen temperature fluctuations and to compare it with the required values. Conclusions and suggestions will be also drawn.