Construction of the first CMS-ECAL fully operational module (400 lead tungstate crystals)

The CMS Electromagnetic Calorimeter (ECAL) will be made of almost 80000 lead tungstate crystals. The barrel part will be composed of 36 supermodules with 1700 crystals each, divided in 4 modules. This paper reports on the construction of the first module, called Mod #0', that will be tested under beam conditions. The optimum quality of the crystals that form Mod #0' together with the light collection uniformization techniques applied and the results obtained will be described. In addition, different gluing techniques and results for the 400 Mod #0' crystals will be also reported. Other aspects, such as the mounting sequence that follows the gluing of the crystals to the photodetectors or the thermal regulation of the module will be also discussed. (7 refs).