Speaker
Description
The electromagnetic calorimeter (ECAL) of the CMS detector is homogenous, fine-grained detector made of scintillating lead-tungstate crystals. The CMS ECAL was designed to provide excellent energy resolution for electrons and photons and was crucial in the discovery of the Higgs boson. The good performance of ECAL continues to be important for many CMS physics analyses. The precise alignment of ECAL is necessary to achieve the excellent position resolution required for photon and electron reconstruction and identification in CMS. The position of each ECAL module is determined to an accuracy of 1 mm using photogrammetry measurements in CMS; however, due to the effect of strong magnetic field, this could slightly change. Further alignment of ECAL with respect to the CMS Tracker is performed using dedicated data analysis to ensure correct matching of energy deposits in ECAL with hits in the Tracker. This poster presentation will describe the CMS ECAL alignment procedure, showing alignment results from Run 3 and including efforts to automate the alignment process.
