Time Reconstruction and Performance of the CMS Electromagnetic Calorimeter

Understand

The resolution and the linearity of time measurements made with the CMS electromagnetic calorimeter are studied with samples of data from test beam electrons, cosmic rays, and beam-produced muons.

• The resulting time resolution measured by lead tungstate crystals is better than 100 ps for energy deposits larger than 10 GeV.
• Crystal-to-crystal synchronization with a precision of 500 ps is performed using muons produced with the first LHC beams in 2008.