Operation of the enhanced ATLAS First Level Calorimeter Trigger at the start of LHC Run-2

In 2015 the LHC is already operating with a higher center-of-mass energy and proton beams luminosity. To keep a high trigger efficiency against an increased event rate, part of ATLAS Level-1 Calorimeter Trigger electronics have been re-designed or newly introduced (Pre-Processors, Merging Modules and Topological Processors). Additionally, to achieve the best possible resolution for the reconstructed physics objects, complex calibration and monitoring systems are employed. Hit rates and energy spectra down to channel level, based on reconstructed events, are supervised with the calorimeter trigger hardware. In this paper the performance of the upgraded Level-1 Calorimeter Trigger at the beginning of LHC Run-2 is illustrated.