KIP-Veröffentlichungen

The Level-1 Calorimeter Trigger (L1Calo) is one of the main trigger systems of the ATLAS detector. Its decision is based on reduced calorimeter granularity and is taken within a short fixed latency of less than 2.5 μs. L1Calo matches digitized calorimeter pulses to the corresponding bunch crossing of the LHC. This is done by two BCID algorithms. These are the PeakFinder algorithm, for non-saturated pulses, and a thresholding SatBCID algorithm, for saturated pulses. During the first long LHC shutdown the L1Calo hardware was upgraded and amongst other improvements the pile-up treatment has been enhanced. In this way the BCID efficiency for small signals was increased, but at the same time a very small inefficiency in the saturated pulses was introduced. The performances for saturated pulses were restored by the introduction of new decision logic in firmware which combines the PeakFinder and the SatBCID algorithms. Furthermore, studies of run-1 data showed that the SatBCID algorithm would not be able to perform efficiently up to the highest energies available in LHC run-2 in which the center of mass energy is increased from 8 to 13 TeV. Therefore a new SatBCID algorithm was introduced based on the upgraded ADCs which provide the digitized data at 80 MHz resulting in doubled pulse resolution. In this thesis both the performance of the new decision logic and of the Sat80 algorithm have been studied using calibration runs.