The TileCal Energy Reconstruction for Collision Data Using the Matched Filter

The Tile Barrel Calorimeter (TileCal) is the central section of the hadronic calorimeter of ATLAS at LHC. It is divided in a central barrel and two extended barrels, where each part is formed by 64 modules in order to complete the entire cylinder. The central barrel modules are divided in 46 cells each, while the extended barrels modules are divided in 14 cells. The energy deposited in each cell is read out by two electronic channels for redundancy and the analog pulse is conditioned by a shaper circuit. Therefore, TileCal comprises more than 10,000 readout channels. The energy is estimated for each channel by reconstructing the amplitude of the digitized pulse sampled every 25 ns. This work presents the performance of an alternative algorithm for TileCal energy reconstruction, namely the TileCal Matched Filter (MF). The performance of the MF method is compared to the currently implemented algorithm (OF2) using collision data acquired in 2010 during LHC operation period. The results showed that the MF presents smaller error estimation (variance) than the OF2 method. In addition to that, the methods showed to be highly correlated with each other for high SNR signals. Preliminary results using a special ATLAS collision data taken later in 2012, for which LHC operated at 25 ns bunch spacing and ATLAS observed an increase of the pile-up effect, are also provided.