Muon Identification with the ATLAS Tile Calorimeter Read-Out Driver for Level-2 Trigger Purposes

The Hadronic Tile Calorimeter (TileCal) at the ATLAS experiment is a detector made out of iron as passive medium and plastic scintillating tiles as active medium. The light produced by the particles is converted to electrical signals which are digitized in the front-end electronics and sent to the back-end system. The main element of the back-end electronics are the VME 9U Read-Out Driver (ROD) boards, responsible of data management, processing and transmission. A total of 32 ROD boards, placed in the data acquisition chain between Level-1 and Level-2 trigger, are needed to read out the whole calorimeter. They are equipped with fixed-point Digital Signal Processors (DSPs) that apply online algorithms on the incoming raw data. Although the main purpose of TileCal is to measure the energy and direction of the hadronic jets, taking advantage of its projective segmentation soft muons not triggered at Level-1 (with pT<5 GeV) can be recovered. A TileCal standalone muon identification algorithm is presented and its usage at Level-2 can improve the overall ATLAS muon trigger in the low-pT range. Furthermore, the implementation of this algorithm at the ROD DSP level allows fast full scans on the calorimeter to trigger muons at Level-2, fulfilling the latency requirements at this stage. This paper describes the implementation of this muon identification algorithm in the ROD DSPs and its performance on Monte Carlo data as well as the resu lts on real data obtained during detector commissioning with cosmics.