Manoj Kumar Jha INFN – Bologna On Behalf of ATLAS Muon Calibration Group 20 th October 2010/CHEP 2010, Taipei ATLAS Muon Calibration Framework

Outline 20/10/2010 Manoj Kumar Jha (INFN – Bologna) 2 ATLAS muon spectrometer MDT drift tube chambers Resolution requirements Calibration strategy stream processing Latency

ATLAS Muon Spectrometer Standalone Muon Spectrometry ∆p T / p T < 10% up to 1 TeV Coverage | η | < 2.7 (| θ | < 86 0 ) Layout Superconducting air coil toroid Trigger chambers: RPC (Barrel) and TGC (end-cap) Precision chambers: MDT, CSC (inner end-cap) Muon Stations 20/10/ Manoj Kumar Jha (INFN – Bologna)

MDT Drift Tube Chambers Drift Tube Ar/CO 2 3 bar absolute Ø Tube = 30 mm and Ø Wire = 50 μ m High Voltage = 3080 Gas gain = 2.0 x Resolution = 80 μ m MDT Chambers 2 multi-layers with 3 or 4 layers Surface 0.5 to 11 m 2 Monitoring of geometry, temperature and magnetic field. 20/10/ Manoj Kumar Jha (INFN – Bologna)

Resolution Requirements First Collisions p T < 100 GeV: Resolution dominated by multiple scattering and energy loss Required rt –precision: O(100 μ m) Design Parameters p T > 100 GeV: Resolution dominated by spatial resolution. Required rt –precision: O(20 μ m) 20/10/ Manoj Kumar Jha (INFN – Bologna)

Calibration Strategy t0 determination Starting point of drift time spectrum Needed for equalization of time measurement of all the drift tubes ~10K hits per tube are needed Integration of drift time integration Gives start rt with precision O(100 μ m) Auto calibration Fit segments using input rt Deviation of r drift from r segment gives correction Iterate Resolution Fit segment omitting one tube σ (residual) = σ residual ⊕ σ drift Iterate Required precision 20 μ m to be done within 24 hrs after data taking. 20/10/ Manoj Kumar Jha (INFN – Bologna)

Correction Functions One rt relation is fitted by chamber. To compensate for effects, which are inhomogeneous inside one chamber, rt correction functions are applied Wire-sag Barrel: Bend tubes so that the wire is always in middle End-cap: Apply rt-correction Temperature Magnetic field 20/10/ Manoj Kumar Jha (INFN – Bologna)

Calibration Stream Muon trigger RPC-chambers muon trigger level 1 momentum from mdt-chambers muon trigger level 2 event filter level-3 trigger Calibration centers outside CERN (tier-2 subclusters) Michigan Munich (MPI+LMU) Roma & Napels calibration stream ~100 kHz ~1 kHz ~100 Hz 1/3 μ 20/10/ Manoj Kumar Jha (INFN – Bologna)

Calibration Processing: Data Flow Calibration datasets from ATLAS Tier0 are sent to remote calibration center using distributed data management system. Calibration Farms at remote center process the files as soon as they are available in local storage element. 20/10/ Manoj Kumar Jha (INFN – Bologna)

Calibration Processing: Calibration center Calibration centers are established at ATLAS Tier2 with additional job and data management components to control the calibration task Dynamic partitioning of computing resources Reservation of storage resources Job management Entry point for grid jobs which needs a digital certificate to operate and are integrated in Batch Queue Manager. Recently, job submission tool Ganga has been integrated for job management and bookkeeping Tasks can be submitted to different backend like Panda and LCG Tasks can be splitted on basis of number of files, events and subjobs. Better management of task output. For more information on Ganga, see talk by Johannes Elmeshuer. 20/10/ Manoj Kumar Jha (INFN – Bologna)

Calibration Processing: Architecture Local Calibration Data Splitter (LCDS) permanently watches for incoming data. As soon as the first data arrive in local storage element, LCDS starts submitting a set of jobs to calibration batch queue. Monitoring of calibration task is performed by monitoring client integrated in LCDS. Relevant data gets store at the end of calibration task and data could be in principle released and marked for deletion from Tier2 storage. 20/10/ Manoj Kumar Jha (INFN – Bologna)

Latency  Calibration tasks were submitted using job submission tool Ganga.  Number of subjobs corresponding to a dataset depends upon number of files in the dataset.  Latency is peaked at around 2 hrs.  Most of the datasets are processed in the calibration centers after 2 hrs of data taking. 20/10/ Manoj Kumar Jha (INFN – Bologna)

Summary Ganga as job submission tool has been integrated into LCDS. Remote center used for calibration of MDT chambers have been setup and their functionalities have been tested with real data. Latency is peaked around 2 hrs. ATLAS muon calibration framework can be extended for calibration to other sub system of detector. 20/10/ Manoj Kumar Jha (INFN – Bologna)