Processing

Data is currently processed within CERN; dedicated virtual machines submit jobs to LSF in several calibration steps before initiating the final pass. The calibration procedure automatically evaluates coarse and fine time alignment of all detectors.

Once the calibration is completed all files pertaining a run are processed and the reconstructed data is stored on CASTOR and EOS. There is a post-processing stage that runs several standard analyzers for a first data quality check, providing reports (pdf files) that are stored next to the directory pertaining the processed run. The classification of the burst quality and the measurement of momentum correction and beam parameters is also being integrated in this stage.

Statistics about the processed data are available here.

Introduction

Data is processed by the NA62Reconstruction package, following the data flow shown here. In order to obtain an output usable for physics a calibration procedure is required. Although the calibration constants are available to the end user, for general use the centrally processed data is the only recommended option. It may still be necessary or convenient for the end user to run NA62Reconstruction, for example on a small MC sample; instructions are available here.

Useful Details

GigaTracker

Currently the reconstruction of tracks in the GigaTracker is available only within NA62Analysis, therefore it is necessary to add GigaTrackerEvtReco to the list of analyzers to run.

Calibration constants

All the calibration constants are currently available only on AFS

/afs/cern.ch/work/n/na62prod/daemonspace/

This is a temporary solution that poses several problems in production, but at the moment it's the only option.

File lists of reconstructed data are available here

/afs/cern.ch/na62/offline/lists/Data/Reco

Postprocessing and Data Quality

As a final step of the data processing, after time alignment and reconstruction, there is a post processing step aimed to provide data quality information and prepare data for exploitation. Here is a description of the process:

  • Basic analyzers collect and re-plot histograms already available in the reconstructed files (currently only MUV3DataQualityMonitor, NewCHODDataQualityMonitor)
  • A scan of EOB data is performed, to prepare for filtering; currently only LAVBurstChecker
  • Filtered data samples are produced, to mitigate I/O performance issues at least for the suitable analyses (currently FilterRestrictedThreeTrackVertex, FilterRestrictedPositron, FilterTwoTrackVertexWithLepton, FilterHNLVertex)
  • Momentum corrections are evaluated using the 2-pass analyzer AlphaBetaComputation, to be used in the following step
  • A set of 2-pass analyzers is used for a more refined data quality monitoring (currently Kmu2Selection K3piSelection DetectorOnOffMonitor NumberOfHitsMonitor MUV3Efficiency RICHElectronRadius RICHMonitor NewCHODEfficiency L0TriggerResponse LevelOnePerformance CedarEfficiency CHANTIMuonEfficiency Ke3Selection LKrEopMonitor LevelOnePerformance).

The results, in the form of ROOT or PDF files, are available on EOS at /eos/experiment/na62/user/n/na62prod/daemonspace/NA62FW<SoftwareVersion>-Run<RunNumber>/RQ and  /eos/experiment/na62/data/offline/data/<Year>/Reco/Run<RunNumber>, while filtered data lists are available at /afs/cern.ch/na62/offline/lists.

For Developers

Postprocessing and Data Quality

As a final step of the data processing, after time alignment and reconstruction, there is a post processing step aimed to provide data quality information and prepare data for exploitation. Here is a description of the process:

  • Basic analyzers collect and re-plot histograms already available in the reconstructed files (currently only MUV3DataQualityMonitor, NewCHODDataQualityMonitor)
  • A scan of EOB data is performed, to prepare for filtering; currently only LAVBurstChecker
  • Filtered data samples are produced, to mitigate I/O performance issues at least for the suitable analyses (currently FilterRestrictedThreeTrackVertex, FilterRestrictedPositron, FilterTwoTrackVertexWithLepton, FilterHNLVertex)
  • Momentum corrections are evaluated using the 2-pass analyzer AlphaBetaComputation, to be used in the following step
  • A set of 2-pass analyzers is used for a more refined data quality monitoring (currently Kmu2Selection K3piSelection DetectorOnOffMonitor NumberOfHitsMonitor MUV3Efficiency RICHElectronRadius RICHMonitor NewCHODEfficiency L0TriggerResponse LevelOnePerformance CedarEfficiency CHANTIMuonEfficiency Ke3Selection LKrEopMonitor LevelOnePerformance). Requirements for such analyzers are described here.

The results, in the form of ROOT or PDF files, are available on EOS at /eos/experiment/na62/user/n/na62prod/daemonspace/NA62FW<SoftwareVersion>-Run<RunNumber>/RQ and  /eos/experiment/na62/data/offline/data/<Year>/Reco/Run<RunNumber>, while filtered data lists are available at /afs/cern.ch/na62/offline/lists.