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The HPS physics reconstruction is implemented within the HPS Java project as a chain of of org.lcsim Drivers (event processors) which process LCIO Data Format events that are accessed through the EventHeader API. The Drivers are described by an lcsim xml steering file, which is read described by lcsim xml and run by the lcsim job manager. Detector Conditions including per channel calibrations are read and applied in the initialization phase. The data from each event is processed to produce additional output collections containing reconstructed objects such as tracks and calorimeter clusters. First, the raw data must be converted from EVIO Data Format using an LCSimEventBuilder such as LCSimEngRunEventBuilder. The EvioToLcio command line tool is used to read EvioEvents with an EvioReader and then uses the event builder to create LCIO raw data events. The full Driver chain is run on the raw data collections to perform the physics reconstruction. These combined The EvioToLcio command line tool is used to convert the EVIO to LCIO events using an LCSimEventBuilder such as LCSimEngRunEventBuilder. The LCIO events are accessed in Java code through the EventHeader API. The Drivers add output collections to the event such as tracks, calorimeter clusters, reconstructed particles and vertices. The combined data/physics LCIO events are written out to an LCIO file, which can subsequently be converted to ROOT DST Data Format. The LCIO events may also be loaded back into the HPS Java environment for analysis.
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This is the basic recipe for reconstructing HPS data:
These are the steps performed in reconstructing the data:
Steps 1-3 6 are typically performed in the same job (process) using the EvioToLcio command line utility.
User analysis can be performed on the LCIO files using the job manager command line tool or within the ROOT environment using the DSTs.
The reconstruction Driver chain is defined in production steering files such as EngineeringRun2015FullRecon.lcsim, which are kept in this SVN folder and typically accessed as a class resource from a jar file.
Order | Driver Name | Driver Class | Description | |||
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1 | RfFitter | RfFitterDriver | converts accelerator's RF wave form to time and inserts into event | |||
2 | EcalRunningPedestal | calculates per channel running averages for ECal signal pedestals | ||||
3 | EcalRawConverter | EcalRawConverterDriver | converts ECal digits to CalorimeterHit collection with energy and time measurements | |||
4 | ReconClusterer | ReconClusterDriver | performs calorimeter clustering algorithm on ECal hits | |||
5 | CopyCollection | CopyClusterCollectionDriver | copies calorimeter clusters to new collection to preserve uncorrected energy measurements | |||
6 | RawTrackerHitSensorSetup | RawTrackerHitSensorSetup | assigns RawTrackerHits to their sensors for use by track recon | |||
7 | RawTrackerHitFitterDriver | RawTrackerHitFitterDriver | fits ADC vs time signal to produce fitted hits collectionand stores the results, associated to each raw hit | |||
8 | TrackerHitDriver | DataTrackerHitDriver | creates stereo pairs from from SVT strip hits | |||
9 | HelicalTrackHitDriver | HelicalTrackHitDriver | creates 3D hits hit clusters from clusters of stereo pairs | |||
10 | TrackReconSeed345Conf2Extd16 | TrackerReconDriver | runs track finding using layers 3, 4 & 5 as a seed, layer 2 to confirm, and layers 1 and 6 to extend | |||
11 | TrackReconSeed456Conf3Extd21 | TrackerReconDriver | runs track finding using layers 4, 5 & 6 as a seed, layer 3 to confirm, and layers 2 and 1 to extend | |||
12 | TrackReconSeed123Conf4Extd56 | TrackerReconDriver | runs track finding using layers 1, 2 & 3 as a seed, layer 4 to confirm, and layers 5 and 6 to extend | |||
13 | TrackReconSeed123Conf5Extd46 | TrackerReconDriver | runs track finding using layers 1, 2 & 3 as a seed, layer 5 to confirm, and layers 4 and 6 to extend | |||
14 | MergeTrackCollections | MergeTrackCollections | merge merges collections from track finding into a single output collection | |||
15 | GBLRefitterDriver | GBLRefitterDriver | performs GBL track refit | |||
16 | TrackDataDriver | TrackDataDriver | adds additional collections containing track information to the output event | |||
17 | ReconParticleDriver | HpsReconParticleDriver | creates output reconstructed particle collectioncollections, associating tracks with clusters also performs vertex reconstruction and creates vertex collection | |||
18 | LCIOWriter | LCIODriver | writes output LCIO file | |||
19 | CleanupDriver | ReadoutCleanupDriver | cleanup cleans up readout state for next event (clears assignments of SVT raw hits to sensors) | AidaSaveDriver | AidaSaveDriver | saves AIDA plots to file at end of job
Collection | Java Class | Created By | Description |
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BeamspotConstrainedMollerCandidates | ReconstructedParticle | HpsReconParticleDriver | Møller candidate particles required to point back to beamspot at the target |
BeamspotConstrainedMollerVertices | Vertex | HpsReconParticleDriver | Møller vertices required to point back to beamspot at the target |
BeamspotConstraintedV0Candidates | ReconstructedParticle | HpsReconParticleDriver | electron-positron candidate particles required to point back to beamspot at the target |
BeamspotConstraintedV0Vertices | Vertex | HpsReconParticleDriver | electron-positron vertices required to point back to beamspot at the target |
EcalCalHits | CalorimeterHit | EcalRawConverterDriver | calibrated ECal Hits |
EcalClusters | Cluster | ReconClusterDriver | reconstructed ECal clusters with uncorrected energies |
EcalClustersCorr | Cluster | CopyClusterCollectionDriver | reconstructed ECal clusters with corrected energies
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EcalReadoutHits | RawTrackerHit | EcalEvioReader | ECal Hits in ADC counts |
EpicsData | GenericObject | LCSimEngRunEventBuilder | EPICS data banks |
FADCGenericHits | GenericObject | EcalEvioReader | additional FADC readout information |
FinalStateParticles | ReconstructedParticle | HpsReconParticleDriver | final state particles (electrons, positrons, photons) with 4-momenta |
GBLKinkData | GenericObject | GBLRefitterDriver | extra GBL track kink data |
GBLKinkDataRelations | LCRelation | GBLRefitterDriver | relation from GBLTracks to GBLKinkData |
GBLTracks | Track | GBLRefitterDriver | tracks created from GBL refit |
HelicalTrackHitRelations | LCRelation | HelicalTrackHitDriver | relation from HelicalTrackHits to StripClusterer_SiTrackerHitStrip1D |
HelicalTrackHits | TrackerHit | HelicalTrackHitDriver | 3D hits combining StripClusterer_SiTrackerHitStrip1D hits in axial/stereo layers |
MatchedToGBLTrackRelations | LCRelation | GBLRefitterDriver | relation from MatchedTracks to GBLTracks |
MatchedTracks | Track | TrackerReconDriver | primary collection of reconstructed tracks merged from collections with tracks generated from different strategies |
PartialTracks | Track | MergeTrackCollections | collection of tracks which have a set of hits that are a strict subset of another track |
RotatedHelicalTrackHitRelations | LCRelation | HelicalTrackHitDriver | relation from RotatedHelicalTrackHit to HelicalTrackHit |
RotatedHelicalTrackHits | TrackerHit | HelicalTrackHitDriver | HelicalTrackHits rotated into SeedTracker tracking frame: x→y, y→z, z→x |
SVTFittedRawTrackerHits | LCRelation | RawTrackerHitFitterDriver | relation from SVTRawTrackerHits to SVTShapeFitParameters |
SVTRawTrackerHits | RawTrackerHit | SvtEvioReader | Si sensor single strip hits |
SVTShapeFitParameters | GenericObject | RawTrackerHitFitterDriver | results of the ADC vs sample number fits for SVT data |
StripClusterer_SiTrackerHitStrip1D | TrackerHit | DataTrackerHitDriver | 1D Si strip clusters |
TargetConstrainedMollerCandidates | ReconstructedParticle | HpsReconParticleDriver | Møller candidate particles with the vertex z fixed to the target position and (x,y) constrained to beamspot |
TargetConstrainedMollerVertices | Vertex | HpsReconParticleDriver | Møller vertices with the vertex z fixed to the target position and (x,y) constrained to beamspot |
TargetConstrainedV0Candidates | ReconstructedParticle | HpsReconParticleDriver | electron-positron pairs with the vertex z fixed to the target position and (x,y) constrained to beamspot |
TargetConstrainedV0Vertices | Vertex | HpsReconParticleDriver | electron-positron vertices with the vertex z fixed to the target position and (x,y) constrained to beamspot |
TrackData | GenericObject | TrackDataDriver | additional track information |
TrackDataRelations | LCRelation | TrackDataDriver | relation from TrackData to a Track |
TrackResiduals | GenericObject | TrackDataDriver | X & Y track residuals calculated at the stereo hit position |
TrackResidualsRelations | LCRelation | TrackDataDriver | relation from TrackResiduals to a Track |
TriggerBank | GenericObject | LCSimEngRunEventBuilder | trigger information for the event |
UnconstrainedMollerCandidates | ReconstructedParticle | HpsReconParticleDriver | Møller particle candidates with unconstrained vertex |
UnconstrainedMollerVertices | Vertex | HpsReconParticleDriver | unconstrained Møller vertices |
UnconstrainedV0Candidates | ReconstructedParticle | HpsReconParticleDriver | electron-positron pairs with unconstrained vertex |
UnconstrainedV0Vertices | Vertex | HpsReconParticleDriver | unconstrained electron-positron vertices |
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These are the primary steps involved in the HPS Java track reconstruction:
The tracking packages in lcsim form the basis for HPS's tracking algorithms through usage and extension. Seed Seed Tracker is used for track finding using a set of input tracking strategies. The
The track fit from lcsim is further refined using a Java implementation (port) of the GBL C++ algorithm.
Each track has a TrackType assigned which indicates the SeedTracker algorithm used, in a bitwise fashion, and sets bit 6 (2^5=32) if the track was refined by GBL. The TrackType is inherited by any particle and is obtained with the getType() method. See: TrackType and StrategyType for details.
This paper describes the LCIO track parameters.
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HPS Java Reconstruction Packages
The The HPS Java Documentation can be used to browse the packages and classes used for physics reconstruction.
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Java Package | Description | Notes |
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org.lcsim.event | physics event interfaces (implemented by LCIO) | interfaces used extensively in HPS Java Drivers |
org.lcsim.util.loop | event processing loop | extends Freehep loop classes for lcsim usage |
org.lcsim.job | lcsim job manager which reads lcsim xml steering files | |
org.lcsim.lcio | Java implementation of LCIO file format | implements event interfaces |
org.lcsim.recon.tracking.seedtracker | Seed Tracker track reconstruction algorithm | basis for HPS Java tracking algorithm |
org.lcsim.util | Driver class for event data processing | |
org.lcsim.conditions | detector conditions system backend | |
org.lcsim.geometry, org.lcsim.detector | detector description and geometry classes |