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Basic Recipe

This is the basic recipe for reconstructing HPS data:

1.  EVIO data files are read in and converted to LCIO events.
2. The HPS Java reconstruction is run to add physics object collections to the events.
3. The events are written to an LCIO file containing results of the recon.
4. The recon LCIO file can be converted to ROOT DST Data Format.

Oftentimes, steps 1-3 are performed in the same job (process) for efficiency using the EvioToLcio command line utility.

Overview

The HPS physics reconstruction is implemented in the HPS Java project as a chain of org.lcsim Drivers which process LCIO Data Format events that are accessed using the EventHeader API.  The driver list is described in an lcsim xml steering file which is configured by the lcsim job manager.  

The EVIO Data Format is converted into LCIO by an LCSimEventBuilder such as LCSimEngRunEventBuilder.  The EvioToLcio command line tool reads EvioEvents with an EvioReader and then uses an event builder to create LCIO events representing the raw data.  The driver chain is then run to perform the physics reconstruction which will add additional object collections to the event.  The combined events with the data and recon collections are written out to an LCIO file.  The LCIO output can be converted to ROOT DST Data Format for ROOT compatibility, or it may be loaded back into HPS Java for analysis. 

Basic Recipe

This is the basic recipe for reconstructing HPS data:

1.  EVIO data files are read in and converted to LCIO events.
2. The HPS Java reconstruction is run to add physics object collections to the events.
3. The events are written to an LCIO file containing results of the recon.
4. The recon LCIO file can be converted to ROOT DST Data Format.

Oftentimes, steps 1-3 are performed in the same job (process) for efficiency using the EvioToLcio command line utility.

Reconstruction Drivers 

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.

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