The Standard Analyzer

This document refers to version 1.0 or higher of the C++ analyzer.

The "standard analyzer" provides a generic event loop and analysis chain that will, hopefully, be sufficient for most physics analysis purposes. The event loop and high-level algorithm are implemented in the method THaAnalyzer::Process() of the class THaAnalyzer. The standard spectrometer processing algorithm is implemented in the method THaSpectrometer::Reconstruct() of the class THaSpectrometer.

THaAnalyzer::Process( THaRun& run ) carries out the following functions:

• Open the CODA input file associated with the run using THaRun::OpenFile().

• Open the ROOT output file if not already open. If the file is already open, but the filename has changed, close the old file and open a new one.

• If no "Event" object has been set by the user, use THaEvent by default. This event contains standard bookkeeping information such as run and event number, event time stamp, beam helicity, etc.

• Reset() the Event object.

• Loop over all events in the CODA file.

• Skip events until the a prestart event is found. Extract the time stamp of the prestart event and call Init( time_stamp ) for every THaApparatus object defined in the gHaApps list, every THaPhysicsModule object defined in the gHaPhysics list, and every THaScaler object defined in the gHaScalers list.

• After initializing the modules (and thus setting up their global variables), load the tests defined in the definition file (SetCutFile()).

• After loading the tests, load the output definitions (THaOutput::Init()) from the output definition file (SetOdefFile()). This sets up a TTree in the output file..

• After finding the prestart event and initializing the apparatuses and scalers, only analyze events in the event range of the run. Distinguish between physics events and scaler events. For physics events, do
  • For each apparatus defined in gHaApps, call THaApparatus::Decode().
  • For each apparatus, call CoarseReconstruct(). If the apparatus does not implement CoarseReconstruct(), this call does nothing.
  • For each apparatus, call Reconstruct().
  • For each defined physics module, call Process().
  • If an Event structure has been defined, call its Fill() method (derived from THaEvent::Fill()).
  • Fill the output tree and histograms by calling THaOutput::Process().

  For scaler events, do

  • For each THaScaler object defined in gHaScalers, call THaScaler::LoadData().

• Close the CODA input file.

• Write() the ROOT output file.

• Loop over all THaTrackingDetectors and call their CoarseTrack() methods.

• Loop over all THaNonTrackingDetectors and call their CoarseProcess() methods.

• Loop over all THaTrackingDetectors and call their FineTrack() methods.

• Loop over all THaNonTrackingDetectors and call their FineProcess() methods.

• Call TrackCalc(). This method usually calculates overall track properties such as the absolute momentum and beta and may also be used to identify the "Golden Track".

• Call FindVertices(). This method usually reconstructs tracks to the target.

Maintained by Ole Hansen