Using the Monte Carlo Information
Update on MonteCarloInfo Status

Feb 3, 2004

Motivation:

• Note: The following is really only interesting to people working at the reconstruction or below level. Current Monte Carlo information output to ntuples is more than sufficient for higher level analyses. If you are a user of recon output it is safe to sleep for the next few minutes...
   
• Current Monte Carlo information includes (created in the G4Generator package):
  • McParticle - Basic information about each particle created in the event
    • Particle properties
    • Starting and ending position
    • Starting and ending four momentum
      • Except: gammas have zero four momentum at conversion points
    • etc.
  • McPositionHit - Created for "sensitive" volumes in Tracker (and ACD), one for each McParticle traversing the sensitive volume
    • Entry and exit positions
    • Energy deposited
    • etc.
    • Really designed for the hit digitization algorithms
  • McIntegratingHit - Created for "sensitive" volumes in Calorimeter, except "integrates" over shower particles
    • Similar to above
       
• The current information is more than satisfactory for:
  • The digitization algorithms in order to provide "hits" to feed to the recon algorithms
  • Obtaining global Monte Carlo truth for the event
    • Incident gamma direction
    • Incident gamma energy
    • Type of event
       
• However, current set up insufficient for detailed studies:
  • Detailed interactions in the LAT
    • Example plots of Gammas which Compton scatter before converting
  • Detailed studies of the current pattern recognition
    • Is the pattern recognition finding all the tracks?
    • Is the pattern recognition finding the right tracks?
    • Is the pattern recognition using all the hits?
    • etc.
  • Studying alternate track finding algorithms
    • For example, use MC to train a neural net algorithm
  • Detailed studies of the track fitting
    • Feed fitter tracks from MC and check output track parameters
  • Detailed studies of the vertexing
  • etc.
     
• One could imagine the same sorts of studies for the Calorimeter...
   
• To do more detailed studies requires augmenting the currently available Monte Carlo information.
  • Mostly this involves associating the existing base Monte Carlo information to various levels of the reconstruction (digis, hits/clusters, etc.)
  • Make heavy use of Relational Tables for this

The Pieces:

• Current implementation creates three new classes:
  • McEventStructure
    • Overall description of the event
      • gamma event
      • charged event
      • summarize interactions encountered
      • List of direct daughters which leave McPositionHits (ie hits in tracker/acd)
      • List of "associated" grandchildren (daughters of daughters which also leave hits)
      • etc.
  • McSiLayerHit
    • Ties together McPositionHits with Clusters. A Cluster can be made of several McPositionHits
  • McCandTrack
    • Ties together McSiLayerHits with their association tracks (McParticles)
       
• Lots and Lots of Relational tables
  • McPositionHits to TkrDigis
  • TkrDigis to TkrClusters
  • McPositionHits to TkrClusters
  • McSiLayerHits to MC Tracks
  • MC Tracks to TkrCandidates
  • etc., etc., etc.
     
• Then provide Tools to extract information from the relational tables
  • Relational tables are great for associating information but definitely need tools for getting out what you want...
     
• And a tool (McAnalValsTool) in AnalysisNtuple for putting interesting information into the output ntuple for analysis (this assumed to be done only for people doing detailed studies of recon, it is NOT intended to be part of the "standard" output)

Current Status:

• First implementation (just to get it all working) was "hidden" into TkrRecon
  • Convenient (for me) just to get started
  • Not desirable for general release (or expansion if that is desired)
  • Also had "hidden" above output classes in a TkrRecon private TDS
     
• For more general release:
  • Move code to create new objects and tables, creation and information tools, etc. to a new package: MonteCarloInfo
  • Move new objects into Event/MonteCarlo
  •