ROOT DST Files

Overview

The ROOT DST files are generated from the LCIO output of the reconstruction.  These files can be analyzed using the HpsEvent API in combination with the ROOT data analysis framework. 

The hps-dst project provides the DST Maker used to perform this conversion from LCIO to ROOT and also includes the HpsEvent API implementation.

Software Resources

Here are some useful links related to the DST software.

DST Event Structure

The ROOT based DST's are composed of HpsEvent objects which are used to encapsulate collections (TClonesArray) of physics objects e.g. tracks and particles.  The collections encapsulated by an HpsEvent are shown on Table 1. 

Collection Name (TClonesArray)TypeVariables (ROOT leaves)

References (TRefArray)

tracksSvtTrack # hits, d0, phi, omega, tan_lambda, z0, chi^2 SvtHit
svt_hits SvtHit layer #, corrected position and covariance matrix, hit time  
ecal_clustersEcalCluster # ecal hits, position, energy, hit time, m2, m3 EcalHit, SeedHit
ecal_hits EcalHit position, crystal indices, energy  
fs_particles (Final State Particles) HpsParticle charge, momentum, energy SvtTrack, EcalCluster
uc_vtx_particles (Unconstrained Vertexed Particles) HpsParticle# daughters, charge, fitted momentum, energy, vertex positionHpsParticle
bsc_vtx_particles (Beamspot Vertexed Particles) HpsParticle # daughters, charge, fitted momentum, energy, vertex position HpsParticle
tc_vtx_particles (Target Constrained Vertexed Particles) HpsParticle# daughters, charge, fitted momentum, energy, vertex positionHpsParticle
mc_particles HpsMCParticle pdg id, charge, generator status, energy, mass, momentum, endpoint  
gbl_tracksGblTrackkappa, theta, phi, d0, z0, seed_kappa, seed_theta, seed_phi, seed_d0, seed_z0, chi^2, ndf, momentum, covariance 
gbl_tacks_dataGblTrackData

# of strip hits, kappa, theta, phi, d0, z0

 
gbl_strips_dataGblStripDataid, path3D, path ... 

Table 1: Collections and variables encapsulated by HpsEvent.

The HpsEvent class also contains additional event information, e.g. run number, as shown on Table 2.  

 

ROOT BranchVariables (ROOT leaves)
HpsEventevent #, run #, # tracks, # SVT hits, # Ecal clusters, # Ecal hits, # final state particles, # unconstrained/beam constrained/target constrained particles, # of MC particles, # GBL tracks, # GBL track data, # GBL strips data

Table 2: Variables encapsulated by HpsEvent.

 

 

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