Analysis TTreeFormat
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Why a standard TTree format?
- For any reaction can streamline (and provide a best-practices implementation of): analysis utilities, BDT setup/input, amplitude analysis setup/input(?)
- Makes it easy for users to keep everything organized, especially handling of the combinatoric background.
- Output can be enabled/disabled with a single flag.
- Format is designed to be one-size-fits-all, but is still extensible (customizable) at every level (see summary).
Summary
- Data Structures:
- DTreeParticle: roughly mirrors DKinematicData: kinematics + PID info of track
- DTreeStep: roughly mirrors DParticleComboStep: collection of DTreeParticle's for a given step of a reaction (e.g. photoproduction, Λ decay, π0 decay, etc.)
- DTreeCombo: roughly mirrors DParticleCombo (collection of DTreeStep's for a given reaction), + detected particles not used in the combo
- DTreeEvent: contains DTreeCombo's for each output DReaction, + thrown tracks
- Extensible:
- Each class has maps to contain additional data (TObject* and double, map keys are string): users can add their own custom information here
- Otherwise they can make a friend TTree to add branches to the existing tree.
- Usage:
- Process with a TSelector.
- TTree::Draw() and TTree::Project will not work due to nested STL containers.
Cons
- Data is contained in deques/maps, which causes problems:
- Impossible to make them split properly for viewing in the TBrowser.
- May (I haven't tested it) make it impossible to use the built-in TTree histogram & cutting options.
DTreeParticle
- Roughly mirrors DKinematicData: kinematics + PID info of track
- p3, v3, and t are stored at both the start (production) and end points (decay, TOF/BCAL/FCAL hit) of the track.
- This is primarily motivated by the Ξ-, which is long-lived and whose trajectory is bent by the magnetic field before it decays.
- Extensible: maps can be used by users to add their own custom information.
class DTreeParticle : public TObject { public: // PID: Particle_t dPID; // KINEMATICS: //If kinematic fit was performed, this is the kinematic fit results. Else is measured results. TVector3 dPosition_Start; //the position where the particle is produced double dTime_Start; //time of the track at dPosition_Start: if value is not kinfit, is projected from measured TOF/BCAL/FCAL time TVector3 dMomentum_Start; //momentum of the track at dPosition_Start TVector3 dPosition_End; //detected particles: the reconstructed position of the BCAL/FCAL/TOF hit; decaying particles: the point where it decays double dTime_End; //time of the track at dPosition_End TVector3 dMomentum_End; //momentum of the track at dPosition_End double dPathLength; //from dPosition_Start to dPosition_End TMatrixDSym dCovarianceMatrix; //at dPosition_Start // Order is (px, py, pz, x, y, z, t) // PID QUALITY: unsigned int dNDF_Tracking; //0 if neutral or decaying double dChiSq_Tracking; //NaN if neutral or decaying unsigned int dNDF_Timing; //0 if no TOF/BCAL/FCAL hit (e.g. slow protons) double dChiSq_Timing; //NaN if no TOF/BCAL/FCAL hit (e.g. slow protons) unsigned int dNDF_DCdEdx; //0 if neutral or decaying double dChiSq_DCdEdx; //NaN if neutral or decaying // DEPOSITED ENERGY: //0.0 if no hit double ddEdx_FDC; double ddEdx_CDC; double dEnergy_BCAL; double dEnergy_FCAL; double dEnergy_TOF; // DTREESTEP POINTERS: DTreeStep* dProductionStep; //the step object in which this DTreeParticle is produced (is a final-state particle) DTreeStep* dDecayStep; //the step object in which this DTreeParticle decays (is an initial-state particle) (will be null if not a decaying particle!) // CUSTOM VARIABLES: map<string, double> dCustomVariables; //key is unique string, double is value map<string, const TObject*> dCustomObjects; //key is unique string, TObject* is object ClassDef(DTreeParticle, 1) };
DTreeStep
- Roughly mirrors DParticleComboStep: collection of DTreeParticle's for a given step of a reaction (e.g. photoproduction, Λ decay, π0 decay, etc.)
- Extensible: maps can be used by users to add their own custom information.
class DTreeStep : public TObject { public: // INITIAL PARTICLES: const DTreeParticle* dInitialParticle; //if is null: decaying or beam particle not yet set! const DTreeParticle* dTargetParticle; //NULL for no target // FINAL PARTICLES: deque<DParticle_t> dFinalParticleIDs; //separate in case particle is NULL (e.g. decaying resonance) deque<const DTreeParticle*> dFinalParticles; //particle may be NULL if it is decaying or missing (especially if no kinematic fit was performed!!) // CUSTOM VARIABLES: map<string, double> dCustomVariables; //key is unique string, double is value map<string, const TObject*> dCustomObjects; //key is unique string, TObject* is object ClassDef(DTreeStep, 1) };
DTreeCombo
- Roughly mirrors DParticleCombo (collection of DTreeStep's for a given reaction), + detected particles not used in the combo
- Extensible: maps can be used by users to add their own custom information.
class DTreeCombo : public TObject { public: // STEPS: deque<const DTreeStep*> dTreeSteps; // RF: bool dRFTimeMatchQuality; //true if good (certain), false if bad (not confident in value (e.g. no "good" tracks have TOF hits)) double dRFTime; double dRFTimeUncertainty; // UNUSED PARTICLES: vector<const DTreeParticle*> dUnusedDetectedParticles; vector<const DTreeShower*> dUnusedDetectedShowers; // KINEMATIC FIT: DKinFitType dKinematicFitType; //Defined in DKinFitResults.h //d_NoFit if not performed double dChiSq_KinematicFit; //NaN if not performed unsigned int dNDF_KinematicFit; //0 if not performed // CUSTOM VARIABLES: map<string, double> dCustomVariables; //key is unique string, double is value map<string, const TObject*> dCustomObjects; //key is unique string, TObject* is object ClassDef(DTreeCombo, 1) };
DTreeEvent
- Contains DTreeCombo's for each output DReaction, + thrown tracks
- Extensible: maps can be used by users to add their own custom information.
class DTreeEvent : public TObject { public: // RUN, EVENT #'s: unsigned int dRunNumber; unsigned int dEventNumber; // DATA: map<string, deque<const DTreeCombo*> > dTreeCombos; //string key is (D)Reaction name, deque is the particle combos deque<const DTreeParticle*> dThrownParticles; // CUSTOM VARIABLES: map<string, double> dCustomVariables; //key is unique string, double is value map<string, const TObject*> dCustomObjects; //key is unique string, TObject* is object ClassDef(DTreeEvent, 1) };
Example: Create & Process Tree
- ROOT doesn't do a good job of properly handling nested STL containers as branches inside of TTree's. Therefore:
- rootcint is used to create a shared object library containing the DTreeEvent, DTreeParticle, etc. objects, which then needs to be loaded prior to processing the TTree.
- Only one branch is created: the one for DTreeEvent.
- TTree::Draw() and TTree::Project() don't work.
Create Tree
- This would be done "under-the-hood" in DANA, but a simple example is shown here: 1 event containing 1 combo, 1 step and 1 particle
void Create_Tree(void) { //load library, create file & tree gSystem->Load("libBANA_ROOT_TREE.so"); TFile* locFile = new TFile("test.root", "RECREATE"); TTree* locTree = new TTree("testtree", "testtree"); //create event: THE ONLY BRANCH ON THE TREE (set run & event #'s) DTreeEvent* locTreeEvent = new DTreeEvent(); locTree->Branch("dTreeEvent", locTreeEvent, 32000, 0); //splitlevel = 0 makes sure no sub-branches are created (ROOT doesn't do them correctly) locTreeEvent->dRunNumber = 12345; locTreeEvent->dEventNumber = 67890; //create a step with one particle in it, set start time DTreeStep* locTreeStep = new DTreeStep(); DTreeParticle* locTreeParticle = new DTreeParticle(); locTreeParticle->dTime_Start = 2.0; locTreeStep->dFinalParticles.push_back(locTreeParticle); //put the step in the combo DTreeCombo* locTreeCombo = new DTreeCombo(); locTreeCombo->dTreeSteps.push_back(locTreeStep); //put the combo in the tree deque<const DTreeCombo*> locCombos; locCombos.push_back(locTreeCombo); string locReactionName = "TestReaction"; locTreeEvent->dTreeCombos[locReactionName] = locCombos; locTree->Fill(); locFile->Write(); locFile->Close(); }
Sample TSelector
Bool_t MySelector::Process(Long64_t entry) { //dTreeEvent IS THE ONLY BRANCH (DTreeEvent*) GetEntry(entry); cout << "run, event #'s: " << dTreeEvent->dRunNumber << ", " << dTreeEvent->dEventNumber << endl; //get the combos for the given reaction string locReactionName = "TestReaction"; deque<const DTreeCombo*> locTreeCombos = dTreeEvent->dTreeCombos[locReactionName]; //grab the step, particle, and start time const DTreeStep* locTreeStep = locTreeCombos[0]->dTreeSteps[0]; const DTreeParticle* locTreeParticle = locTreeStep->dFinalParticles[0]; cout << "t = " << locTreeParticle->dTime_Start << endl; }
Process Tree
void Process_Tree(void) { string locHallDHome = getenv("HALLD_HOME"); string locIncludePath = locHallDHome + string("/include/"); gInterpreter->AddIncludePath(locIncludePath.c_str()); //for particleType.h and whatever else is needed gSystem->Load("libBANA_ROOT_TREE.so"); //load the class definitions so that can read the "dTreeEvent" tree branch TFile* locFile = new TFile("test.root", "READ"); TTree* locTree = (TTree*)locFile->Get("testtree"); locTree->Process("MySelector.C"); //process this TSelector }