TTM - tpc Track to endcap Tower Matcher

TTM

Author:

Piotr A. Zolnierczuk

Date:

created 2003/12/08

Version:

2.1

Introduction

This a set of MuDST based classes intended to facilitate TPC track to EEMC tower matching. They are also used to calibrate EEMC towers with MIPs and electrons.

The main class is EEmcTTMMaker and there are additional classes as EEmcTower, EEmcTTMatch and EEmcTTDisplay.

Matching algorithm

Here's an outline of the matching algorithm (see also EEmcTTMMaker::Make) is as follows:

1. Events with CTB sum greater than MaxCTBsum (EEmcTTMMaker::SetMaxCTBSum) are rejected.

2. Build a list of good tracks for a given event. The tracks are accepted via EEmcTTMMaker::AcceptTrack:

• use only TPC tracks
• use only primary tracks (type() == primary, see StEvent manual for information)
• flag() > 0 (see StEvent manual for information)
• number of hits per track >= MinTrackHits (EEmcTTMMaker::SetMinTrackHits)
• track length >= MinTrackLength (EEmcTTMMaker::SetMinTrackLength)
• track transverse momentum >= MinTrackPt (EEmcTTMMaker::SetMinTrackPt)
• MinTrackEta <= track pseudorapidity at the origin <= MaxTrackEta (EEmcTTMMaker::SetMinTrackEta and EEmcTTMMaker::SetMaxTrackEta)

3. Loop over all EEMC tower hits with adc value above the pedestal For each tower try to match a track at a set of preselected depths z_1,z_2,... (see EEmcTTMMaker::AddZPosition and EEmcTTMMaker::ResetZPositionsArray):

• extrapolate a track to a depth z_i (i.e. find an intersection r_i of a track with a plane z=z_i) with EEmcTTMatch::ExtrapolateToZ)
• if the distance from the intersection point to the tower center in phi and eta is smaller than a predefined fractions (EEmcTTMMaker::SetDeltaPhiCut and EEmcTTMMaker::SetDeltaEtaCut) of the corresponding tower half-witdh the track is said to match a tower at a depth z_i (EEmcTTMMaker::MatchTrack). To be more explicit:
  • r_i - the intersection point of a track point with a plane z=z_i
  • r_tw - tower center
  • tw_eta - tower half witdth in pseudorapidity
  • tw_phi - tower half witdth in phi
  • f_eta - distance cut in eta (EEmcTTMMaker::SetDeltaEtaCut)
  • f_phi - distance cut in phi (EEmcTTMMaker::SetDeltaPhiCut)
  • track matches a tower at depth z_i if

            (r_i.eta - r_tw.eta) < f_eta*tw_eta AND (r_i.phi - r_tw.phi) < f_phi*tw_phi
    

• a track matches a tower if it matches a tower at each of the predefined depths

4. If a match is found a tower with a list of matched tracks is added to the list of matches, which is accessible with EEmcTTMMaker::GetMatchList.

Parameters

Here is a list of the default values. Each parameter is changeable via corresponding SetXXX method.

Event selection parameters

• CTB sum is no greater than EEmcTTMMaker::kDefMaxCTBsum

Track selection parameters

• track has at least EEmcTTMMaker::kDefMinTrackHits hist
• track is at least EEmcTTMMaker::kDefMinTrackLength cm long
• track pt is at least EEmcTTMMaker::kDefMinTrackPt GeV
• track pseudorapidity at the origin is at least EEmcTTMMaker::kDefMinTrackEta
• track pseudorapidity at the origin is no greater than EEmcTTMMaker::kDefMaxTrackEta

Track matching parameters

• track must be no further than EEmcTTMMaker::kDefDeltaPhiCut x tower phi-half-width from the tower center
• track must be no further than EEmcTTMMaker::kDefDeltaEtaCut x tower eta-half-width the tower center
• tracks are matched at the following depths (cf. StRoot/StEEmcUtil/EEmcGeom/EEmcGeomDefs.h)
  • pres=kEEmcZPRE1+0.1cm
  • post=kEEmcZPOST-0.1cm
  • smd=kEEmcZSMD

Matching Results

EEmcTTMMaker main "product" is a list of EEmcTTMatch'es which in turn is a EEmcTower object plus a list of StMuTrack's that fullfill the above mentioned criteria. One can also ask EEmcTTMMaker to produce a nanodst ROOT file (ndst.root) with a ttm tree which contains four branches:

• matches - list of matches
• info - a copy of StEventInfo from muDST
• summary - a copy of StEventSummary from muDST
• trigger - a copy of StMuTriggerIdCollection from muDST

See also macro readnanodst.C for in Section Reading Nano DST file for an example how to read nanodst.

Here are some examples of matched tracks (from Run2003)

Screen Shot

Multi-track event

Example

Using EEmcTTMMaker

// example macro to use  EEmcTTMMaker
// Author: Piotr A. Zolnierczuk, IUCF
// Date: 05/04/2004
// 

// ROOT/ROOT4STAR 
class StChain;
class StMuTrack;
class StMuDstMaker;
class StEventInfo;
// TTM STUFF
class EEmcTower;
class EEmcTTMatch;
class EEmcTTMMaker;

StChain       *chain=0;
EEmcTTMMaker  *ttm  =0;
StMuDstMaker  *muDstMaker= 0;

void
ttmexample
(
 char*  inpDir    = "",             // MuDST directory
 char*  inpFile   = "ttm.lis",      // MuDST file(s);                      
 char*  outFile   = "ttm.ndst.root",// output nano dst root file
 Int_t  nFiles    = 150,            // # of MuDST file(s)
 Int_t  nEvents   = -1              // # of events
 )
  // NOTES: 
  // 1. EEmcTTMMaker main "product" is a list of EEmcTTMatch'es which in turn are 
  //    EEmcTower plus a list of StMuTrack's that fullfill certain criteria. 
  // 2. Optionally the Maker created a nanoDst file [ or a 'Not-a-Dst' file :) ]
  // 
{ 
  // load root/root4star libraries
  gROOT->LoadMacro("$STAR/StRoot/StMuDSTMaker/COMMON/macros/loadSharedLibraries.C");
  loadSharedLibraries();
  // load more libraries :)
  gSystem->Load("libmysqlclient");
  gSystem->Load("StDbLib");
  gSystem->Load("StDbBroker");
  gSystem->Load("St_db_Maker");
  // load even more libraries (EEMC stuff) 
  gSystem->Load("StEEmcUtil");
  gSystem->Load("StEEmcDbMaker");
  gSystem->Load("StEEmcPoolTTM");

  // create the chain    
  chain = new StChain("StChain"); 
  
  // now we add Makers to the chain...  some of that is black magic to me :) 
  muDstMaker = new StMuDstMaker(0,0,inpDir,inpFile,"",nFiles);  // muDST main chain
  StMuDbReader  *db          = StMuDbReader::instance();        // need the database
  StEEmcDbMaker *eemcDbMaker = new StEEmcDbMaker("eemcDb");     // need EEMC database  
  St_db_Maker   *dbMk        = new St_db_Maker("StarDb", "MySQL:StarDb"); // need more db?

  // now comment in/out/change the below if you want it your way
  eemcDbMaker->setSectors(1,12);           // request sectors you need (default:1-12)
  eemcDbMaker->setPreferedFlavor("onlped","eemcPMTped"); // request alternative db flavor 

  // finally after so many lines we arrive at the good stuff
  ttm = new  EEmcTTMMaker ("TTM",muDstMaker,eemcDbMaker);
  ttm->SetFileName(outFile); // output nanoDst file
  // have cuts your way (optional)
  ttm->SetMaxCTBSum(1000); 
  ttm->SetMinTrackLength(20.0);
  ttm->SetMinTrackHits(5);
  ttm->SetMinTrackPt(0.5);
  ttm->SetMinTrackEta(0.7);
  ttm->SetMaxTrackEta(2.2);
  ttm->SetDeltaEtaCut(0.7); // ! note this is a fraction of tower width in eta
  ttm->SetDeltaPhiCut(0.7); // ! note this is a fraction of tower width in phi
  // this is even more optional :)
  // the lines here repeat the default
  // ttm->ResetZPositionsArray();
  // ttm->AddZPosition("pres",kEEmcZPRE1+0.1);
  // ttm->AddZPosition("post",kEEmcZPOST-0.1);
  // ttm->AddZPosition("smd" ,kEEmcZSMD);
  ttm->Summary(cout);       // prints cut summary

  StMuDebug::setLevel(0);
  chain->Init();
  chain->ls(3);

  //---------------------------------------------------
  int  stat=0;
  int  event=0;
  while(++event<nEvents) {
    stat=chain->Make();
    // STAR intelligence: stat=2 EOF,stat=4 FATAL; if so break the loop
    // if not OK (and not EOF nor FATAL) !!! try another event
    if( stat==2 || stat==4) break;
    if( stat!=0           ) continue;

    // if no track to tower matches try another event
    if(ttm->GetMatchList()->IsEmpty()) continue;

    // set up iterator and pointers
    TIter  nextMatch(ttm->GetMatchList());
    EEmcTTMatch *tmatch;
    EEmcTower   *tower;
    StMuTrack   *track;
    //event info (for fun), it shows we like xml
    StEventInfo    &evInfo = muDstMaker->muDst()->event()->eventInfo();   
    cerr << "<Event";
    cerr << "Run=\""  << evInfo.runId() << "\"\t";
    cerr << "Event=\""<< evInfo.id()    << "\">\n";
    // loop over all towers with track hits
    while ((tmatch = (EEmcTTMatch*) nextMatch())) {
      tmatch->Out(cerr); // prints all match info
      tower = tmatch->Tower();
      // here's how to acces tower information
      const char *tLabel = tower->TowerLabel();
      int sector = tower->Sec();    // 0..11
      int subsec = tower->SubSec(); // 0..4
      int etabin = tower->Eta();    // 0..11
      float adc  = tower->ADC();    // adc - pedestal
      float de   = tower->dE();     // (adc - pedestal)/gain
      //
      int seclab = tower->SecLabel();    // 1..12
      int sublab = tower->SubSecLabel(); // A..E
      int etalab = tower->EtaLabel();    // 1..12
      // now more than one track may hit a tower
      TIter nextTrack(tmatch->Tracks());
      while((track=(StMuTrack *)nextTrack()))  {
        // how to access StMuTrack consult muDST manual (does not exist)
        TVector3 r;
        // for example one could extrapolate track to a given z-depth
        EEmcTTMatch::ExtrapolateToZ(track,290.0,r);
        double pt = track->pt();
        double x  = r.x();
      }
    }
    cerr << "</Event>" << endl;
  }
  ttm->Summary(cerr);
}

Reading Nano DST file

void 
loadlibs()
{
  gROOT->LoadMacro("$STAR/StRoot/StMuDSTMaker/COMMON/macros/loadSharedLibraries.C");
  loadSharedLibraries();
  // load more libraries :)
  gSystem->Load("libmysqlclient");
  gSystem->Load("StEvent");
  gSystem->Load("StDbLib");
  gSystem->Load("StDbBroker");
  gSystem->Load("St_db_Maker");
  // load even more libraries (EEMC stuff) 
  gSystem->Load("StEEmcUtil");
  gSystem->Load("StEEmcDbMaker");
  gSystem->Load("StEEmcPoolTTM");
}


void 
readndst(const char *fName="/star/current/ndst/run*.ndst.root")
{
  loadlibs();
  TChain *chain = new TChain("ttm");
  chain->Add(fName);
  Double_t nev = chain->GetEntries();

  cerr << nev << endl;

  TList          *matchlist       = new TList;                  
  StEventInfo    *evinfo          = new StEventInfo();
  StEventSummary *evsumm          = new StEventSummary();
  StMuTriggerIdCollection *evtrig = new StMuTriggerIdCollection();

  chain->SetBranchAddress("matches",&matchlist);
  chain->SetBranchAddress("info"   ,&evinfo);
  chain->SetBranchAddress("summary",&evsumm);
  chain->SetBranchAddress("trigger",&evtrig);

  for(int i=0; i<nev; i++) {
    EEmcTTMatch *tmatch;
    chain->GetEntry(i);
    if(matchlist->IsEmpty()) continue;
    StTriggerId &trig = evtrig->nominal();
    cerr << "<Event id=\""        << evinfo->id() << "\" run=\" " << evinfo->runId() << "\" >\n";
    cerr << "<MagneticField b=\"" << evsumm->magneticField() << "\" >\n";
    TIter nextMatch(matchlist);
    while ((tmatch = (EEmcTTMatch *) nextMatch())) 
      tmatch->Out(cerr);
    cerr << "</Event>\n" << endl;
  }
} 

Remarks

Todo:

write additional makers that would produce electron and MIP calibrations

more documentation?

---