StGenericVertexMaker/StCtbMatcher.h

#ifndef ST_CTB_MATCHER_H
#define ST_CTB_MATCHER_H

#include <vector>
#include "StEvent/StTrack.h"
#include "StarClassLibrary/StPhysicalHelixD.hh"
#include "StarClassLibrary/StThreeVectorD.hh"
#include "TMath.h"
struct ctbHit{
    double phi;
    double eta;
    float adc;
};


unsigned int EtaAndPhiToOrriginAtCTB(StTrack* rTrack, // Pointer to Track
                                     vector<ctbHit>* ctbHits,
                                     bool & shouldHit,
                                     double & trackEtaInCTBFrame){
        
    const double Rctb=213.6; // (cm) radius of the CTB

    // Set Minimum pt to look at
    if(rTrack->geometry()->momentum().perp() < .20)
        return false;

    StPhysicalHelixD theHelix = rTrack->geometry()->helix();
    pairD pathLength = theHelix.pathLength(Rctb);
    
    if(pathLength.second < 0){
        cout << "pathLength is bad" << endl;
        return false;
    }
    
    StThreeVectorD pos = theHelix.at(pathLength.second);
    
    double phi = atan2(pos.y(),pos.x())*180/TMath::Pi();
    if(phi < 0)
        phi+= 360;
    
    double theta = atan2(pos.perp(),pos.z());
    double eta = -::log(tan(theta/2.0));
    trackEtaInCTBFrame = eta;
    
    // if |eta| < 1 then track should have hit the CTB.
    if(fabs(eta) < 1)
        shouldHit = true;
    else
        shouldHit = false;

    // Loop over CTB Hits To see if a match
    float deta,dphi;
    for(unsigned int i = 0; i < ctbHits->size() ; i++){
        ctbHit curHit = (*ctbHits)[i];
        deta = fabs(curHit.eta - eta);
        if(curHit.phi != 0){
            dphi = fabs(curHit.phi - phi);
            if( dphi < 3 && deta < .25){
                return static_cast<unsigned int>(curHit.adc);
            }
        }
        else{
            if( (phi < 3 || phi > 357) && deta < .25){
                return static_cast<unsigned int>(curHit.adc);
            }
        }
    }
    // cout << endl;
    // Else return 0
    return 0;
}
   
void  ctb_get_slat_from_data(int slat, int tray, double & ctbphi, double & ctbeta) {
    // Function copied verbatum from St_dst_Maker/CtbResponce. We may want to clean this up.
    
    float phiZero1 = 72 ; // magic lines from Pablo & Herb
    float phiZero2 = 108 ;
    float deltaPhi = 6 ;
    // tray=0,1
    // slat=0,...,119
    
    int iz ;        
    double phi,eta ;
    
    if ( tray < 60 )  {
        phi = phiZero1 - tray * deltaPhi ; 
        iz = 0 ;
  }  else {
      phi = phiZero2 + (tray-60) * deltaPhi ;
      iz = 1 ;
  }

    if ( phi <   0. ) phi += 360 ;
    if ( phi > 360. ) phi -= 360 ;
    
    ctbphi=phi;
    eta = (1-2*iz)*(1+2*slat)*0.25;
    ctbeta =(1-2*iz)*(1+2*slat)*0.25;
    
    //printf("CTB hit: slat=%d, tray=%d,  phiDeg=%f/deg, eta=%f\n",slat,tray,ctbphi,ctbeta);
        
} 

#endif

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