PWG2/FLOW/AliFlowLYZEventPlane.cxx

   1 /*************************************************************************
   2 * Copyright(c) 1998-2008, ALICE Experiment at CERN, All rights reserved. *
   3 *                                                                        *
   4 * Author: The ALICE Off-line Project.                                    *
   5 * Contributors are mentioned in the code where appropriate.              *
   6 *                                                                        *
   7 * Permission to use, copy, modify and distribute this software and its   *
   8 * documentation strictly for non-commercial purposes is hereby granted   *
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  10 * copies and that both the copyright notice and this permission notice   *
  11 * appear in the supporting documentation. The authors make no claims     *
  12 * about the suitability of this software for any purpose. It is          *
  13 * provided "as is" without express or implied warranty.                  *
  14 **************************************************************************/
  15
  16 #define AliFlowAnalysisWithLYZEventPlane_cxx
  17
  18 // AliFlowLYZEventPlane:
  19 //
  20 // Class to calculate the event plane and event weight from the LYZ method
  21 // It needs input from the standard LYZ first and second run
  22 // author: N. van der Kolk (kolk@nikhef.nl)
  23
  24 #include "Riostream.h"
  25 #include "TProfile.h"
  26 #include "TFile.h"
  27 #include "TComplex.h"
  28
  29 #include "AliFlowVector.h"
  30 #include "AliFlowLYZConstants.h"
  31 #include "AliFlowEventSimple.h"
  32 #include "AliFlowLYZEventPlane.h"
  33
  34 class AliFlowTrackSimple;
  35
  36 ClassImp(AliFlowLYZEventPlane)
  37
  38   //-----------------------------------------------------------------------
  39
  40 AliFlowLYZEventPlane::AliFlowLYZEventPlane():
  41   fSecondRunFile(0),
  42   fSecondRunFileName("noname.ESD"),
  43   fWR(0),
  44   fPsi(0),
  45   fSecondReDtheta(0),
  46   fSecondImDtheta(0),
  47   fFirstr0theta(0)
  48 {
  49   // Constructor.
  50
  51 }
  52 //-----------------------------------------------------------------------
  53
  54
  55 AliFlowLYZEventPlane::~AliFlowLYZEventPlane()
  56 {
  57   //destructor
  58
  59 }
  60
  61
  62 //-----------------------------------------------------------------------
  63 void AliFlowLYZEventPlane::Init()
  64 {
  65   //Declare histograms & get input files
  66   cout<<"---Lee Yang Zeros Event Plane Method---"<<endl;
  67
  68   //input histograms
  69   if (fSecondRunFile->IsZombie()){ //check if file exists
  70     cout << "Error opening file, run first regular LYZ second run" << endl;
  71     exit(-1);
  72   } else if (fSecondRunFile->IsOpen()){
  73     cout<<"----secondRunFile is open----"<<endl;
  74     //get List
  75     TList* list = (TList*)fSecondRunFile->Get("cobj1");
  76     fSecondReDtheta = ( TProfile*)list->FindObject("Second_FlowPro_ReDtheta_LYZ");
  77     fSecondImDtheta = ( TProfile*)list->FindObject("Second_FlowPro_ImDtheta_LYZ");
  78     fFirstr0theta   = ( TProfile*)list->FindObject("First_FlowPro_r0theta_LYZ");
  79   }
  80
  81 }
  82
  83 //-----------------------------------------------------------------------
  84 void AliFlowLYZEventPlane::CalculateRPandW(AliFlowVector aQ)
  85 {
  86   //declare variables
  87   Int_t iNtheta = AliFlowLYZConstants::kTheta;
  88   Double_t dCosTerm = 0;
  89   Double_t dSinTerm = 0;
  90   TComplex cDtheta;
  91   TComplex cRatio;
  92
  93   for (Int_t theta=0;theta<iNtheta;theta++)     {
  94     Double_t dTheta = ((float)theta/iNtheta)*TMath::Pi()/2;
  95     //Calculate Qtheta
  96     Double_t dQtheta = aQ.X()*cos(2*dTheta)+aQ.Y()*sin(2*dTheta);  //get Qtheta from Q vector
  97
  98     //get R0
  99     Double_t dR0 = fFirstr0theta->GetBinContent(theta+1);
 100     //cerr<<"dR0 = "<<dR0<<endl;
 101
 102     //get Dtheta
 103     Double_t dReDtheta = fSecondReDtheta->GetBinContent(theta+1);
 104     //cerr<<"dReDtheta = "<<dReDtheta<<endl;
 105     Double_t dImDtheta = fSecondImDtheta->GetBinContent(theta+1);
 106     //cerr<<"dImDtheta = "<<dImDtheta<<endl;
 107     cDtheta(dReDtheta,dImDtheta);
 108
 109     TComplex cExpo(0.,dR0*dQtheta);                  //Complex number: 0 +(i r0 Qtheta)
 110     if (cDtheta.Rho()!=0.) { cRatio =(TComplex::Exp(cExpo))/cDtheta; } //(e^(i r0 Qtheta))/Dtheta
 111     else { cRatio(0.,0.); }
 112
 113     //sum over theta
 114     dCosTerm += cRatio.Re() * TMath::Cos(2*dTheta);    //Re{(e^(i r0 Qtheta))/Dtheta } cos(2 theta)
 115     dSinTerm += cRatio.Re() * TMath::Sin(2*dTheta);    //Re{(e^(i r0 Qtheta))/Dtheta } sin(2 theta)
 116
 117   }//loop over theta
 118
 119   //average over theta
 120   dCosTerm /= iNtheta;
 121   dSinTerm /= iNtheta;
 122   //cerr<<"cosTerm & sinTerm are: "<<dCosTerm<<" & "<<dSinTerm<<endl;
 123
 124   //calculate fWR
 125   fWR = TMath::Sqrt(dCosTerm*dCosTerm + dSinTerm*dSinTerm);
 126
 127   //calculate fRP
 128   fPsi = 0.5*TMath::ATan2(dSinTerm,dCosTerm);   //takes care of the signs correctly!
 129   if (fPsi < 0.) { fPsi += TMath::Pi(); }       //to shift distribution from (-pi/2 to pi/2) to (0 to pi)
 130
 131 }
 132