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 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *

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 * Author: The ALICE Off-line Project.                                    *

 * Contributors are mentioned in the code where appropriate.              *

 *                                                                        *

 * Permission to use, copy, modify and distribute this software and its   *

 * documentation strictly for non-commercial purposes is hereby granted   *

 * without fee, provided that the above copyright notice appears in all   *

 * copies and that both the copyright notice and this permission notice   *

 * appear in the supporting documentation. The authors make no claims     *

 * about the suitability of this software for any purpose. It is          *

 * provided "as is" without express or implied warranty.                  *

 **************************************************************************/



/* $Id$ */



//_________________________________________________________________________

// Implementation version v1 of EMCAL Manager class 

// An object of this class does not produce digits

// It is the one to use if you do want to produce outputs in TREEH 

//                  

//*-- Author: Sahal Yacoob (LBL /UCT)

//*--       : Jennifer Klay (LBL)



// This Class not stores information on all particles prior to EMCAL entry - in order to facilitate analysis.

// This is done by setting fIShunt =2, and flagging all parents of particles entering the EMCAL.



// 15/02/2002 .... Yves Schutz

//  1. fSamplingFraction and fLayerToPreshowerRatio have been removed

//  2. Timing signal is collected and added to hit



// --- ROOT system ---

#include "TPGON.h"

#include "TTUBS.h"

#include "TNode.h"

#include "TRandom.h"

#include "TTree.h"

#include "TGeometry.h"

#include "TParticle.h"



// --- Standard library ---



#include <stdio.h>

#include <string.h>

#include <stdlib.h>

#include <Rstrstream.h>

#include <Riostream.h>

#include <math.h>

// --- AliRoot header files ---



#include "AliEMCALv1.h"

#include "AliEMCALHit.h"

#include "AliEMCALGeometry.h"

#include "AliConst.h"

#include "AliRun.h"

#include "AliMC.h"



ClassImp(AliEMCALv1)





//______________________________________________________________________

AliEMCALv1::AliEMCALv1():AliEMCALv0(){

  // ctor

    fLightYieldMean = 0 ; 

    fIntrinsicAPDEfficiency = fLightFactor = fLightYieldAttenuation =   fAPDFactor = fAPDGain = fRecalibrationFactor = fAPDFactor = 0. ; 

}



//______________________________________________________________________

AliEMCALv1::AliEMCALv1(const char *name, const char *title):

    AliEMCALv0(name,title){

    // Standard Creator.



    fHits= new TClonesArray("AliEMCALHit",1000);

    gAlice->AddHitList(fHits);



    fNhits = 0;

    fIshunt     =  2; // All hits are associated with particles entering the calorimeter



    //Photoelectron statistics:

    // The light yield is a poissonian distribution of the number of

    // photons created in a plastic layer, calculated using following formula

    // NumberOfPhotons = EnergyLost * LightYieldMean* APDEfficiency *

    //              exp (-LightYieldAttenuation * DistanceToPINdiodeFromTheHit)

    // LightYieldMean is parameter calculated to be over 100000 photons per GeV (a guess)

    // APDEfficiency is 0.02655

    // fLightYieldAttenuation is 0.0045 a guess

    // TO BE FIXED

    //***** Need a method in geometry to retrieve the fiber length corresponding to each layer

    //***** See the step manager for the light attenuation calculation 

    // The number of electrons created in the APD is

    // NumberOfElectrons = APDGain * LightYield

    // The APD Gain is 300

    

    fLightYieldMean         = 10000000.;  // This is a guess

    fIntrinsicAPDEfficiency = 0.02655 ;

    fLightFactor            = fLightYieldMean * fIntrinsicAPDEfficiency ; 

    fLightYieldAttenuation  = 0.0045 ; // an other guess 

    fAPDGain                = 300. ;

    fRecalibrationFactor    = 13.418/ fLightYieldMean ;

    fAPDFactor              = (fRecalibrationFactor/100.) * fAPDGain ; 



}



//______________________________________________________________________

AliEMCALv1::~AliEMCALv1(){

    // dtor



    if ( fHits) {

	fHits->Delete();

	delete fHits;

	fHits = 0;

    }

}

//______________________________________________________________________

void AliEMCALv1::AddHit(Int_t shunt, Int_t primary, Int_t tracknumber, Int_t iparent, Float_t ienergy, 

			Int_t id, Float_t * hits,Float_t * p){

    // Add a hit to the hit list.

    // An EMCAL hit is the sum of all hits in a single segment 

    //   originating from the same enterring particle 

    Int_t hitCounter;

    

    AliEMCALHit *newHit;

    AliEMCALHit *curHit;

    Bool_t deja = kFALSE;



    newHit = new AliEMCALHit(shunt, primary, tracknumber, iparent, ienergy, id, hits, p);

    for ( hitCounter = fNhits-1; hitCounter >= 0 && !deja; hitCounter-- ) {

	curHit = (AliEMCALHit*) (*fHits)[hitCounter];

	// We add hits with the same tracknumber, while GEANT treats

	// primaries succesively

	if(curHit->GetPrimary() != primary) break;

	if( *curHit == *newHit ) {

	    *curHit = *curHit + *newHit;

	    deja = kTRUE;

	} // end if

    } // end for hitCounter



    if ( !deja ) {

	new((*fHits)[fNhits]) AliEMCALHit(*newHit);

	fNhits++;

    } // end if



    delete newHit;

}

//______________________________________________________________________

void AliEMCALv1::StepManager(void){

  // Accumulates hits as long as the track stays in a single

  // crystal or PPSD gas Cell



  Int_t          id[2];           // (layer, phi, Eta) indices

  Int_t          absid;

  // position wrt MRS and energy deposited

  Float_t        xyzte[5]={0.,0.,0.,0.,0.};// position wrt MRS, time and energy deposited

  Float_t        pmom[4]={0.,0.,0.,0.};

  TLorentzVector pos; // Lorentz vector of the track current position.

  TLorentzVector mom; // Lorentz vector of the track current momentum.

  Int_t tracknumber =  gAlice->CurrentTrack();

  Int_t primary = 0;

  static Int_t iparent = 0;

  static Float_t ienergy = 0;

  Int_t copy = 0;

  

  AliEMCALGeometry * geom = GetGeometry() ; 



  if(gMC->IsTrackEntering() && (strcmp(gMC->CurrentVolName(),"XALU") == 0)){ // This Particle in enterring the Calorimeter

    gMC->TrackPosition(pos) ;

    xyzte[0] = pos[0] ;

    xyzte[1] = pos[1] ;

    xyzte[2] = pos[2] ;

    if ( (xyzte[0]*xyzte[0] + xyzte[1]*xyzte[1])  

	 <  (geom->GetEnvelop(0)+geom->GetGap2Active()+1.5 )*(geom->GetEnvelop(0)+geom->GetGap2Active()+1.5 ) ) {

      iparent = tracknumber;

      gMC->TrackMomentum(mom);

      ienergy = mom[3]; 

      TParticle * part = 0 ;

      Int_t parent = iparent ;

      while ( parent != -1 ) { // <------------- flags this particle to be kept and

	//all the ancestors of this particle

	part = gAlice->Particle(parent) ;

	part->SetBit(kKeepBit);

	parent = part->GetFirstMother() ;

      }

    }

  }

  if(gMC->CurrentVolID(copy) == gMC->VolId("XPHI") ) { // We are in a Scintillator Layer 

    

    Float_t depositedEnergy ; 

    

    if( (depositedEnergy = gMC->Edep()) > 0.){// Track is inside a scintillator and deposits some energy

      

      gMC->TrackPosition(pos);

      xyzte[0] = pos[0];

      xyzte[1] = pos[1];

      xyzte[2] = pos[2];

      xyzte[3] = gMC->TrackTime() ;       

      

      gMC->TrackMomentum(mom);

      pmom[0] = mom[0];

      pmom[1] = mom[1];

      pmom[2] = mom[2];

      pmom[3] = mom[3];

      

      gMC->CurrentVolOffID(1, id[0]); // get the POLY copy number;

      gMC->CurrentVolID(id[1]); // get the phi number inside the layer

      absid = (id[0]-1)*(geom->GetNPhi()) + id[1];

      

      //Calculates the light yield, the number of photons produced in the

      //plastic layer 

      // Here we need to know the fiber lebgth to calculate the attenuation

     

      Float_t lengthOfFiber = 0. ;// should be retrieved from the geometry



      Float_t lightYield = gRandom->Poisson(fLightFactor * depositedEnergy *

					    exp(-fLightYieldAttenuation * lengthOfFiber)) ;

      xyzte[4] = fAPDFactor * lightYield  ;

   

      primary = gAlice->GetPrimary(tracknumber);

      AddHit(fIshunt, primary,tracknumber, iparent, ienergy, absid, xyzte, pmom);

    } // there is deposited energy

  }

}