[u/mrichter/AliRoot.git] / ITS / AliITSsimulationSPD.cxx

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

/*
$Id$
*/

#include <Riostream.h>
#include <TGeoGlobalMagField.h>
#include <TH1.h>
#include <TString.h>
#include "AliITS.h"
#include "AliITSdigitSPD.h"
#include "AliITShit.h"
#include "AliITSmodule.h"
#include "AliITSpList.h"
#include "AliITSCalibrationSPD.h"
#include "AliITSsegmentationSPD.h"
#include "AliITSsimulationSPD.h"
#include "AliLog.h"
#include "AliRun.h"
#include "AliMagF.h"
#include "AliMathBase.h"

//#define DEBUG

ClassImp(AliITSsimulationSPD)
////////////////////////////////////////////////////////////////////////
//  Version: 1
//  Modified by D. Elia, G.E. Bruno, H. Tydesjo 
//  Fast diffusion code by Bjorn S. Nilsen
//  March-April 2006
//  October     2007: GetCalibrationObjects() removed
//
//  Version: 0
//  Written by Boris Batyunya
//  December 20 1999
//
//
// AliITSsimulationSPD is to do the simulation of SPDs.
//
////////////////////////////////////////////////////////////////////////

//______________________________________________________________________
AliITSsimulationSPD::AliITSsimulationSPD():
AliITSsimulation(),
fHis(0),
fSPDname(),
fCoupling(),
fLorentz(kFALSE),
fTanLorAng(0),
fStrobe(kTRUE),
fStrobeLenght(4),
fStrobePhase(-12.5e-9){
   // Default constructor.
   // Inputs:
   //    none.
   // Outputs:
   //    none.
   // Return:
   //    A default constructed AliITSsimulationSPD class.

   AliDebug(1,Form("Calling default constructor"));
//    Init();
}
//______________________________________________________________________
AliITSsimulationSPD::AliITSsimulationSPD(AliITSDetTypeSim *dettyp):
AliITSsimulation(dettyp),
fHis(0),
fSPDname(),
fCoupling(),
fLorentz(kFALSE),
fTanLorAng(0),
fStrobe(kTRUE),
fStrobeLenght(4),
fStrobePhase(-12.5e-9){
   // standard constructor
   // Inputs:
   //    AliITSsegmentation *seg  A pointer to the segmentation class
   //                             to be used for this simulation
   //    AliITSCalibration     *resp A pointer to the responce class to
   //                             be used for this simulation
   // Outputs:
   //    none.
   // Return:
   //    A default constructed AliITSsimulationSPD class.

   AliDebug(1,Form("Calling standard constructor "));
   Init();
}
//______________________________________________________________________
void AliITSsimulationSPD::Init(){
   // Initilization
   // Inputs:
   //    none.
   // Outputs:
   //    none.
   // Return:
   //    none.
   const Double_t kmictocm = 1.0e-4; // convert microns to cm.

   SetModuleNumber(0);
   SetEventNumber(0);
   SetMap(new AliITSpList(GetNPixelsZ(),GetNPixelsX()));
   AliITSSimuParam* simpar = fDetType->GetSimuParam();
   AliITSsegmentationSPD* seg = (AliITSsegmentationSPD*)GetSegmentationModel(0);
   Double_t bias = simpar->GetSPDBiasVoltage();
//    cout << "Bias Voltage --> " << bias << endl; // dom    
   simpar->SetDistanceOverVoltage(kmictocm*seg->Dy(),bias);
// set kind of coupling ("old" or "new")
   char opt[20];
   simpar->GetSPDCouplingOption(opt);
   char *old = strstr(opt,"old");
   if (old) {
       fCoupling=2;
   } else {
       fCoupling=1;
   } // end if
   SetLorentzDrift(simpar->GetSPDLorentzDrift());
   if (fLorentz) SetTanLorAngle(simpar->GetSPDLorentzHoleWeight());
   //SetStrobeGeneration(kFALSE);
   if (fStrobe) GenerateStrobePhase();
}
//______________________________________________________________________
Bool_t AliITSsimulationSPD::SetTanLorAngle(Double_t WeightHole) {
    // This function set the Tangent of the Lorentz angle. 
    // A weighted average is used for electrons and holes 
    // Input: Double_t WeightHole: wheight for hole: it should be in the range [0,1]
    // output: Bool_t : kTRUE in case of success
    //
    if(!fDetType) {
      AliError("AliITSsimulationSPD::SetTanLorAngle: AliITSDetTypeSim* fDetType not set ");
      return kFALSE;}
    if(WeightHole<0) {
       WeightHole=0.;
       AliWarning("AliITSsimulationSPD::SetTanLorAngle: You have asked for negative Hole weight");
       AliWarning("AliITSsimulationSPD::SetTanLorAngle: I'm going to use only electrons");
    }
    if(WeightHole>1) {
       WeightHole=1.;
       AliWarning("AliITSsimulationSPD::SetTanLorAngle: You have asked for weight > 1");
       AliWarning("AliITSsimulationSPD::SetTanLorAngle: I'm going to use only holes");
    }
    Double_t WeightEle=1.-WeightHole;
    AliITSSimuParam* simpar = fDetType->GetSimuParam();
    AliMagF* fld = (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
    if (!fld) AliFatal("The field is not initialized");
    Double_t bz = fld->SolenoidField();
    fTanLorAng = TMath::Tan(WeightHole*simpar->LorentzAngleHole(bz) +
                             WeightEle*simpar->LorentzAngleElectron(bz));
    return kTRUE;
}
//______________________________________________________________________
AliITSsimulationSPD::~AliITSsimulationSPD(){
   // destructor
   // Inputs:
   //    none.
   // Outputs:
   //    none.
   // Return:
   //     none.

   if (fHis) {
       fHis->Delete(); 
       delete fHis;     
   } // end if fHis
}
//______________________________________________________________________
AliITSsimulationSPD::AliITSsimulationSPD(const 
						   AliITSsimulationSPD 
						   &s) : AliITSsimulation(s),
fHis(s.fHis),
fSPDname(s.fSPDname),
fCoupling(s.fCoupling),
fLorentz(s.fLorentz),
fTanLorAng(s.fTanLorAng),
fStrobe(s.fStrobe),
fStrobeLenght(s.fStrobeLenght),
fStrobePhase(s.fStrobePhase){
   //     Copy Constructor
   // Inputs:
   //    AliITSsimulationSPD &s The original class for which
   //                                this class is a copy of
   // Outputs:
   //    none.
   // Return:

}
//______________________________________________________________________
AliITSsimulationSPD&  AliITSsimulationSPD::operator=(const 
                                          AliITSsimulationSPD &s){
   //    Assignment operator
   // Inputs:
   //    AliITSsimulationSPD &s The original class for which
   //                                this class is a copy of
   // Outputs:
   //    none.
   // Return:

   if(&s == this) return *this;
   this->fHis = s.fHis;
   fCoupling  = s.fCoupling;
   fSPDname   = s.fSPDname;
   fLorentz   = s.fLorentz;
   fTanLorAng = s.fTanLorAng;
   fStrobe       = s.fStrobe;
   fStrobeLenght = s.fStrobeLenght;
   fStrobePhase  = s.fStrobePhase;
   return *this;
}
/*
//______________________________________________________________________
AliITSsimulation&  AliITSsimulationSPD::operator=(const 
                                          AliITSsimulation &s){
   //    Assignment operator
   // Inputs:
   //    AliITSsimulationSPD &s The original class for which
   //                                this class is a copy of
   // Outputs:
   //    none.
   // Return:

   if(&s == this) return *this;
   Error("AliITSsimulationSPD","Not allowed to make a = with "
         "AliITSsimulationSPD","Using default creater instead");

   return *this;
}
*/
//______________________________________________________________________
void AliITSsimulationSPD::InitSimulationModule(Int_t module, Int_t event){
   //  This function creates maps to build the list of tracks for each
   //  summable digit. Inputs defined by base class.
   //  Inputs:
   //    Int_t module   // Module number to be simulated
   //    Int_t event    // Event number to be simulated
   //  Outputs:
   //    none
   //  Returns:
   //    none

   AliDebug(1,Form("(module=%d,event=%d)",module,event));
   const Double_t kmictocm = 1.0e-4; // convert microns to cm.
   AliITSSimuParam* simpar = fDetType->GetSimuParam();
   AliITSsegmentationSPD* seg = (AliITSsegmentationSPD*)GetSegmentationModel(0);
   SetModuleNumber(module);
   SetEventNumber(event);
   simpar->SetDistanceOverVoltage(kmictocm*seg->Dy(),simpar->GetSPDBiasVoltage(module)); 
   ClearMap();
}
//_____________________________________________________________________
void AliITSsimulationSPD::SDigitiseModule(AliITSmodule *mod,Int_t,
                                              Int_t event){
   //  This function begins the work of creating S-Digits.  Inputs defined
   //  by base class.
   //  Inputs:
   //    AliITSmodule *mod  //  module
   //    Int_t              //  not used
   //    Int_t event        //  Event number
   //  Outputs:
   //    none
   //  Return:
   //    test              //  test returns kTRUE if the module contained hits
   //                      //  test returns kFALSE if it did not contain hits

   AliDebug(1,Form("(mod=%p, ,event=%d)",mod,event));
   if(!(mod->GetNhits())){
       AliDebug(1,Form("In event %d module %d there are %d hits returning.",
			event, mod->GetIndex(),mod->GetNhits()));
       return;// if module has no hits don't create Sdigits
   } // end if
   SetModuleNumber(mod->GetIndex());
   if (fStrobe) if(event != GetEventNumber()) GenerateStrobePhase(); 
   SetEventNumber(event);
   InitSimulationModule( GetModuleNumber() , event );
   // HitToSDigit(mod);
   HitToSDigitFast(mod);
  if (fDetType->GetSimuParam()->GetSPDAddNoisyFlag())   AddNoisyPixels();
  if (fDetType->GetSimuParam()->GetSPDRemoveDeadFlag()) RemoveDeadPixels();

//    cout << "After Remove in SDigitiseModule !!!!!" << endl; // dom
//    cout << "Module " << mod->GetIndex() << " Event " << event << endl; // dom
   WriteSDigits();
   ClearMap();
}
//______________________________________________________________________
void AliITSsimulationSPD::WriteSDigits(){
   //  This function adds each S-Digit to pList
   //  Inputs:
   //    none.
   //  Outputs:
   //    none.
   //  Return:
   //    none
   Int_t ix, nix, iz, niz;
   static AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");

   AliDebug(1,Form("Writing SDigits for module %d",GetModuleNumber()));
//    cout << "WriteSDigits for module " << GetModuleNumber() << endl; // dom
   GetMap()->GetMaxMapIndex(niz, nix);
   for(iz=0; iz<niz; iz++)for(ix=0; ix<nix; ix++){
       if(GetMap()->GetSignalOnly(iz,ix)>0.0){
//            cout << " Signal gt 0  iz ix " << iz << ix << " Module " << GetModuleNumber() << endl; // dom
           aliITS->AddSumDigit(*(GetMap()->GetpListItem(iz,ix)));
	    if(AliDebugLevel()>0) {
	      AliDebug(1,Form("%d, %d",iz,ix));
	      cout << *(GetMap()->GetpListItem(iz,ix)) << endl;
           } // end if GetDebug
       } // end if GetMap()->GetSignalOnly(iz,ix)>0.0
   } // end for iz,ix
   return; 
}
//______________________________________________________________________
void AliITSsimulationSPD::FinishSDigitiseModule(){
   //  This function calls SDigitsToDigits which creates Digits from SDigits
   //  Inputs:
   //    none
   //  Outputs:
   //    none
   //  Return
   //    none

   AliDebug(1,"()");
//    cout << "FinishSDigitiseModule for module " << GetModuleNumber() << endl; // dom
   FrompListToDigits(); // Charge To Signal both adds noise and
   ClearMap();
   return;
}
//______________________________________________________________________
void AliITSsimulationSPD::DigitiseModule(AliITSmodule *mod,Int_t,
                                             Int_t event){
   //  This function creates Digits straight from the hits and then adds
   //  electronic noise to the digits before adding them to pList
   //  Each of the input variables is passed along to HitToSDigit
   //  Inputs:
   //    AliITSmodule *mod     module
   //    Int_t                 Dummy.
   //    Int_t                 Dummy
   //  Outputs:
   //     none.
   //  Return:
   //    none.

   if (fStrobe) if(event != GetEventNumber()) GenerateStrobePhase();
   AliDebug(1,Form("(mod=%p,,0)",mod));
   // HitToSDigit(mod);
   InitSimulationModule( mod->GetIndex(), event );
   HitToSDigitFast(mod);
   
  if (fDetType->GetSimuParam()->GetSPDAddNoisyFlag())   AddNoisyPixels();
  if (fDetType->GetSimuParam()->GetSPDRemoveDeadFlag()) RemoveDeadPixels();
//    cout << "After Remove in DigitiseModule in module " << mod->GetIndex() << endl; // dom
   FrompListToDigits();
   ClearMap();
}
//______________________________________________________________________
void AliITSsimulationSPD::HitToSDigit(AliITSmodule *mod){
   // Does the charge distributions using Gaussian diffusion charge charing.
   // Inputs:
   //    AliITSmodule *mod  Pointer to this module
   // Output:
   //    none.
   // Return:
   //    none.
   const Double_t kmictocm = 1.0e-4; // convert microns to cm.
   const Double_t kBunchLenght = 25e-9; // LHC clock
   TObjArray *hits = mod->GetHits();
   Int_t nhits = hits->GetEntriesFast();
   Int_t h,ix,iz,i;
   Int_t idtrack;
   Double_t x0=0.0,x1=0.0,y0=0.0,y1=0.0,z0=0.0,z1=0.0,de=0.0,ld=0.0;
   Double_t x,y,z,t,tp,st,dt=0.2,el,sig,sigx,sigz,fda;
   AliITSsegmentationSPD* seg = (AliITSsegmentationSPD*)GetSegmentationModel(0);
   AliITSSimuParam *simpar = fDetType->GetSimuParam();
   Double_t thick = 0.5*kmictocm*seg->Dy();  // Half Thickness
   simpar->GetSPDSigmaDiffusionAsymmetry(fda);  //

   AliDebug(1,Form("(mod=%p) fCoupling=%d",mod,fCoupling));
   if(nhits<=0) return;
   for(h=0;h<nhits;h++){
     if(AliDebugLevel()>0) {
	AliDebug(1,Form("Hits, %d", h));
	cout << *(mod->GetHit(h)) << endl;
     } // end if GetDebug
     // Check if the hit is inside readout window
     if (fStrobe)
     if ((mod->GetHit(h)->GetTOF() < fStrobePhase) ||
	  (mod->GetHit(h)->GetTOF() > (fStrobePhase+(Double_t)fStrobeLenght*kBunchLenght))) continue;
       if(!mod->LineSegmentL(h,x0,x1,y0,y1,z0,z1,de,idtrack)) continue;
       st = TMath::Sqrt(x1*x1+y1*y1+z1*z1);
       if(st>0.0){
           st = (Double_t)((Int_t)(st/kmictocm)); // number of microns
           if(st<=1.0) st = 1.0;
           dt = 1.0/st;
           for(t=0.0;t<1.0;t+=dt){ // Integrate over t
               tp  = t+0.5*dt;
               x   = x0+x1*tp;
               y   = y0+y1*tp;
               z   = z0+z1*tp;
               if(!(seg->LocalToDet(x,z,ix,iz))) continue; // outside
               //el  = res->GeVToCharge((Double_t)(dt*de));
               el  = dt * de / simpar->GetGeVToCharge();
               if(GetDebug(1)){
                   if(el<=0.0) cout<<"el="<<el<<" dt="<<dt
                                   <<" de="<<de<<endl;
               } // end if GetDebug
               sig = simpar->SigmaDiffusion1D(TMath::Abs(thick + y)); 
               sigx=sig;
               sigz=sig*fda;
               if (fLorentz) ld=(y+thick)*fTanLorAng;
               SpreadChargeAsym(x,z,ix,iz,el,sigx,sigz,ld,idtrack,h);
           } // end for t
       } else { // st == 0.0 deposit it at this point
           x   = x0;
           y   = y0;
           z   = z0;
           if(!(seg->LocalToDet(x,z,ix,iz))) continue; // outside
           //el  = res->GeVToCharge((Double_t)de);
           el  = de / simpar->GetGeVToCharge();
           sig = simpar->SigmaDiffusion1D(TMath::Abs(thick + y));
           sigx=sig;
           sigz=sig*fda;
           if (fLorentz) ld=(y+thick)*fTanLorAng;
           SpreadChargeAsym(x,z,ix,iz,el,sigx,sigz,ld,idtrack,h);
       } // end if st>0.0

   } // Loop over all hits h

       // Coupling
       switch (fCoupling) {
       default:
           break;
       case 1: //case 3:
           for(i=0;i<GetMap()->GetEntries();i++) 
               if(GetMap()->GetpListItem(i)==0) continue;
               else{
                   GetMap()->GetMapIndex(GetMap()->GetpListItem(i)->GetIndex(),iz,ix);
                   SetCoupling(iz,ix,idtrack,h);
               } // end for i
           break;
       case 2: // case 4:
           for(i=0;i<GetMap()->GetEntries();i++) 
               if(GetMap()->GetpListItem(i)==0) continue;
               else{
                   GetMap()->GetMapIndex(GetMap()->GetpListItem(i)->GetIndex(),iz,ix);
                   SetCouplingOld(iz,ix,idtrack,h);
               } // end for i
           break;
       } // end switch
   if(GetDebug(2))Info("HitToSDigit","Finished fCoupling=%d",fCoupling);
}
//______________________________________________________________________
void AliITSsimulationSPD::HitToSDigitFast(AliITSmodule *mod){
   // Does the charge distributions using Gaussian diffusion charge charing.    // Inputs:
   //    AliITSmodule *mod  Pointer to this module
   // Output:
   //    none.
   // Return:
   //    none.
   const Double_t kmictocm = 1.0e-4; // convert microns to cm.
   const Int_t kn10=10;
   const Double_t kti[kn10]={7.443716945e-3,2.166976971e-1,3.397047841e-1,
                           4.325316833e-1,4.869532643e-1,5.130467358e-1,
                           5.674683167e-1,6.602952159e-1,7.833023029e-1,
                           9.255628306e-1};
   const Double_t kwi[kn10]={1.477621124e-1,1.346333597e-1,1.095431813e-1,
                           7.472567455e-2,3.333567215e-2,3.333567215e-2,
                           7.472567455e-2,1.095431813e-1,1.346333597e-1,
                           1.477621124e-1};
   const Double_t kBunchLenght = 25e-9; // LHC clock
   TObjArray *hits = mod->GetHits();
   Int_t nhits = hits->GetEntriesFast();
   Int_t h,ix,iz,i;
   Int_t idtrack;
   Double_t x0=0.0,x1=0.0,y0=0.0,y1=0.0,z0=0.0,z1=0.0,de=0.0,ld=0.0;
   Double_t x,y,z,t,st,el,sig,sigx,sigz,fda;
   AliITSsegmentationSPD* seg = (AliITSsegmentationSPD*)GetSegmentationModel(0);
   AliITSSimuParam* simpar = fDetType->GetSimuParam();
   Double_t thick = 0.5*kmictocm*seg->Dy();  // Half thickness
   simpar->GetSPDSigmaDiffusionAsymmetry(fda);
//    cout << "Half Thickness " << thick << endl;  // dom
//    cout << "Diffusion asymm " << fda << endl;  // dom

   AliDebug(1,Form("(mod=%p) fCoupling=%d",mod,fCoupling));
   if(nhits<=0) return;
   for(h=0;h<nhits;h++){
     if(AliDebugLevel()>0) {
       AliDebug(1,Form("Hits, %d", h));
       cout << *(mod->GetHit(h)) << endl;
     } // end if GetDebug
     // Check if the hit is inside readout window
     if (fStrobe)
     if ((mod->GetHit(h)->GetTOF() < fStrobePhase) ||
	  (mod->GetHit(h)->GetTOF() > (fStrobePhase+(Double_t)fStrobeLenght*kBunchLenght))) continue;
       if(!mod->LineSegmentL(h,x0,x1,y0,y1,z0,z1,de,idtrack)) continue;
       st = TMath::Sqrt(x1*x1+y1*y1+z1*z1);
       if(st>0.0) for(i=0;i<kn10;i++){ // Integrate over t
           t   = kti[i];
           x   = x0+x1*t;
           y   = y0+y1*t;
           z   = z0+z1*t;
               if(!(seg->LocalToDet(x,z,ix,iz))) continue; // outside
               el  = kwi[i]*de/simpar->GetGeVToCharge();
               if(GetDebug(1)){
                   if(el<=0.0) cout<<"el="<<el<<" kwi["<<i<<"]="<<kwi[i]
                                   <<" de="<<de<<endl;
               } // end if GetDebug
               sig = simpar->SigmaDiffusion1D(TMath::Abs(thick + y));
               sigx=sig;
               sigz=sig*fda;
               if (fLorentz) ld=(y+thick)*fTanLorAng;
               SpreadChargeAsym(x,z,ix,iz,el,sigx,sigz,ld,idtrack,h);
//                cout << "sigx sigz " << sigx << " " << sigz << endl; // dom
           } // end for i // End Integrate over t
       else { // st == 0.0 deposit it at this point
           x   = x0;
           y   = y0;
           z   = z0;
           if(!(seg->LocalToDet(x,z,ix,iz))) continue; // outside
           el  = de / simpar->GetGeVToCharge();
           sig = simpar->SigmaDiffusion1D(TMath::Abs(thick + y));
           sigx=sig;
           sigz=sig*fda;
           if (fLorentz) ld=(y+thick)*fTanLorAng;
           SpreadChargeAsym(x,z,ix,iz,el,sigx,sigz,ld,idtrack,h);
       } // end if st>0.0

   } // Loop over all hits h

       // Coupling
       switch (fCoupling) {
       default:
           break;
       case 1: // case 3:
           for(i=0;i<GetMap()->GetEntries();i++)
               if(GetMap()->GetpListItem(i)==0) continue;
               else{
                   GetMap()->GetMapIndex(GetMap()->GetpListItem(i)->GetIndex(),iz,ix);
                   SetCoupling(iz,ix,idtrack,h);
               } // end for i
           break;
       case 2: // case 4:
           for(i=0;i<GetMap()->GetEntries();i++)
               if(GetMap()->GetpListItem(i)==0) continue;
               else{
                   GetMap()->GetMapIndex(GetMap()->GetpListItem(i)->GetIndex(),iz,ix);  
                   SetCouplingOld(iz,ix,idtrack,h);
               } // end for i
           break;
       } // end switch
   if(GetDebug(2))Info("HitToSDigit","Finished fCoupling=%d",fCoupling);
}
//______________________________________________________________________
void AliITSsimulationSPD::SpreadCharge(Double_t x0,Double_t z0,
                                           Int_t ix0,Int_t iz0,
					    Double_t el,Double_t sig,Double_t ld,
					    Int_t t,Int_t hi){
   // Spreads the charge over neighboring cells. Assume charge is distributed
   // as charge(x,z) = (el/2*pi*sig*sig)*exp(-arg)
   // arg=((x-x0)*(x-x0)/2*sig*sig)+((z-z0*z-z0)/2*sig*sig)
   // if fLorentz=kTRUE, then x0=x0+ld (Lorentz drift taken into account)
   // Defined this way, the integral over all x and z is el.
   // Inputs:
   //    Double_t x0   x position of point where charge is liberated
   //    Double_t z0   z position of point where charge is liberated
   //    Int_t    ix0  row of cell corresponding to point x0
   //    Int_t    iz0  columb of cell corresponding to point z0
   //    Double_t el   number of electrons liberated in this step
   //    Double_t sig  Sigma difusion for this step (y0 dependent)
   //    Double_t ld   lorentz drift in x for this step (y0 dependent)
   //    Int_t    t    track number
   //    Int_t    ti   hit track index number
   //    Int_t    hi   hit "hit" index number
   // Outputs:
   //     none.
   // Return:
   //     none.
   const Int_t knx = 3,knz = 2;
   const Double_t kRoot2 = 1.414213562; // Sqrt(2).
   const Double_t kmictocm = 1.0e-4; // convert microns to cm.
   Int_t ix,iz,ixs,ixe,izs,ize;
   Float_t x,z;
   Double_t x1,x2,z1,z2,s,sp;
   AliITSsegmentationSPD* seg = (AliITSsegmentationSPD*)GetSegmentationModel(0);


   if(GetDebug(4)) Info("SpreadCharge","(x0=%e,z0=%e,ix0=%d,iz0=%d,el=%e,"
                        "sig=%e,t=%d,i=%d)",x0,z0,ix0,iz0,el,sig,t,hi);
   if(sig<=0.0) { // if sig<=0 No diffusion to simulate.
       GetMap()->AddSignal(iz0,ix0,t,hi,GetModuleNumber(),el);
       if(GetDebug(2)){
           cout << "sig<=0.0=" << sig << endl;
       } // end if GetDebug
       return;
   } // end if
   sp = 1.0/(sig*kRoot2);
   if(GetDebug(2)){
       cout << "sig=" << sig << " sp=" << sp << endl;
   } // end if GetDebug
   ixs = TMath::Max(-knx+ix0,0);
   ixe = TMath::Min(knx+ix0,seg->Npx()-1);
   izs = TMath::Max(-knz+iz0,0);
   ize = TMath::Min(knz+iz0,seg->Npz()-1);
   for(ix=ixs;ix<=ixe;ix++) for(iz=izs;iz<=ize;iz++){
       seg->DetToLocal(ix,iz,x,z); // pixel center
       x1  = x;
       z1  = z;
       x2  = x1 + 0.5*kmictocm*seg->Dpx(ix); // Upper
       x1 -= 0.5*kmictocm*seg->Dpx(ix);  // Lower
       z2  = z1 + 0.5*kmictocm*seg->Dpz(iz); // Upper
       z1 -= 0.5*kmictocm*seg->Dpz(iz);  // Lower
       x1 -= x0+ld; // Distance from where track traveled (taking into account the Lorentz drift)
       x2 -= x0+ld; // Distance from where track traveled (taking into account the Lorentz drift)
       z1 -= z0; // Distance from where track traveled
       z2 -= z0; // Distance from where track traveled
       s   = 0.25; // Correction based on definision of Erfc
       s  *= AliMathBase::ErfcFast(sp*x1) - AliMathBase::ErfcFast(sp*x2);
       if(GetDebug(3)){
           cout <<"el="<<el<<" ix0="<<ix0<<" ix="<<ix<<" x0="<<x<<
               " iz0="<<iz0<<" iz="<<iz<<" z0="<<z<< 
               " sp*x1="<<sp*x1<<" sp*x2="<<sp*x2<<" s="<<s;
       } // end if GetDebug
       s  *= AliMathBase::ErfcFast(sp*z1) - AliMathBase::ErfcFast(sp*z2);
       if(GetDebug(3)){
           cout<<" sp*z1="<<sp*z1<<" sp*z2="<<sp*z2<<" s="<<s<< endl;
       } // end if GetDebug
       GetMap()->AddSignal(iz,ix,t,hi,GetModuleNumber(),s*el);
   } // end for ix, iz
}
//______________________________________________________________________
void AliITSsimulationSPD::SpreadChargeAsym(Double_t x0,Double_t z0,
                                           Int_t ix0,Int_t iz0,
                                           Double_t el,Double_t sigx,Double_t sigz,
                                           Double_t ld,Int_t t,Int_t hi){
   // Spreads the charge over neighboring cells. Assume charge is distributed
   // as charge(x,z) = (el/2*pi*sigx*sigz)*exp(-arg)
   // arg=((x-x0)*(x-x0)/2*sigx*sigx)+((z-z0*z-z0)/2*sigz*sigz)
   // if fLorentz=kTRUE, then x0=x0+ld (Lorentz drift taken into account)
   // Defined this way, the integral over all x and z is el.
   // Inputs:
   //    Double_t x0   x position of point where charge is liberated
   //    Double_t z0   z position of point where charge is liberated
   //    Int_t    ix0  row of cell corresponding to point x0
   //    Int_t    iz0  columb of cell corresponding to point z0
   //    Double_t el   number of electrons liberated in this step
   //    Double_t sigx Sigma difusion along x for this step (y0 dependent)
   //    Double_t sigz Sigma difusion along z for this step (y0 dependent)
   //    Double_t ld   lorentz drift in x for this stip (y0 dependent)
   //    Int_t    t    track number
   //    Int_t    ti   hit track index number
   //    Int_t    hi   hit "hit" index number
   // Outputs:
   //     none.
   // Return:
   //     none.
   const Int_t knx = 3,knz = 2;
   const Double_t kRoot2 = 1.414213562; // Sqrt(2).
   const Double_t kmictocm = 1.0e-4; // convert microns to cm.
   Int_t ix,iz,ixs,ixe,izs,ize;
   Float_t x,z;
   Double_t x1,x2,z1,z2,s,spx,spz;
   AliITSsegmentationSPD* seg = (AliITSsegmentationSPD*)GetSegmentationModel(0);


   if(GetDebug(4)) Info("SpreadChargeAsym","(x0=%e,z0=%e,ix0=%d,iz0=%d,el=%e,"
                        "sigx=%e, sigz=%e, t=%d,i=%d)",x0,z0,ix0,iz0,el,sigx,sigz,t,hi);
   if(sigx<=0.0 || sigz<=0.0) { // if sig<=0 No diffusion to simulate.
       GetMap()->AddSignal(iz0,ix0,t,hi,GetModuleNumber(),el);
       if(GetDebug(2)){
           cout << "sigx<=0.0=" << sigx << endl;
           cout << "sigz<=0.0=" << sigz << endl;
       } // end if GetDebug
       return;
   } // end if
   spx = 1.0/(sigx*kRoot2);     spz = 1.0/(sigz*kRoot2);
   if(GetDebug(2)){
       cout << "sigx=" << sigx << " spx=" << spx << endl;
       cout << "sigz=" << sigz << " spz=" << spz << endl;
   } // end if GetDebug
   ixs = TMath::Max(-knx+ix0,0);
   ixe = TMath::Min(knx+ix0,seg->Npx()-1);
   izs = TMath::Max(-knz+iz0,0);
   ize = TMath::Min(knz+iz0,seg->Npz()-1);
   for(ix=ixs;ix<=ixe;ix++) for(iz=izs;iz<=ize;iz++){
       seg->DetToLocal(ix,iz,x,z); // pixel center
       x1  = x;
       z1  = z;
       x2  = x1 + 0.5*kmictocm*seg->Dpx(ix); // Upper
       x1 -= 0.5*kmictocm*seg->Dpx(ix);  // Lower
       z2  = z1 + 0.5*kmictocm*seg->Dpz(iz); // Upper
       z1 -= 0.5*kmictocm*seg->Dpz(iz);  // Lower
       x1 -= x0+ld; // Distance from where track traveled (taking into account the Lorentz drift)
       x2 -= x0+ld; // Distance from where track traveled (taking into account the Lorentz drift)
       z1 -= z0; // Distance from where track traveled
       z2 -= z0; // Distance from where track traveled
       s   = 0.25; // Correction based on definision of Erfc
       s  *= AliMathBase::ErfcFast(spx*x1) - AliMathBase::ErfcFast(spx*x2);
       if(GetDebug(3)){
           cout <<"el="<<el<<" ix0="<<ix0<<" ix="<<ix<<" x0="<<x<<
               " iz0="<<iz0<<" iz="<<iz<<" z0="<<z<< 
               " spx*x1="<<spx*x1<<" spx*x2="<<spx*x2<<" s="<<s;
       } // end if GetDebug
       s  *= AliMathBase::ErfcFast(spz*z1) - AliMathBase::ErfcFast(spz*z2);
       if(GetDebug(3)){
           cout<<" spz*z1="<<spz*z1<<" spz*z2="<<spz*z2<<" s="<<s<< endl;
       } // end if GetDebug
       GetMap()->AddSignal(iz,ix,t,hi,GetModuleNumber(),s*el);
   } // end for ix, iz
}
//______________________________________________________________________
void AliITSsimulationSPD::RemoveDeadPixels(){
  // Removes dead pixels on each module (ladder)
  // This should be called before going from sdigits to digits (FrompListToDigits)
  Int_t mod = GetModuleNumber();
  AliITSCalibrationSPD* calObj = (AliITSCalibrationSPD*) fDetType->GetCalibrationModel(mod);

  Int_t nrDead = calObj->GetNrBad();
  for (Int_t i=0; i<nrDead; i++) {
    GetMap()->DeleteHit(calObj->GetBadColAt(i), calObj->GetBadRowAt(i));
  }
}
//______________________________________________________________________
void AliITSsimulationSPD::AddNoisyPixels() {
  // Adds noisy pixels on each module (ladder)
  // This should be called before going from sdigits to digits (FrompListToDigits)
  Int_t mod = GetModuleNumber();
  AliITSCalibrationSPD* calObj = (AliITSCalibrationSPD*) fDetType->GetSPDNoisyModel(mod);

  Int_t nrNoisy = calObj->GetNrBad();
  for (Int_t i=0; i<nrNoisy; i++) {
    // adding 10 times the threshold will for sure make this pixel fire...
    GetMap()->AddNoise(calObj->GetBadColAt(i), calObj->GetBadRowAt(i), mod, 10*GetThreshold());
  }
}
//______________________________________________________________________
void AliITSsimulationSPD::FrompListToDigits(){
   // add noise and electronics, perform the zero suppression and add the
   // digit to the list
   // Inputs:
   //    none.
   // Outputs:
   //    none.
   // Return:
   //    none.
   static AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");
   Int_t j,ix,iz;
   Double_t  electronics;
   Double_t sig;
   const Int_t    knmaxtrk=AliITSdigit::GetNTracks();
   static AliITSdigitSPD dig;
   AliITSSimuParam *simpar = fDetType->GetSimuParam();
   if(GetDebug(1)) Info("FrompListToDigits","()");
   for(iz=0; iz<GetNPixelsZ(); iz++) for(ix=0; ix<GetNPixelsX(); ix++){
// NEW (for the moment plugged by hand, in the future possibly read from Data Base)
// here parametrize the efficiency of the pixel along the row for the test columns (1,9,17,25)
//        if(iz==1 || iz == 9 || iz == 17 || iz == 25) {
//        Double_t eff,p1=0.,p2=0.; 
//        Double_t x=ix;
//        switch (iz) {
//          case 1:   p1=0.63460;p2=0.42438E-01;break;  
//          case 9:   p1=0.41090;p2=0.75914E-01;break;
//	  case 17:  p1=0.31883;p2=0.91502E-01;break;
//	  case 25:  p1=0.48828;p2=0.57975E-01;break;
//         } // end switch
//          eff=1.-p1*exp(-p2*x);
//          if (gRandom->Rndm() >= eff) continue;
//        } // end  if 
// END parametrize the efficiency
// 
       electronics = simpar->ApplySPDBaselineAndNoise();
       UpdateMapNoise(ix,iz,electronics);
       //
       // Apply Threshold and write Digits.
       sig = GetMap()->GetSignalOnly(iz,ix);
       FillHistograms(ix,iz,sig+electronics);
       if(GetDebug(3)){
           cout<<sig<<"+"<<electronics<<">threshold("<<ix<<","<<iz
               <<")="<<GetThreshold() <<endl;
       } // end if GetDebug
      // if (sig+electronics <= GetThreshold()) continue;
       if (GetMap()->GetSignal(iz,ix) <= GetThreshold()) continue;
       dig.SetCoord1(iz);
       dig.SetCoord2(ix);
       dig.SetSignal(1);

//        dig.SetSignalSPD((Int_t) GetMap()->GetSignal(iz,ix));
       Double_t aSignal =  GetMap()->GetSignal(iz,ix);
       if (TMath::Abs(aSignal)>2147483647.0) {
         //PH 2147483647 is the max. integer
         //PH This apparently is a problem which needs investigation
         AliWarning(Form("Too big or too small signal value %f",aSignal));
         aSignal = TMath::Sign((Double_t)2147483647,aSignal);
       }
       dig.SetSignalSPD((Int_t)aSignal);

       for(j=0;j<knmaxtrk;j++){
           if (j<GetMap()->GetNEntries()) {
               dig.SetTrack(j,GetMap()->GetTrack(iz,ix,j));
               dig.SetHit(j,GetMap()->GetHit(iz,ix,j));
           }else { // Default values
               dig.SetTrack(j,-3);
               dig.SetHit(j,-1);
           } // end if GetMap()
       } // end for j
       if(GetDebug(3)){
           cout<<iz<<","<<ix<<","<<*(GetMap()->GetpListItem(iz,ix))<<endl;
       } // end if GetDebug
       aliITS->AddSimDigit(0,&dig);
       // simulate fo signal response for this pixel hit:
       fDetType->ProcessSPDDigitForFastOr(fModule, dig.GetCoord1(), dig.GetCoord2());
   } //  for ix/iz
}
//______________________________________________________________________
void AliITSsimulationSPD::CreateHistograms(){
   // create 1D histograms for tests
   // Inputs:
   //    none.
   // Outputs:
   //    none.
   // Return:
   //     none.

   if(GetDebug(1)) Info("CreateHistograms","create histograms");

   fHis = new TObjArray(GetNPixelsZ());
   fSPDname="spd_";
   for(Int_t i=0;i<GetNPixelsZ();i++) {
       Char_t pixelz[4];
       snprintf(pixelz,3,"%d",i);
       fSPDname.Append(pixelz);
       fHis->AddAt(new TH1F(fSPDname.Data(),"SPD maps",
                            GetNPixelsX(),0.,(Double_t)GetNPixelsX()),i);
   } // end for i
}
//______________________________________________________________________
void AliITSsimulationSPD::FillHistograms(Int_t ix,Int_t iz,Double_t v){
   // Fill the histogram
   // Inputs:
   //    none.
   // Outputs:
   //    none.
   // Return:
   //     none.

   if(!GetHistArray()) return; // Only fill if setup.
   if(GetDebug(2)) Info("FillHistograms","fill histograms");
   GetHistogram(iz)->Fill(ix,v);
}
//______________________________________________________________________
void AliITSsimulationSPD::ResetHistograms(){
   // Reset histograms for this detector
   // Inputs:
   //    none.
   // Outputs:
   //    none.
   // Return:
   //     none.

   if(!GetHistArray()) return; // Only fill if setup.
   if(GetDebug(2)) Info("FillHistograms","fill histograms");
   for ( int i=0;i<GetNPixelsZ();i++ ) {
       if (fHis->At(i))    ((TH1F*)fHis->At(i))->Reset();
   } // end for i
}

//______________________________________________________________________
void AliITSsimulationSPD::SetCoupling(Int_t col, Int_t row, Int_t ntrack,
				      Int_t idhit) {
   //  Take into account the coupling between adiacent pixels.
   //  The parameters probcol and probrow are the probability of the
   //  signal in one pixel shared in the two adjacent pixels along
   //  the column and row direction, respectively.
   //  Note pList is goten via GetMap() and module is not need any more.
   //  Otherwise it is identical to that coded by Tiziano Virgili (BSN).
   //Begin_Html
   /*
     <img src="picts/ITS/barimodel_3.gif">
     </pre>
     <br clear=left>
     <font size=+2 color=red>
     <a href="mailto:tiziano.virgili@cern.ch"></a>.
     </font>
     <pre>
   */
   //End_Html
   // Inputs:
   //    Int_t col            z cell index
   //    Int_t row            x cell index
   //    Int_t ntrack         track incex number
   //    Int_t idhit          hit index number
   // Outputs:
   //    none.
   // Return:
   //     none.
   Int_t j1,j2,flag=0;
   Double_t pulse1,pulse2;
   Double_t couplR=0.0,couplC=0.0;
   Double_t xr=0.;

   GetCouplings(couplC,couplR);
   if(GetDebug(3)) Info("SetCoupling","(col=%d,row=%d,ntrack=%d,idhit=%d) "
                        "Calling SetCoupling couplC=%e couplR=%e",
                        col,row,ntrack,idhit,couplC,couplR);
   j1 = col;
   j2 = row;
   pulse1 = GetMap()->GetSignalOnly(col,row);
   pulse2 = pulse1;
   for (Int_t isign=-1;isign<=1;isign+=2){// loop in col direction
       do{
           j1 += isign;
           xr = gRandom->Rndm();
           if ((j1<0) || (j1>GetNPixelsZ()-1) || (xr>couplC)){
               j1 = col;
               flag = 1;
           }else{
               UpdateMapSignal(row,j1,ntrack,idhit,pulse1);
               //  flag = 0;
               flag = 1; // only first next!!
           } // end if
       } while(flag == 0);
       // loop in row direction
       do{
           j2 += isign;
           xr = gRandom->Rndm();
           if ((j2<0) || (j2>GetNPixelsX()-1) || (xr>couplR)){
               j2 = row;
               flag = 1;
           }else{
               UpdateMapSignal(j2,col,ntrack,idhit,pulse2);
               //  flag = 0;
               flag = 1; // only first next!!
           } // end if
       } while(flag == 0);
   } // for isign
}
//______________________________________________________________________
void AliITSsimulationSPD::SetCouplingOld(Int_t col, Int_t row,
               Int_t ntrack,Int_t idhit) {
   //  Take into account the coupling between adiacent pixels.
   //  The parameters probcol and probrow are the fractions of the
   //  signal in one pixel shared in the two adjacent pixels along
   //  the column and row direction, respectively.
   //Begin_Html
   /*
     <img src="picts/ITS/barimodel_3.gif">
     </pre>
     <br clear=left>
     <font size=+2 color=red>
     <a href="mailto:Rocco.Caliandro@ba.infn.it"></a>.
     </font>
     <pre>
   */
   //End_Html
   // Inputs:
   //    Int_t col            z cell index
   //    Int_t row            x cell index
   //    Int_t ntrack         track incex number
   //    Int_t idhit          hit index number
   //    Int_t module         module number
   // Outputs:
   //    none.
   // Return:
   //     none.
   Int_t j1,j2,flag=0;
   Double_t pulse1,pulse2;
   Double_t couplR=0.0,couplC=0.0;

   GetCouplings(couplC,couplR);

   //  Debugging ...
//    cout << "Threshold --> " << GetThreshold() << endl;  // dom
//    cout << "Couplings --> " << couplC << " " << couplR << endl;  // dom

   if(GetDebug(3)) Info("SetCouplingOld","(col=%d,row=%d,ntrack=%d,idhit=%d) "
                        "Calling SetCoupling couplC=%e couplR=%e",
                        col,row,ntrack,idhit,couplC,couplR);
   for (Int_t isign=-1;isign<=1;isign+=2){// loop in col direction
   pulse1 = GetMap()->GetSignalOnly(col,row);
   pulse2 = pulse1;
   j1 = col;
   j2 = row;
       do{
           j1 += isign;
           pulse1 *= couplC;
           if ((j1<0)||(j1>GetNPixelsZ()-1)||(pulse1<GetThreshold())){
               pulse1 = GetMap()->GetSignalOnly(col,row);
               j1 = col;
               flag = 1;
           }else{
               UpdateMapSignal(row,j1,ntrack,idhit,pulse1);
               // flag = 0;
               flag = 1;  // only first next !!
           } // end if
       } while(flag == 0);
       // loop in row direction
       do{
           j2 += isign;
           pulse2 *= couplR;
           if((j2<0)||(j2>(GetNPixelsX()-1))||(pulse2<GetThreshold())){
               pulse2 = GetMap()->GetSignalOnly(col,row);
               j2 = row;
               flag = 1;
           }else{
               UpdateMapSignal(j2,col,ntrack,idhit,pulse2);
               // flag = 0;
               flag = 1; // only first next!!
           } // end if
       } while(flag == 0);
   } // for isign
}
//______________________________________________________________________
void AliITSsimulationSPD::GenerateStrobePhase()
{
 // Generate randomly the strobe
 // phase w.r.t to the LHC clock
 // Done once per event
   const Double_t kBunchLenght = 25e-9; // LHC clock
   fStrobePhase = ((Double_t)gRandom->Integer(fStrobeLenght))*kBunchLenght-
                  (Double_t)fStrobeLenght*kBunchLenght+
                  kBunchLenght/2;
}