[u/mrichter/AliRoot.git] / ITS / AliITSsimulationSSD.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 <stdio.h>
#include <stdlib.h>
#include <Riostream.h>
#include <TObjArray.h>
#include <TParticle.h>
#include <TRandom.h>
#include <TMath.h>
#include <TH1.h>

#include "AliITSmodule.h"
#include "AliITSMapA2.h"
#include "AliITSpList.h"
#include "AliITSresponseSSD.h"
#include "AliITSsegmentationSSD.h"
#include "AliITSdcsSSD.h"
#include "AliITS.h"
#include "AliITShit.h"
#include "AliITSdigitSSD.h"
#include "AliRun.h"
#include "AliITSgeom.h"
#include "AliITSsimulationSSD.h"
#include "AliITSTableSSD.h"

ClassImp(AliITSsimulationSSD)
////////////////////////////////////////////////////////////////////////
// Version: 0
// Written by Enrico Fragiacomo
// July 2000
//
// AliITSsimulationSSD is the simulation of SSDs.

//----------------------------------------------------------------------
AliITSsimulationSSD::AliITSsimulationSSD():AliITSsimulation(),
fDCS(0),
fMapA2(0),
fIonE(0.0),
fDifConst(),
fDriftVel(){
    //default Constructor
    //Inputs:
    // none.
    // Outputs:
    // none.
    // Return:
    //  A default construction AliITSsimulationSSD class
}
//----------------------------------------------------------------------
AliITSsimulationSSD::AliITSsimulationSSD(AliITSsegmentation *seg,
                                         AliITSresponse *res):
AliITSsimulation(seg,res),
fDCS(0),
fMapA2(0),
fIonE(0.0),
fDifConst(),
fDriftVel(){
    // Constructor 
    // Input:
    //   AliITSsegmentationSSD *seg  Pointer to the SSD segmentation to be used
    //   AliITSresponseSSD   *resp Pointer to the SSD responce class to be used
    // Outputs:
    //   none.
    // Return
    //   A standard constructed AliITSsimulationSSD class

    Init();
}
//----------------------------------------------------------------------
void AliITSsimulationSSD::Init(){
    // Inilizer, Inilizes all of the variable as needed in a standard place.
    // Input:
    //   AliITSsegmentationSSD *seg  Pointer to the SSD segmentation to be used
    //   AliITSresponseSSD   *resp Pointer to the SSD responce class to be used
    // Outputs:
    //   none.
    // Return
    //   none.

    Double_t noise[2] = {0.,0.};
    GetResp()->GetNoiseParam(noise[0],noise[1]); // retrieves noise parameters
    fDCS = new AliITSdcsSSD((AliITSsegmentationSSD*)GetSegmentationModel(),
                            (AliITSresponseSSD*)GetResponseModel()); 

    SetDriftVelocity(); // use default values in .h file
    SetIonizeE();       // use default values in .h file
    SetDiffConst();     // use default values in .h file
    fpList           = new AliITSpList(2,GetNStrips());
    fMapA2           = new AliITSMapA2(GetSegmentationModel());
}
//______________________________________________________________________
AliITSsimulationSSD& AliITSsimulationSSD::operator=(
                                         const AliITSsimulationSSD &s){
  // Operator =

  if(this==&s) return *this;

  this->fDCS         = new AliITSdcsSSD(*(s.fDCS));
  this->fMapA2       = s.fMapA2;
  this->fIonE        = s.fIonE;
  this->fDifConst[0] = s.fDifConst[0];
  this->fDifConst[1] = s.fDifConst[1];
  this->fDriftVel[0] = s.fDriftVel[0];
  this->fDriftVel[1] = s.fDriftVel[1];
  return *this;
}
//______________________________________________________________________
AliITSsimulationSSD& AliITSsimulationSSD::operator=(
                                         const AliITSsimulation &s){
  // Operator =

  if(this==&s) return *this;
  Error("AliITSsimulationSSD","Not allowed to make a = with "
	"AliITSsimulationSSD Using default creater instead");
  
  return *this;
}
//______________________________________________________________________
AliITSsimulationSSD::AliITSsimulationSSD(const AliITSsimulationSSD &source):
    AliITSsimulation(source){
  // copy constructor

  *this = source;
}
//______________________________________________________________________
AliITSsimulationSSD::~AliITSsimulationSSD() {
  // destructor
  delete fMapA2;
  delete fDCS;
}
//______________________________________________________________________
void AliITSsimulationSSD::InitSimulationModule(Int_t module,Int_t event){
    // Creates maps to build the list of tracks for each sumable digit
    // Inputs:
    //   Int_t module    // Module number to be simulated
    //   Int_t event     // Event number to be simulated
    // Outputs:
    //   none.
    // Return
    //    none.

    SetModuleNumber(module);
    SetEventNumber(event);
    fMapA2->ClearMap();
    fpList->ClearMap();
}
//______________________________________________________________________
void AliITSsimulationSSD::FinishSDigitiseModule(){
    // Does the Sdigits to Digits work
    // Inputs:
    //   none.
    // Outputs:
    //   none.
    // Return:
    //   none.

    FillMapFrompList(fpList);  // need to check if needed here or not????
    SDigitToDigit(fModule,fpList);
    fpList->ClearMap();
    fMapA2->ClearMap();
}
//______________________________________________________________________
void AliITSsimulationSSD::DigitiseModule(AliITSmodule *mod,Int_t,Int_t) {
  // Digitizes hits for one SSD module
  SetModuleNumber(mod->GetIndex());

  HitsToAnalogDigits(mod,fpList);
  SDigitToDigit(GetModuleNumber(),fpList);

  fpList->ClearMap();
  fMapA2->ClearMap();
}
//______________________________________________________________________
void AliITSsimulationSSD::SDigitiseModule(AliITSmodule *mod,Int_t,Int_t) {
  // Produces Summable/Analog digits and writes them to the SDigit tree. 

    HitsToAnalogDigits(mod,fpList);

    WriteSDigits(fpList);

    fpList->ClearMap();
    fMapA2->ClearMap();
}
//______________________________________________________________________
void AliITSsimulationSSD::SDigitToDigit(Int_t module,AliITSpList *pList){
  // Takes the pList and finishes the digitization.

  ApplyNoise(pList,module);
  ApplyCoupling(pList,module);

  ChargeToSignal(pList);
}
//______________________________________________________________________
void AliITSsimulationSSD::HitsToAnalogDigits(AliITSmodule *mod,
                                             AliITSpList *pList){
    // Loops over all hits to produce Analog/floating point digits. This
    // is also the first task in producing standard digits.
    Int_t lasttrack     = -2;
    Int_t idtrack       = -2;
    Double_t x0=0.0, y0=0.0, z0=0.0;
    Double_t x1=0.0, y1=0.0, z1=0.0;
    Double_t de=0.0;
    Int_t module = mod->GetIndex();

    TObjArray *hits = mod->GetHits();
    Int_t nhits     = hits->GetEntriesFast();
    if (nhits<=0) return;
    AliITSTableSSD * tav = new AliITSTableSSD(GetNStrips());
    module = mod->GetIndex();
    if ( mod->GetLayer() == 6 ) GetSegmentation()->SetLayer(6);
    if ( mod->GetLayer() == 5 ) GetSegmentation()->SetLayer(5);
    for(Int_t i=0; i<nhits; i++) {    
        // LineSegmentL returns 0 if the hit is entering
        // If hits is exiting returns positions of entering and exiting hits
        // Returns also energy loss
        if(GetDebug(4)){
            cout << i << " ";
            cout << mod->GetHit(i)->GetXL() << " "<<mod->GetHit(i)->GetYL();
            cout << " " << mod->GetHit(i)->GetZL();
            cout << endl;
        } // end if
        if (mod->LineSegmentL(i, x0, x1, y0, y1, z0, z1, de, idtrack)) {
            HitToDigit(module, x0, y0, z0, x1, y1, z1, de,tav);
            if (lasttrack != idtrack || i==(nhits-1)) {
                GetList(idtrack,i,module,pList,tav);
            } // end if
            lasttrack=idtrack;
        } // end if
    }  // end loop over hits
    delete tav; tav=0;
    return;
}
//----------------------------------------------------------------------
void AliITSsimulationSSD::HitToDigit(Int_t module, Double_t x0, Double_t y0, 
                                     Double_t z0, Double_t x1, Double_t y1, 
                                     Double_t z1, Double_t de,
                                     AliITSTableSSD *tav) {
    // Turns hits in SSD module into one or more digits.
    Float_t tang[2] = {0.0,0.0};
    GetSegmentation()->Angles(tang[0], tang[1]);//stereo<<->tan(stereo)~=stereo
    Double_t x, y, z;
    Double_t dex=0.0, dey=0.0, dez=0.0; 
    Double_t pairs; // pair generation energy per step.
    Double_t sigma[2] = {0.,0.};// standard deviation of the diffusion gaussian
    Double_t tdrift[2] = {0.,0.}; // time of drift
    Double_t w;
    Double_t inf[2], sup[2], par0[2];                 

    // Steps in the module are determined "manually" (i.e. No Geant)
    // NumOfSteps divide path between entering and exiting hits in steps 
    Int_t numOfSteps = NumOfSteps(x1, y1, z1, dex, dey, dez);
    // Enery loss is equally distributed among steps
    de    = de/numOfSteps;
    pairs = de/GetIonizeE(); // e-h pairs generated
    for(Int_t j=0; j<numOfSteps; j++) {     // stepping
        x = x0 + (j+0.5)*dex;
        y = y0 + (j+0.5)*dey;
        if ( y > (GetSegmentation()->Dy()/2+10)*1.0E-4 ) {
            // check if particle is within the detector
            Warning("HitToDigit",
                    "hit out of detector y0=%e,y=%e,dey=%e,j =%e module=%d",
                    y0,y,dey,j,module);
            return;
        } // end if
        z = z0 + (j+0.5)*dez;
        if(GetDebug(4)) cout <<"HitToDigit "<<x<<" "<<y<<" "<<z<< " "
                            <<dex<<" "<<dey<<" "<<dez<<endl;
        // calculate drift time
        // y is the minimum path
        tdrift[0] = (y+(GetSegmentation()->Dy()*1.0E-4)/2)/GetDriftVelocity(0);
        tdrift[1] = ((GetSegmentation()->Dy()*1.0E-4)/2-y)/GetDriftVelocity(1);

        for(Int_t k=0; k<2; k++) {   // both sides    remember: 0=Pside 1=Nside

            tang[k]=TMath::Tan(tang[k]);

            // w is the coord. perpendicular to the strips
            /*
              if(k==0) {
              w = (x+(GetSegmentation()->Dx()*1.0E-4)/2) -
		    (z+(GetSegmentation()->Dz()*1.0E-4)/2)*tang[k]; 
              }else{
              w = (x+(GetSegmentation()->Dx()*1.0E-4)/2) + 
		    (z-(GetSegmentation()->Dz()*1.0E-4)/2)*tang[k];
              } // end if
              w /= (GetStripPitch()*1.0E-4); //w is converted in units of pitch
            */
            { // replacement block for the above.
                Float_t xp=x*1.e+4,zp=z*1.e+4; // microns
                GetSegmentation()->GetPadTxz(xp,zp);
                if(k==0) w = xp; // P side strip number
                else w = zp; // N side strip number
            } // end test block

            if((w<(-0.5)) || (w>(GetNStrips()-0.5))) {
                // this check rejects hits in regions not covered by strips
                // 0.5 takes into account boundaries 
                if(GetDebug(4)) cout << "x,z="<<x<<","<<z<<" w="<<w
                                    <<" Nstrips="<<GetNStrips()<<endl;
                return; // There are dead region on the SSD sensitive volume.
            } // end if

            // sigma is the standard deviation of the diffusion gaussian
            if(tdrift[k]<0) return;
            sigma[k] = TMath::Sqrt(2*GetDiffConst(k)*tdrift[k]);
            sigma[k] /= (GetStripPitch()*1.0E-4);  //units of Pitch
            if(sigma[k]==0.0) { 	
                Error("HitToDigit"," sigma[%d]=0",k);
                exit(0);
            } // end if

            par0[k] = pairs;
            // we integrate the diffusion gaussian from -3sigma to 3sigma 
            inf[k] = w - 3*sigma[k]; // 3 sigma from the gaussian average  
            sup[k] = w + 3*sigma[k]; // 3 sigma from the gaussian average
            // IntegrateGaussian does the actual
            // integration of diffusion gaussian
            IntegrateGaussian(k, par0[k], w, sigma[k], inf[k], sup[k],tav);
        }  // end for loop over side (0=Pside, 1=Nside)      
    } // end stepping
}
//______________________________________________________________________
void AliITSsimulationSSD::ApplyNoise(AliITSpList *pList,Int_t module){
    // Apply Noise.
    Int_t    k,ix;
    Double_t signal,noise;
    Double_t noiseP[2] = {0.,0.};
    Double_t a,b;

    GetResp()->GetNoiseParam(a,b); // retrieves noise parameters
    noiseP[0] = a; noiseP[1] = b;
    for(k=0;k<2;k++){                    // both sides (0=Pside, 1=Nside)
        for(ix=0;ix<GetNStrips();ix++){      // loop over strips
            noise  = gRandom->Gaus(0,noiseP[k]);// get noise to signal
            signal = noise + fMapA2->GetSignal(k,ix);//get signal from map
            if(signal<0.) signal=0.0;           // in case noise is negative...
            fMapA2->SetHit(k,ix,signal); // give back signal to map
            if(signal>0.0) pList->AddNoise(k,ix,module,noise);
        } // loop over strip 
    } // loop over k (P or N side)
}
//______________________________________________________________________
void AliITSsimulationSSD::ApplyCoupling(AliITSpList *pList,Int_t module) {
    // Apply the effect of electronic coupling between channels
    Int_t ix;
    Double_t signalLeft=0, signalRight=0,signal=0;

    for(ix=0;ix<GetNStrips();ix++){
        // P side coupling
        if(ix>0.)signalLeft = fMapA2->GetSignal(0,ix-1)*fDCS->GetCouplingPL();
        else signalLeft = 0.0;
        if(ix<(GetNStrips()-1)) signalRight = fMapA2->GetSignal(0,ix+1)*
                                    fDCS->GetCouplingPR();
        else signalRight = 0.0;
        signal = signalLeft + signalRight;
        fMapA2->AddSignal(0,ix,signal);
        if(signal>0.0) pList->AddNoise(0,ix,module,signal);

        signalLeft = signalRight = signal = 0.0;
        // N side coupling
        if(ix>0.) signalLeft = fMapA2->GetSignal(1,ix-1)*fDCS->GetCouplingNL();
        else signalLeft = 0.0;
        if(ix<(GetNStrips()-1)) signalRight = fMapA2->GetSignal(1,ix+1)*
                                    fDCS->GetCouplingNR();
        else signalRight = 0.0;
        signal = signalLeft + signalRight;
        fMapA2->AddSignal(1,ix,signal);
        if(signal>0.0) pList->AddNoise(1,ix,module,signal);
    } // loop over strips 
}
//______________________________________________________________________
Float_t AliITSsimulationSSD::F(Float_t av, Float_t x, Float_t s) {
    // Computes the integral of a gaussian using Error Function
    Float_t sqrt2 = TMath::Sqrt(2.0);
    Float_t sigm2 = sqrt2*s;
    Float_t integral;

    integral = 0.5 * TMath::Erf( (x - av) / sigm2);
    return integral;
}
//______________________________________________________________________
void AliITSsimulationSSD::IntegrateGaussian(Int_t k,Double_t par, Double_t w,
                                            Double_t sigma, 
                                            Double_t inf, Double_t sup,
                                            AliITSTableSSD *tav) {
    // integrate the diffusion gaussian
    // remind: inf and sup are w-3sigma and w+3sigma
    //         we could define them here instead of passing them
    //         this way we are free to introduce asimmetry

    Double_t a=0.0, b=0.0;
    Double_t dXCharge1 = 0.0, dXCharge2 = 0.0;
    // dXCharge1 and 2 are the charge to two neighbouring strips
    // Watch that we only involve at least two strips
    // Numbers greater than 2 of strips in a cluster depend on
    //  geometry of the track and delta rays, not charge diffusion!   

    Double_t strip = TMath::Floor(w);         // closest strip on the left

    if ( TMath::Abs((strip - w)) < 0.5) { 
        // gaussian mean is closer to strip on the left
        a = inf;                         // integration starting point
        if((strip+0.5)<=sup) {
            // this means that the tail of the gaussian goes beyond
            // the middle point between strips ---> part of the signal
            // is given to the strip on the right
            b = strip + 0.5;               // integration stopping point
            dXCharge1 = F( w, b, sigma) - F(w, a, sigma);
            dXCharge2 = F( w, sup, sigma) - F(w ,b, sigma); 
        }else { 
            // this means that all the charge is given to the strip on the left
            b = sup;
            dXCharge1 = 0.9973;   // gaussian integral at 3 sigmas
            dXCharge2 = 0.0;
        } // end if
        dXCharge1 = par * dXCharge1;// normalize by mean of number of carriers
        dXCharge2 = par * dXCharge2;

        // for the time being, signal is the charge
        // in ChargeToSignal signal is converted in ADC channel
        fMapA2->AddSignal(k,(Int_t)strip,dXCharge1);
        tav->Add(k,(Int_t)strip);
        if(((Int_t) strip) < (GetNStrips()-1)) {
            // strip doesn't have to be the last (remind: last=GetNStrips()-1)
            // otherwise part of the charge is lost
            fMapA2->AddSignal(k,((Int_t)strip+1),dXCharge2);
            tav->Add(k,((Int_t)(strip+1)));
        } // end if
    }else{
        // gaussian mean is closer to strip on the right
        strip++;     // move to strip on the rigth
        b = sup;     // now you know where to stop integrating
        if((strip-0.5)>=inf) { 
            // tail of diffusion gaussian on the left goes left of
            // middle point between strips
            a = strip - 0.5;        // integration starting point
            dXCharge1 = F(w, b, sigma) - F(w, a, sigma);
            dXCharge2 = F(w, a, sigma) - F(w, inf, sigma);
        }else {
            a = inf;
            dXCharge1 = 0.9973;   // gaussian integral at 3 sigmas
            dXCharge2 = 0.0;
        } // end if
        dXCharge1 = par * dXCharge1;    // normalize by means of carriers
        dXCharge2 = par * dXCharge2;
        // for the time being, signal is the charge
        // in ChargeToSignal signal is converted in ADC channel
        fMapA2->AddSignal(k,(Int_t)strip,dXCharge1);
        tav->Add(k,(Int_t)strip);
        if(((Int_t) strip) > 0) {
            // strip doesn't have to be the first
            // otherwise part of the charge is lost
            fMapA2->AddSignal(k,((Int_t)strip-1),dXCharge2);
            tav->Add(k,((Int_t)(strip-1)));
        } // end if
    } // end if
}
//______________________________________________________________________
Int_t AliITSsimulationSSD::NumOfSteps(Double_t x, Double_t y, Double_t z,
                                      Double_t &dex,Double_t &dey,
                                      Double_t &dez){
    // number of steps
    // it also returns steps for each coord
    //AliITSsegmentationSSD *seg = new AliITSsegmentationSSD();

    Double_t step = 25E-4;
    //step = (Double_t) seg->GetStepSize();  // step size (cm)
    Int_t numOfSteps = (Int_t) (TMath::Sqrt(x*x+y*y+z*z)/step); 

    if (numOfSteps < 1) numOfSteps = 1;       // one step, at least

    // we could condition the stepping depending on the incident angle
    // of the track
    dex = x/numOfSteps;
    dey = y/numOfSteps;
    dez = z/numOfSteps;
    
    return numOfSteps;
}
//----------------------------------------------------------------------
void AliITSsimulationSSD::GetList(Int_t label,Int_t hit,Int_t mod,
                                  AliITSpList *pList,AliITSTableSSD *tav) {
    // loop over nonzero digits
    Int_t ix,i;
    Double_t signal=0.;

    for(Int_t k=0; k<2; k++) {
        ix=tav->Use(k);
        while(ix>-1){
            signal = fMapA2->GetSignal(k,ix);
            if(signal==0.0) {
                ix=tav->Use(k);
                continue;
            } // end if signal==0.0
            // check the signal magnitude
            for(i=0;i<pList->GetNSignals(k,ix);i++){
                signal -= pList->GetTSignal(k,ix,i);
            } // end for i
            //  compare the new signal with already existing list
            if(signal>0)pList->AddSignal(k,ix,label,hit,mod,signal);
            ix=tav->Use(k);
        } // end of loop on strips
    } // end of loop on P/N side
    tav->Clear();
}
//----------------------------------------------------------------------
void AliITSsimulationSSD::ChargeToSignal(AliITSpList *pList) {
    // charge to signal
    static AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");
    Float_t threshold = 0.;
    Int_t size = AliITSdigitSSD::GetNTracks();
    Int_t * digits = new Int_t[size];
    Int_t * tracks = new Int_t[size];
    Int_t * hits = new Int_t[size];
    Int_t j1;
    Float_t charges[3] = {0.0,0.0,0.0};
    Float_t signal;
    Double_t noise[2] = {0.,0.};

    GetResp()->GetNoiseParam(noise[0],noise[1]);

    for(Int_t k=0;k<2;k++){         // both sides (0=Pside, 1=Nside)
        // Threshold for zero-suppression
        // It can be defined in AliITSresponseSSD
        //             threshold = (Float_t)GetResp()->MinVal(k);
        // I prefer to think adjusting the threshold "manually", looking
        // at the scope, and considering noise standard deviation
        threshold = 4.0*noise[k]; // 4 times noise is a choice
        for(Int_t ix=0;ix<GetNStrips();ix++){     // loop over strips
            if(fMapA2->GetSignal(k,ix) <= threshold)continue;
            // convert to ADC signal
            signal = GetResp()->DEvToADC(
                fMapA2->GetSignal(k,ix));
            if(signal>1024.) signal = 1024.;//if exceeding, accumulate last one
            digits[0] = k;
            digits[1] = ix;
            digits[2] = (Int_t) signal;
            for(j1=0;j1<size;j1++)if(j1<pList->GetNEnteries()){
                // only three in digit.
                tracks[j1]  = pList->GetTrack(k,ix,j1);
                hits[j1]    = pList->GetHit(k,ix,j1);
            }else{
                tracks[j1]  = -3;
                hits[j1]    = -1;
            } // end for j1
            // finally add digit
            aliITS->AddSimDigit(2,0,digits,tracks,hits,charges);
        } // end for ix
    } // end for k
    delete [] digits;
    delete [] tracks;
    delete [] hits;
}
//______________________________________________________________________
void AliITSsimulationSSD::WriteSDigits(AliITSpList *pList){
    // Fills the Summable digits Tree
    Int_t i,ni,j,nj;
    static AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");

    pList->GetMaxMapIndex(ni,nj);
    for(i=0;i<ni;i++)for(j=0;j<nj;j++){
        if(pList->GetSignalOnly(i,j)>0.0){
            aliITS->AddSumDigit(*(pList->GetpListItem(i,j)));
            if(GetDebug(4)) cout << "pListSSD: "<<*(pList->GetpListItem(i,j))
                                << endl;
        } // end if
    } // end for i,j
  return;
}
//______________________________________________________________________
void AliITSsimulationSSD::FillMapFrompList(AliITSpList *pList){
    // Fills fMap2A from the pList of Summable digits
    Int_t k,ix;

    for(k=0;k<2;k++)for(ix=0;ix<GetNStrips();ix++) 
        fMapA2->AddSignal(k,ix,pList->GetSignal(k,ix));
    return;
}
//______________________________________________________________________
void AliITSsimulationSSD::Print(ostream *os){
    //Standard output format for this class

    //AliITSsimulation::Print(os);
    *os << fIonE <<",";
    *os << fDifConst[0] <<","<< fDifConst[1] <<",";
    *os << fDriftVel[0] <<","<< fDriftVel[1];
    //*os <<","; fDCS->Print(os);
    //*os <<","; fMapA2->Print(os);
}
//______________________________________________________________________
void AliITSsimulationSSD::Read(istream *is){
    // Standard output streaming function.

    //AliITSsimulation::Read(is);
    *is >> fIonE;
    *is >> fDifConst[0] >> fDifConst[1];
    *is >> fDriftVel[0] >> fDriftVel[1];
    //fDCS->Read(is);
    //fMapA2->Read(is);
}
//______________________________________________________________________
ostream &operator<<(ostream &os,AliITSsimulationSSD &source){
    // Standard output streaming function.

    source.Print(&os);
    return os;
}
//______________________________________________________________________
istream &operator>>(istream &os,AliITSsimulationSSD &source){
    // Standard output streaming function.

    source.Read(&os);
    return os;
}
//______________________________________________________________________