Cosmetic changes.

[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 <iostream.h>
#include <iomanip.h>
#include <TObjArray.h>
#include <TRandom.h>
#include <TMath.h>

#include "AliITSmodule.h"
#include "AliITSMapA2.h"
#include "AliITSsegmentationSSD.h"
#include "AliITSresponseSSD.h"
#include "AliITSdcsSSD.h"
#include "AliITS.h"
#include "AliRun.h"
#include "AliITSgeom.h"
#include "AliITSsimulationSSD.h"

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

//----------------------------------------------------------------------
AliITSsimulationSSD::AliITSsimulationSSD(){
    //default Constructor

    fDCS     = 0;
    fNstrips = GetSegmentation()->Npx();
    fPitch   = GetSegmentation()->Dpx(0);
    fDifConst[0] = fDifConst[1] = 0.0;
    fDriftVel[0] = fDriftVel[1] = 0.0;
    fMapA2   = 0;
}
//----------------------------------------------------------------------
AliITSsimulationSSD::AliITSsimulationSSD(AliITSsegmentation *seg,
                                         AliITSresponse *resp){
    // Constructor

    fSegmentation    = seg;
    fResponse        = resp;
    Float_t noise[2] = {0.,0.};
    fResponse->GetNoiseParam(noise[0],noise[1]); // retrieves noise parameters
    fDCS             = new AliITSdcsSSD(seg,resp); 

    fNstrips         = GetSegmentation()->Npx();
    fPitch           = GetSegmentation()->Dpx(0);
    SetDriftVelocity(); // use default values in .h file
    SetIonizeE();       // use default values in .h file
    SetDiffConst();     // use default values in .h file
    fMapA2           = new AliITSMapA2(fSegmentation);
}
//______________________________________________________________________
AliITSsimulationSSD& AliITSsimulationSSD::operator=(
                                                const AliITSsimulationSSD &s){
    // Operator =

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

    this->fDCS         = new AliITSdcsSSD(*(s.fDCS));
    this->fMapA2       = s.fMapA2;
    this->fNstrips     = s.fNstrips;
    this->fPitch       = s.fPitch;
    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(const AliITSsimulationSSD &source){
    // copy constructor

    *this = source;
}
//______________________________________________________________________
AliITSsimulationSSD::~AliITSsimulationSSD() {
    // destructor
    delete fMapA2;
    delete fDCS;
}
//______________________________________________________________________
void AliITSsimulationSSD::DigitiseModule(AliITSmodule *mod,Int_t module,
                                         Int_t dummy) {
    // Digitizes hits for one SSD module 

    Int_t lay, lad, detect;
    AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");
    AliITSgeom *geom = aliITS->GetITSgeom();
    geom->GetModuleId(module,lay, lad, detect);
    if ( lay == 6 ) GetSegmentation()->SetLayer(6);
    if ( lay == 5 ) GetSegmentation()->SetLayer(5);

    TObjArray *hits = mod->GetHits();
    Int_t nhits     = hits->GetEntriesFast();
    if (!nhits) return;
  
    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 maxNdigits = 2*fNstrips;
    Float_t  **pList = new Float_t* [maxNdigits]; 
    memset(pList,0,sizeof(Float_t*)*maxNdigits);
    Int_t indexRange[4] = {0,0,0,0};
    static Bool_t first = kTRUE;
    Int_t lasttrack     = -2;
    Int_t idtrack       = -2;
    
    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 (mod->LineSegmentL(i, x0, x1, y0, y1, z0, z1, de, idtrack)) {
	    HitToDigit(module, x0, y0, z0, x1, y1, z1, de, indexRange, first);
       
	    if (lasttrack != idtrack || i==(nhits-1)) {
		GetList(idtrack,pList,indexRange);
		first=kTRUE;
	    } // end if
	    lasttrack=idtrack;
	} // end if
    }  // end loop over hits
  
    ApplyNoise();
    ApplyCoupling();

    ChargeToSignal(pList);

    fMapA2->ClearMap();
}
//----------------------------------------------------------------------
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,
				     Int_t *indexRange, Bool_t first) {
    // 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
	    cout<<"AliITSsimulationSSD::HitToDigit: Warning: hit "
		"out of detector y0,y,dey,j ="
		<<y0<<","<<y<<","<<dey<<","<<j<<endl;
	    return;
	} // end if
	z = z0 + (j+0.5)*dez;

	// 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 = w / (fPitch*1.0E-4); // w is converted in units of pitch

	    if((w<(-0.5)) || (w>(fNstrips-0.5))) {
		// this check rejects hits in regions not covered by strips
		// 0.5 takes into account boundaries 
		if(k==0) cout<<"AliITSsimulationSSD::HitToDigit: "
			     "Warning: no strip in this region of P side"
			     <<endl;
		else cout<<"AliITSsimulationSSD::HitToDigit: "
			 "Warning: no strip in this region of N side"<<endl;
		return;
	    } // 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] = sigma[k] /(fPitch*1.0E-4);  //units of Pitch
	    if(sigma[k]==0.0) { 	
		cout<<"AliITSsimulationSSD::DigitiseModule: Error: sigma=0"
		    <<endl; 
		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], 
			      indexRange, first);
	}  // end for loop over side (0=Pside, 1=Nside)      
    } // end stepping
    //delete seg;
}
//______________________________________________________________________
void AliITSsimulationSSD::ApplyNoise() {
    // Apply Noise.
  
    Double_t signal;
    Double_t noise[2] = {0.,0.};
    Float_t a,b;
    fResponse->GetNoiseParam(a,b); // retrieves noise parameters
    noise[0] = (Double_t) a; noise[1] = (Double_t) b;
    for(Int_t k=0;k<2;k++){                    // both sides (0=Pside, 1=Nside)
	for(Int_t ix=0;ix<fNstrips;ix++){      // loop over strips
	    signal = fMapA2->GetSignal(k,ix); // retrieves signal from map
	    signal += gRandom->Gaus(0,noise[k]);// add noise to signal
	    if(signal<0.) signal=0.0;           // in case noise is negative...
	    fMapA2->SetHit(k,ix,signal); // give back signal to map
	} // loop over strip 
    } // loop over k (P or N side)
}
//______________________________________________________________________
void AliITSsimulationSSD::ApplyCoupling() {
    // Apply the effect of electronic coupling between channels
    Double_t signalLeft=0, signalRight=0;

    for(Int_t ix=0;ix<fNstrips;ix++){
	if(ix>0.)signalLeft = fMapA2->GetSignal(0,ix-1)*fDCS->GetCouplingPL();
	else signalLeft = 0.0;
	if(ix<(fNstrips-1)) signalRight = fMapA2->GetSignal(0,ix+1)*
                                                        fDCS->GetCouplingPR();
	else signalRight = 0.0;
	fMapA2->AddSignal(0,ix,signalLeft + signalRight);
    
	if(ix>0.) signalLeft = fMapA2->GetSignal(1,ix-1)*fDCS->GetCouplingNL();
	else signalLeft = 0.0;
	if(ix<(fNstrips-1)) signalRight = fMapA2->GetSignal(1,ix+1)*
                                                         fDCS->GetCouplingNR();
	else signalRight = 0.0;
	fMapA2->AddSignal(1,ix,signalLeft + signalRight);
    } // 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,
					    Int_t *indexRange, Bool_t first) {
    // 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);         // clostest 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,strip,dXCharge1);
	if(((Int_t) strip) < (fNstrips-1)) {
	    // strip doesn't have to be the last (remind: last=fNstrips-1)
	    // otherwise part of the charge is lost
	    fMapA2->AddSignal(k,(strip+1),dXCharge2);
	} // end if
    
	if(dXCharge1 > 1.) {
	    if (first) {
		indexRange[k*2+0] = indexRange[k*2+1]=(Int_t) strip;
		first=kFALSE;
	    } // end if first

	    indexRange[k*2+0]=TMath::Min(indexRange[k*2+0],(Int_t) strip);
	    indexRange[k*2+1]=TMath::Max(indexRange[k*2+1],(Int_t) strip);
	}      // dXCharge > 1 e-

    }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,strip,dXCharge1);
	if(((Int_t) strip) > 0) {
	    // strip doesn't have to be the first
	    // otherwise part of the charge is lost
	    fMapA2->AddSignal(k,(strip-1),dXCharge2);
	} // end if
    
	if(dXCharge1 > 1.) {
	    if (first) {
		indexRange[k*2+0]=indexRange[k*2+1]=(Int_t) strip;
		first=kFALSE;
	    } // end if first

	    indexRange[k*2+0]=TMath::Min(indexRange[k*2+0],(Int_t) strip);
	    indexRange[k*2+1]=TMath::Max(indexRange[k*2+1],(Int_t) strip);
	}      // dXCharge > 1 e-
    } // 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,Float_t **pList,
				  Int_t *indexRange) {
    // loop over nonzero digits
    Int_t ix,globalIndex;
    Float_t signal=0.;
    Float_t highest,middle,lowest;

    for(Int_t k=0; k<2; k++) {
	for(ix=indexRange[k*2+0];ix<indexRange[k*2+1]+1;ix++){
	    if(indexRange[k*2+0]<indexRange[k*2+1]) 
		signal = fMapA2->GetSignal(k,ix);

	    globalIndex = k*fNstrips+ix; // globalIndex starts from 0!
	    if(!pList[globalIndex]){
		// 
		//Create new list (6 elements-3 signals and 3 tracks+total sig)
		//
		pList[globalIndex] = new Float_t [6];
		// set list to -1
		*pList[globalIndex] = -2.;
		*(pList[globalIndex]+1) = -2.;
		*(pList[globalIndex]+2) = -2.;
		*(pList[globalIndex]+3) =  0.;
		*(pList[globalIndex]+4) =  0.;
		*(pList[globalIndex]+5) =  0.;
		*pList[globalIndex] = (float)label;
		*(pList[globalIndex]+3) = signal;
	    }else{
		// check the signal magnitude
		highest = *(pList[globalIndex]+3);
		middle = *(pList[globalIndex]+4);
		lowest = *(pList[globalIndex]+5);
		signal -= (highest+middle+lowest);
		//
		//  compare the new signal with already existing list
		//
		if(signal<lowest) continue; // neglect this track
		if (signal>highest){
		    *(pList[globalIndex]+5) = middle;
		    *(pList[globalIndex]+4) = highest;
		    *(pList[globalIndex]+3) = signal;
		    *(pList[globalIndex]+2) = *(pList[globalIndex]+1);
		    *(pList[globalIndex]+1) = *pList[globalIndex];
		    *pList[globalIndex] = label;
		}else if (signal>middle){
		    *(pList[globalIndex]+5) = middle;
		    *(pList[globalIndex]+4) = signal;
		    *(pList[globalIndex]+2) = *(pList[globalIndex]+1);
		    *(pList[globalIndex]+1) = label;
		}else{
		    *(pList[globalIndex]+5) = signal;
		    *(pList[globalIndex]+2) = label;
		} // end if
	    } // end if
	} // end of loop pixels in x
    } // end of loop over pixels in z
}
//----------------------------------------------------------------------
void AliITSsimulationSSD::ChargeToSignal(Float_t **pList) {
    // charge to signal
    AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");
    Float_t threshold = 0.;
    Int_t digits[3], tracks[3],hits[3],gi,j1;
    Float_t charges[3];
    Float_t signal,phys;
    Float_t noise[2] = {0.,0.};

    fResponse->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)fResponse->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<fNstrips;ix++){         // loop over strips

	    signal = (Float_t) fMapA2->GetSignal(k,ix);
	    gi =k*fNstrips+ix; // global index
	    if (signal > threshold) {
		digits[0]=k;
		digits[1]=ix;

		// convert to ADC signal
		// conversion factor are rather arbitrary (need tuning)
		// minimum ionizing particle--> ~30000 pairs--> ADC channel 50
		signal = signal*50.0/30000.0;        
		if(signal>1000.) signal = 1000.0;//if exceeding, accumulate
                                                 // last one
		digits[2]=(Int_t) signal;
		for(j1=0;j1<3;j1++){
		    if (pList[gi]) {
			tracks[j1] = (Int_t)(*(pList[gi]+j1));
		    } else {
			tracks[j1]=-2; //noise
		    } // end if pList
		    charges[j1] = 0;
		} // end for j1

		phys=0;

		hits[0]=0;
		hits[1]=0;
		hits[2]=0;
		// finally add digit
		aliITS->AddSimDigit(2,phys,digits,tracks,hits,charges);
	    } // end if signal > threshold
	    if(pList[gi]) delete [] pList[gi];
	} // end for ix
    } // end for k
    delete [] pList;
}
//______________________________________________________________________
void AliITSsimulationSSD::Print(ostream *os){
    //Standard output format for this class

    //AliITSsimulation::Print(os);
    *os << fNstrips <<","<< fPitch <<","<< 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 >> fNstrips >> fPitch >> 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;
}