PndSdsCalcStrip.cxx

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//______________________________________________________________________________
//
// C++ Implementation: PndSdsCalcStrip
//
// Description: 
//
//
// Author: HG Zaunick <hg.zaunick@physik.tu-dresden.de>, (C) 2007
//
// Copyright: See COPYING file that comes with this distribution
//
//
#include <cmath>
#include <exception>

#include "PndSdsCalcStrip.h"
#include "TRandom.h"

//______________________________________________________________________________
PndSdsCalcStrip::PndSdsCalcStrip() :
    fPitch(0.),
    fOrient(0.),
    fNrStrips(0),
    fNrFeChannels(0),
    fAnchor(0.,0.),
    fThreshold(0.),
    fNoise(0.),
    fCSigma(0.),
    fStripDir(0.,0.),
    fOrthoDir(0.,0.),
    fVerboseLevel(0)
{}

//______________________________________________________________________________
PndSdsCalcStrip::PndSdsCalcStrip(Double_t pitch, Double_t orient,
                                 Int_t nrStrips, Int_t nrFeChannels,
                                 const TVector2& firstStripAnchor,
                                 Double_t threshold, Double_t noise, Double_t csigma=0)
: fPitch(pitch), fOrient(orient),
fNrStrips(nrStrips), fNrFeChannels(nrFeChannels),
fAnchor(firstStripAnchor),
fThreshold(threshold), fNoise(noise), fCSigma(csigma),  
fStripDir(0.,0.),    fOrthoDir(0.,0.),    fVerboseLevel(0)
{
  fStripDir.Set(cos(fOrient),sin(fOrient));
  fOrthoDir.Set(sin(fOrient),-cos(fOrient));
  //Print();
}

//______________________________________________________________________________
PndSdsCalcStrip::PndSdsCalcStrip(const PndSdsStripDigiPar* digipar, SensorSide side)
:   fPitch(0.),
    fOrient(0.),
    fNrStrips(0),
    fNrFeChannels(0),
    fAnchor(0.,0.),
    fThreshold(0.),
    fNoise(0.),
    fCSigma(0.),
    fStripDir(0.,0.),
    fOrthoDir(0.,0.),
    fVerboseLevel(0)
{
  if(side == kTOP)
  {
    fPitch = digipar->GetTopPitch();
    fOrient = digipar->GetOrient();
    fAnchor = digipar->GetTopAnchor();
    fNrStrips = digipar->GetNrTopFE()*digipar->GetNrFECh();
  }
  else if(side == kBOTTOM)
  {
    fPitch = digipar->GetBotPitch();
    fOrient = digipar->GetOrient() + digipar->GetSkew();
    fAnchor = digipar->GetBotAnchor();
    fNrStrips = digipar->GetNrBotFE()*digipar->GetNrFECh();
  }
  fNrFeChannels = digipar->GetNrFECh();
  fThreshold = digipar->GetThreshold();
  fNoise = digipar->GetNoise();
  fCSigma = digipar->GetQCloudSigma();
  
  fStripDir.Set(cos(fOrient),sin(fOrient));
  fOrthoDir.Set(sin(fOrient),-cos(fOrient));
  fVerboseLevel = 0;
  if (fVerboseLevel > 0) Print();
}


//______________________________________________________________________________
std::vector<PndSdsStrip>
PndSdsCalcStrip::GetStrips(Double_t inx, Double_t iny, Double_t ,   //inz //[R.K.03/2017] unused variable(s)
                           Double_t outx, Double_t outy, Double_t ,  //  outz //[R.K.03/2017] unused variable(s)
                           Double_t eLoss)
{
  if (fVerboseLevel > 2) std::cout<<"-I- PndSdsCalcStrip::GetStrips "<<std::endl;
  
  // 2d-Projection of trajectory
  TVector2 in(inx,iny);
  TVector2 out(outx,outy);
  TVector2 path=out-in;
  
  if (fVerboseLevel > 2){
    std::cout<<" InPoint: ("<<in.X()<<","<<in.Y()<<")"<<std::endl;
    std::cout<<" OutPoint: ("<<out.X()<<","<<out.Y()<<")"<<std::endl;
  }
  
  //if (path.Mod()<1E-18) {
  //std::cout<<"-W- PndSdsCalcStrip::GetStrips : No Trajectory inside Sensor! (out-in).Mod() = "<<path.Mod()<<std::endl;
  //std::vector<PndSdsStrip> strips;
  //return strips;
  //}    
  
  if (fVerboseLevel > 1) std::cout<<" pathlength: "<<path.Mod()<<std::endl;
  
  Double_t nuIn  = CalcStripFromPoint(inx,iny);
  Double_t nuOut = CalcStripFromPoint(outx,outy);
  
  if (fVerboseLevel > 2) std::cout<<" nuIn = "<<nuIn<<" ; nuOut = "<<nuOut<<std::endl;
  
  Double_t Q = ChargeFromEloss(eLoss);//*1E9/3.61; // 3.6 eV/Electron in Silicon
  if (fVerboseLevel > 1) std::cout<<" integral charge = "<<Q<<std::endl;
  if (fVerboseLevel > 1) std::cout<<"Charge cloud sigma="<<fCSigma<<std::endl;
  // Do charge distribution
  if(fCSigma>0) return GetStripsDif(nuIn,nuOut,Q);
  else          return GetStripsNoDif(nuIn,nuOut,Q);
  
}


//______________________________________________________________________________
std::vector<PndSdsStrip> PndSdsCalcStrip::GetStripsNoDif(Double_t nuIn, Double_t nuOut, Double_t Q)
{
  // Charge distributed equally along a path.
  
  if (fVerboseLevel > 2) std::cout<<"-I- PndSdsCalcStrip::GetStripsNoDif "<<std::endl;
  std::vector<PndSdsStrip> strips;
  
  if (fVerboseLevel > 2) std::cout<<" nuIn = "<<nuIn<<" ; nuOut = "<<nuOut<<std::endl;
  if (fVerboseLevel > 1) std::cout<<" integral charge = "<<Q<<std::endl;
  
  // did we hit the active area ?
  //     if ( (nuIn<0.5 && nuOut<0.5) || (((nuIn+0.5) > Double_t(fNrStrips-1)) && ((nuOut+0.5) > Double_t(fNrStrips-1)))){
  if ( (nuIn<0. && nuOut<0.) || ((nuIn > Double_t(fNrStrips)) && (nuOut > Double_t(fNrStrips))) )
  {
    if (fVerboseLevel > 1) std::cout<<"-W- PndSdsCalcStrip::GetStripsNoDif: Hit outside active area."<<std::endl;
    return strips;
  }
  
  // is the In-Point inside active area ? 
  // only charge fraction inside active area taken
  if (nuIn<0.){
    Q *= (nuOut)/(nuOut-nuIn);
    nuIn = 0.;
  } else if (nuIn > (Double_t(fNrStrips))){
    Q *= ((Double_t)fNrStrips-nuOut)/(-nuOut+nuIn);
    nuIn = Double_t(fNrStrips);
  }
  
  // is the Out-Point inside active area ?
  if (nuOut<0.){
    Q *= (nuIn)/(-nuOut+nuIn);
    nuOut = 0.;
  } else if (nuOut > (Double_t(fNrStrips))){
    Q *= ((Double_t)fNrStrips-nuIn)/(nuOut-nuIn);
    nuOut = Double_t(fNrStrips);
  }
  
  // only one strip hit ?
  if (Int_t(nuIn) == Int_t(nuOut)){
    // this strip collected the entire charge
    InjectStripCharge(strips,(Int_t)nuOut,Q);
    return strips;
    
  } else 
  { // more than one strip is hit
    Double_t dQ=Q/std::fabs(nuOut-nuIn);
    Double_t dir = (nuOut>nuIn) ? 1. : -1.;
    Int_t nrHits = 0;
    
    // calculate portion of track in first strip
    Int_t nextIn = Int_t(nuIn + 0.5+0.5*dir);
    Double_t Q1 = dQ*std::fabs(nextIn-nuIn);
    if (fVerboseLevel > 2){
      std::cout<<" part of first strip : "<<nextIn-nuIn<<std::endl ;
      std::cout<<" charge : "<<Q1<<std::endl ;
      std::cout<<" next strip : "<<nextIn<<std::endl ;
    }              
    InjectStripCharge(strips,(Int_t)nuIn,Q1);
    nrHits++;
    Q -= Q1;
    
    // calculate portion of track in last strip
    Int_t prevOut = Int_t(nuOut + 0.5-0.5*dir);
    Double_t Q2 = dQ*std::fabs(nuOut-prevOut);
    if (fVerboseLevel > 2){
      std::cout<<" part of last strip : "<<(nuOut-prevOut)<<std::endl ;
      std::cout<<" charge : "<<Q2<<std::endl ;
      std::cout<<" end of previous strip : "<<prevOut<<std::endl ;
    }  
    InjectStripCharge(strips,(Int_t)nuOut,Q2);
    nrHits++;
    Q -= Q2;
    
    // Distribute the charge amongst the intermediate strips
    nextIn = Int_t(nextIn - 0.5 + 0.5*dir);
    prevOut = Int_t(prevOut - 0.5 + 0.5*dir);
    if (fVerboseLevel > 2) {
      std::cout<<" dir="<<Int_t(dir)<<std::endl;
      std::cout<<" begin="<<nextIn<<" end="<<prevOut<<std::endl;
    }
    
    for (Int_t n = nextIn ; n != prevOut; n += Int_t(dir) )
    {
      if (fVerboseLevel > 2) std::cout<<" n = "<<n<<std::endl;
      InjectStripCharge(strips,n,dQ);
      nrHits++;
      Q -= dQ;
    }
    if (fVerboseLevel > 2) if (fabs(Q)>1.) std::cout<<" charge Q = "<<Q<<" not detected!"<<std::endl;
    if (fVerboseLevel > 1) std::cout<<" -> "<<nrHits<<" strips hit."<<std::endl;
  }
  
  return strips;
}

//______________________________________________________________________________
std::vector<PndSdsStrip> PndSdsCalcStrip::GetStripsDif(Double_t pathstart, Double_t pathend, Double_t Q)
{
  // Do charge diffusion integrated analytically over a path length
  // 0.5*(1+erf(x)) is the integral over a gauss from -inf to x
  // factor 0.5 is applied last, the +1 terms cancel in the difference
  
  if(pathend<pathstart){ // sort for direction
    Double_t tmp=pathstart;
    pathstart=pathend;
    pathend=tmp;
  }  
  std::vector<PndSdsStrip> array;
        Double_t DQ = 0.;
  // sigma_str = sigma_um/pitch_str-per-um
  Double_t sigma_str=fCSigma/fPitch;
  // TODO how much extra bins to fill?, minimum 1...
  // how about 2sigma? shall be collected
  Int_t xtra = (Int_t)ceil(2.*sigma_str);
  for(Int_t i=(Int_t)pathstart-xtra;i<(Int_t)pathend+1+xtra;i++)
  {
    DQ=0;
    if(fabs(pathstart-pathend) < 1e-6) { // too small path, don't integrate over path
      DQ+=TMath::Erf(i+1-0.5*(pathstart+pathend))/(sqrt(2)*sigma_str);
      DQ-=TMath::Erf(i-0.5*(pathstart+pathend))/(sqrt(2)*sigma_str);
    } else {
      DQ+=CalcFk(i,pathend,sigma_str);
      DQ-=CalcFk(i+1,pathend,sigma_str);
      DQ-=CalcFk(i,pathstart,sigma_str);
      DQ+=CalcFk(i+1,pathstart,sigma_str);
      DQ/=(pathend-pathstart);
    }
    DQ*=0.5*Q;
    InjectStripCharge(array,i,DQ);
  }
  return array;
}

//______________________________________________________________________________
Double_t PndSdsCalcStrip::CalcFk(Double_t strip, Double_t x, Double_t sig)
{
  const Double_t t=(strip-x)/(sqrt(2)*sig);
  return ( (strip-x)*TMath::Erf(t) + sqrt(2/TMath::Pi())*sig*exp(-t*t) );
}

//______________________________________________________________________________
Int_t PndSdsCalcStrip::GetStripsAlternative(Double_t nuIn, Double_t nuOut, Double_t Q, Int_t mode, std::vector<Int_t>& indice, std::vector<Double_t>& charges)
{
  if(fVerboseLevel>2)Info("GetStripsAlternative()","begin with in=%f, out=%f, Q=%f",nuIn,nuOut,Q);
  std::vector<PndSdsStrip> strips;
  if(mode == 0) strips = GetStripsNoDif(nuIn,nuOut,Q);
  if(mode == 1) strips = GetStripsDif(nuIn,nuOut,Q);  
  Int_t nstr=strips.size();
  for(Int_t i=0;i<nstr;i++)
  { 
    if(fVerboseLevel>2) Info("GetStripsAlternative()","pass this strip: i=%i, s=%i, q=%f",i,strips[i].GetIndex(),strips[i].GetCharge());
    indice.push_back(strips[i].GetIndex());
    charges.push_back(strips[i].GetCharge());
  }
  return nstr;
}

//______________________________________________________________________________
Double_t PndSdsCalcStrip::CalcStripFromPoint(Double_t x, Double_t y)
{
  // fOrthoDir is already set to magnitude == 1., makes it cheaper here.
  return ((x-fAnchor.X())*fOrthoDir.X() + (y-fAnchor.Y())*fOrthoDir.Y())/fPitch;
}

//______________________________________________________________________________
void PndSdsCalcStrip::CalcStripPointOnLine(Double_t strip,TVector2& point) const
{
  point = fPitch*(strip+0.5)*fOrthoDir + fAnchor;
}

//______________________________________________________________________________
Int_t PndSdsCalcStrip::CalcFEfromStrip(Int_t stripNr) const { return (stripNr/fNrFeChannels); }

//______________________________________________________________________________
Int_t PndSdsCalcStrip::CalcChannelfromStrip(Int_t stripNr) const { return (stripNr%fNrFeChannels); }

//______________________________________________________________________________
void PndSdsCalcStrip::CalcFeChToStrip(Int_t fe, Int_t channel, Int_t& strip, enum SensorSide& side) const
{
  //Caution! The top side s always the reference side!
  Int_t nr = fe * fNrFeChannels + channel;
  if (nr < fNrStrips) {
    side = kTOP;
  } else {
    nr -= fNrStrips;
    side = kBOTTOM;
  }
  strip = nr;
}

//______________________________________________________________________________
void PndSdsCalcStrip::InjectStripCharge(std::vector<PndSdsStrip>& array, Int_t istrip, Double_t charge)
{
  if(istrip<0) {if(fVerboseLevel>2)Warning("InjectStripCharge","Invalid strip number: %i < 0",istrip); return;}
  if(istrip>fNrStrips) {if(fVerboseLevel>2)Warning("InjectStripCharge","Invalid strip number: %i > %i",istrip,fNrStrips); return;}
  if(charge==0) return; // cut zero electron charge now, real threshold later
  Double_t smearedQ = SmearCharge(charge);
  if(smearedQ < fThreshold) {if(fVerboseLevel>3)Info("InjectStripCharge","Strip %i, charge %f below threshold %f",istrip,smearedQ,fThreshold); return;}
  if(fVerboseLevel>3) Info("InjectStripCharge","istrip=%i,charge=%f,smearedCharge=%f",istrip,charge,smearedQ);
  array.push_back( PndSdsStrip(Int_t(istrip),smearedQ) );
  return;
}

//______________________________________________________________________________
Double_t PndSdsCalcStrip::SmearCharge(Double_t charge)
{
  Double_t smeared = gRandom->Gaus(charge,fNoise);
  if (fVerboseLevel > 3) Info("SmearCharge:"," charge = %f, smeared = %f",charge,smeared);
  return smeared;
}


void PndSdsCalcStrip::Print() const
{
  std::cout<<"-I- PndSdsCalcStrip Info :"<<std::endl;
  std::cout<<"     pitch                  = "<<fPitch*10000.<<" um"<<std::endl;
  std::cout<<"     orientation angle      = "<<fOrient/TMath::Pi()*180.<<" deg"<<std::endl;
  std::cout<<"     nr of strips           = "<<fNrStrips<<std::endl;
  std::cout<<"     nr of channels per FE  = "<<fNrFeChannels<<std::endl;
  std::cout<<"     nr of frontends        = "<<fNrStrips/fNrFeChannels<<std::endl;
  std::cout<<"     anchor point           = ("<<fAnchor.X()<<","<<fAnchor.Y()<<")"<<std::endl;
  std::cout<<"     strip-direction vector = ("<<fStripDir.X()<<","<<fStripDir.Y()<<")"<<std::endl;
}