TpcSimDriftChamber.cxx

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#include "TpcSimDriftChamber.h"

#include "HarpoConfig.h"

#include "TRandom3.h"
#include "TMath.h"

ClassImp(TpcSimDriftChamber)

TpcSimDriftChamber::TpcSimDriftChamber()
{
  fDiffX = 0.08;             //
  fDiffY = 0.08;             // mm/sqrt(mm)
  fDiffZ = 0.05;             //

  fDriftVelocity = 60;//33;  // mm/us

  fElectronCapture = 0.001;      // 1/mm

  fZReadout = 0;             // mm
  fLengthTpc = 300;           // mm


  Double_t diffX;
  if ( ! gHConfig->Lookup("Sim.DiffX",diffX) )
    Info("Constructor","Use default DiffX %g",fDiffX);
  else
    fDiffX = diffX;

  Double_t diffY;
  if ( ! gHConfig->Lookup("Sim.DiffY",diffY) )
    Info("Constructor","Use default DiffY %g",fDiffY);
  else
    fDiffY = diffY;

  Double_t diffZ;
  if ( ! gHConfig->Lookup("Sim.DiffZ",diffZ) )
    Info("Constructor","Use default DiffZ %g",fDiffZ);
  else
    fDiffZ = diffZ;

  Double_t driftVelocity;
  if ( ! gHConfig->Lookup("Sim.DriftVelocity",driftVelocity) )
    Info("Constructor","Use default DriftVelocity %g",fDriftVelocity);
  else
    fDriftVelocity = driftVelocity;

  Double_t electronCapture;
  if ( ! gHConfig->Lookup("Sim.ElectronCapture",electronCapture) )
    Info("Constructor","Use default ElectronCapture %g",fElectronCapture);
  else
    fElectronCapture = electronCapture;

  Double_t zReadout;
  if ( ! gHConfig->Lookup("Sim.ZReadout",zReadout) )
    Info("Constructor","Use default ZReadout %g",fZReadout);
  else
    fZReadout = zReadout;

  Double_t lengthTpc;
  if ( ! gHConfig->Lookup("Sim.LengthTpc",lengthTpc) )
    Info("Constructor","Use default ZReadout %g",fLengthTpc);
  else
    fLengthTpc = lengthTpc;

}



TpcSimDriftChamber::~TpcSimDriftChamber()
{
}



Int_t TpcSimDriftChamber::DriftElectron(Double_t x0, Double_t y0, Double_t z0, Double_t t0, Double_t &xEnd, Double_t &yEnd, Double_t &zEnd, Double_t &tEnd)
{

  if(z0<fZReadout && fDriftVelocity>=0) return -1;
  if(z0>fZReadout && fDriftVelocity<=0) return -1;
  if(fDriftVelocity>=0){
    if(z0<fZReadout) return -1;
    if(z0>fZReadout + fLengthTpc) return -1;
  }else{
    if(z0>fZReadout) return -1;
    if(z0<fZReadout - fLengthTpc) return -1;
  }

  Double_t r = gRandom->Rndm();
  if(r>TMath::Exp(-fElectronCapture*TMath::Abs(z0-fZReadout))) return 0;

  Double_t driftDistance = TMath::Abs(z0-fZReadout);

  Double_t diffX = fDiffX*TMath::Sqrt(driftDistance);
  Double_t diffY = fDiffY*TMath::Sqrt(driftDistance);
  Double_t diffZ = fDiffZ*TMath::Sqrt(driftDistance);

  xEnd = gRandom->Gaus(x0,diffX);
  yEnd = gRandom->Gaus(y0,diffY);
  driftDistance += gRandom->Gaus(0,diffZ);

  Double_t driftTime = driftDistance/TMath::Abs(fDriftVelocity);
  tEnd = t0 + driftTime;

  // Info("DriftElectron","%f + %f = %f",t0,driftTime,tEnd);

  zEnd = fZReadout;

  return 1;
}