PndFsmMvdPid.cxx

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//--------------------------------------------------------------------------
// File and Version Information:
//      $Id: PndFsmMvdPid.cc,v 1.10 2007/05/24 08:07:40 klausg Exp $
//
// Description:
//      Class PndFsmMvdPid
//
//  Implementation of the MVD for the FastSim
//
//  This software was developed for the PANDA collaboration.  If you
//  use all or part of it, please give an appropriate acknowledgement.
//
// Author List:
//      Klaus Goetzen                    Original Author
//
// Copyright Information:
//      Copyright (C) 2006              GSI
//
//------------------------------------------------------------------------

#include "PndFsmMvdPid.h"
#include <math.h>
#include <iostream>

using std::cout;
using std::endl;
using std::ostream;
using std::string;

#include "ArgList.h"
#include "PndFsmResponse.h"
#include "PndFsmTrack.h"

PndFsmMvdPid::PndFsmMvdPid()
{
  initParameters();

  _thtMin=_thtMin*M_PI/180.0;
  _thtMax=_thtMax*M_PI/180.0;
  //print(std::cout);
}

PndFsmMvdPid::PndFsmMvdPid(ArgList &par)
{
  initParameters();
  //set default parameter values and parses a parameter list
  //i.e. std::list<std::string> of the form
  //"a=1" "b=2" "c=3"
  parseParameterList(par);

  _thtMin=_thtMin*M_PI/180.0;
  _thtMax=_thtMax*M_PI/180.0;
  //print(std::cout);
}

//--------------
// Destructor --
//--------------

PndFsmMvdPid::~PndFsmMvdPid()
{
}

//--------------
// Operations --
//--------------

PndFsmResponse*
PndFsmMvdPid::respond(PndFsmTrack *t)
{
  PndFsmResponse *result=new PndFsmResponse();

  result->setDetector(this);
  bool wasDetected=detected(t);
  result->setDetected(wasDetected);

  if (wasDetected && fabs(t->charge())>1e-8)
  {
    //select particle
    PidType part;
    switch(abs(t->pdt())) {
      case 2212:part=proton; break;
      case 321: part=kaon; break;
      case 211: part=pion; break;
      case 13:  part=muon; break;
      case 11:  part=electron; break;
    }

    //build random energy loss
    _momentum = t->p4().Vect().Mag();
    _energyloss = MeanEnergyLoss(part) + mpv(part) + _rand->Landau(0, width1(part)) + _rand->Gaus(0, width2(part))*_dEdxResMulti;

    //store random energy loss
    result->setMvddEdx(_energyloss/1e-3);

    //store energy loss
    if (_momentum>=0 && _momentum<=2.5) {
      result->setLHElectron(Likelihood(electron));
      result->setLHMuon(Likelihood(muon));
      result->setLHPion(Likelihood(pion));
      result->setLHKaon(Likelihood(kaon));
      result->setLHProton(Likelihood(proton));
    } else {
      result->setLHElectron(0.2);
      result->setLHMuon(0.2);
      result->setLHPion(0.2);
      result->setLHKaon(0.2);
      result->setLHProton(0.2);
    }
  }

  return result;
}


bool
PndFsmMvdPid::detected(PndFsmTrack *t) const
{
    double theta = t->p4().Theta();
    double p_t=t->p4().Vect().Perp(TVector3(0.,0.,1.));
    double charge=t->charge();

    return ( charge!=0.0 && theta>=_thtMin && theta<=_thtMax && p_t>_ptmin  && _rand->Rndm()<=_efficiency);
}


void
PndFsmMvdPid::print(ostream &o)
{
  o <<"Parameters for detector <"<<detName()<<">"<<endl;
  o  <<"  _thtMin = "<<_thtMin<<endl;
  o  <<"  _thtMax = "<<_thtMax<<endl;
  o  <<"  _ptmin = "<<_ptmin<<endl;
  o  <<"  _dEdxResMulti = "<<100*_dEdxResMulti<< "\%" << endl;
  o  <<"  _efficiency = "<<_efficiency<<endl;
}

void
PndFsmMvdPid::initParameters()
{
  _detName         = "MvdPid";
  _thtMin          = 5.0;
  _thtMax          = 160.0;
  _ptmin            = 0.0;
  _dEdxResMulti    = 1.00; //normal energy loss resolution
  _efficiency      = 1.0;
}

bool
PndFsmMvdPid::setParameter(std::string &name, double value)
{
  // *****************
  // include here all parameters which should be settable via tcl
  // *****************

  bool knownName=true;

  if (name == "thtMin")
    _thtMin=value;
  else
  if (name == "thtMax")
    _thtMax=value;
  else
  if (name == "ptmin")
    _ptmin=value;
  else
  if (name == "dEdxResMulti")
    _dEdxResMulti=value;
  else
  if (name == "efficiency")
    _efficiency=value;
  else
    knownName=false;

  return knownName;
}

double PndFsmMvdPid::MeanEnergyLoss(PidType part) {
  //Calculate the lower boundary of the energy loss distribution.

  //[GeV]
  static float eb=0.14e-6;
  //[m/s]
  static float c=2.99792458e8;
  //[GeV/c**2]
  static float Mass[nPidType]={ 0.511e-3, 0.1058, 0.1396, 0.4937, 0.9383 };

  double sqrBeta=1/(1+pow(Mass[part]/_momentum,2));
  return 4.9312e-05 * (log(2*Mass[electron]*c*c/eb*sqrBeta/(1-sqrBeta))-sqrBeta)/sqrBeta;
};

double PndFsmMvdPid::LandauGaus(double s_mpv, double widthone, double widthtwo) {
  // this is the adapted TF1::Integral function from
  // ROOT 5.14. GOTOs have been removed and interval
  // division has been modified to maximize performance

  if (widthone<=0)
    return TMath::Gaus(s_mpv, 0, widthtwo, true);
  else if (widthtwo<=0)
    return TMath::Landau(s_mpv, 0, widthone, true);
  else {
    static double x[12] = { 0.96028985649753623,  0.79666647741362674,
                            0.52553240991632899,  0.18343464249564980,
                            0.98940093499164993,  0.94457502307323258,
                            0.86563120238783174,  0.75540440835500303,
                            0.61787624440264375,  0.45801677765722739,
                            0.28160355077925891,  0.09501250983763744};

    static double w[12] = { 0.10122853629037626,  0.22238103445337447,
                            0.31370664587788729,  0.36268378337836198,
                            0.02715245941175409,  0.06225352393864789,
                            0.09515851168249278,  0.12462897125553387,
                            0.14959598881657673,  0.16915651939500254,
                            0.18260341504492359,  0.18945061045506850};

    double h, bb, aa, c1, c2, u, s8, s16, f1, f2;
    double xx;
    bool redo=true;
    int i;

    h = 0;
    aa = -5.0*widthtwo;
    bb = -2.5*widthtwo;

    do {
      c1 = 0.5*(bb+aa);
      c2 = 0.5*(bb-aa);

      s8 = 0;
      for (i=0;i<4;i++) {
        u  = c2*x[i];
        xx = c1+u;
        f1 = TMath::Landau(s_mpv+xx, 0, widthone, true)*TMath::Gaus(xx, 0, widthtwo, true);
        xx = c1-u;
        f2 = TMath::Landau(s_mpv+xx, 0, widthone, true)*TMath::Gaus(xx, 0, widthtwo, true);
        s8+= w[i]*(f1 + f2);
      }
      s16 = 0;
      for (i=4;i<12;i++) {
        u   = c2*x[i];
        xx  = c1+u;
        f1  = TMath::Landau(s_mpv+xx, 0, widthone, true)*TMath::Gaus(xx, 0, widthtwo, true);
        xx  = c1-u;
        f2  = TMath::Landau(s_mpv+xx, 0, widthone, true)*TMath::Gaus(xx, 0, widthtwo, true);
        s16+= w[i]*(f1 + f2);
      }
      s16 = c2*s16;
      if (TMath::Abs(s16-c2*s8) <= 1e-12*(s16+1) ) {
        aa =bb;
        bb+=2*c2*1.5;
        if (bb>=5*widthtwo) {
          bb=5*widthtwo;
          redo=false;
        }
        h += s16;
      } else
        bb = c1;
    } while (redo);
    return h;
  }
}

double PndFsmMvdPid::Likelihood(PidType part) {
  return LandauGaus( _energyloss - MeanEnergyLoss(part) - mpv(part), width1(part), width2(part)*_dEdxResMulti );
}

double PndFsmMvdPid::mpv(PidType part) {
  double x=_momentum;
  double x0=0;
  double x1=0;
  double c0=0;
  double c1=0;
  double d1=0;
  double a3=0;
  double a4=0;
  double a5=0;

  switch(part) {
  case proton:
    x0 = 0.45;
    x1 = 1.3;
    c0 = 0.383451e-03;
    c1 = -0.126986e-03;
    d1 = -5.21351e-06;
    a3 = -3.05821;
    a4 = 24.6356;
    a5 = -68.632;
    break;
  case kaon:
    x0 = 0.25;
    x1 = 1.05;
    c0 = 0.326259e-03;
    c1 = -7.68052e-05;
    d1 = 1.51033e-05;
    a3 = -19.6615;
    a4 = 264.382;
    a5 = -1238.09;
    break;
  case pion:
    x0 = 0.1;
    x1 = 1.0;
    c0 = 0.274692e-03;
    c1 = 3.2571e-05;
    d1 = 9.16527e-06;
    a5 = -6624.05;
    break;
  case muon:
    x0 = 0.15;
    x1 = 1.15;
    a3 = 4.33244;
    a4 = -107.686;
    a5 = 699.522;
    c0 = 0.248749e-03;
    c1 = 6.57118e-05;
    d1 = -4.09447e-06;
    break;
  case electron:
    x1 = 1.20;
    c0 = 2.93999e-03;
    c1 = 1.76792e-05;
    break;
  }
  if (x>=x1)
    return c0+c1*(x1-x0)+d1*(x-x1);
  if (x>=x0)
    return c0+c1*(x-x0);
  else
    return c0+c1*(x-x0)+pow(x0-x,3)*(a3+(x0-x)*(a4+(x0-x)*a5));
}

double PndFsmMvdPid::width1(PidType part) {
  double x=_momentum;
  switch(part) {
  case proton:
    if (x>=1.10)
      return +3.81174e-04+x*(-2.25108e-04+x*+5.45154e-05);
    else
      return -5.28145e-05+x*(+8.29883e-04+x*-5.35972e-04);
    break;
  case kaon:
    if (x>=1.05)
      return +2.61134e-04+x*(-1.30818e-04+x*+3.44165e-05);
    else
      return +3.41858e-04+x*(-3.21115e-04+x*+1.37459e-04);
    break;
  case pion:
    if (x>=1.00)
      return +1.88718e-04+x*(-6.38948e-05+x*+1.78590e-05);
    else
      return +1.82872e-04+x*(-1.28373e-04+x*+8.01459e-05);
    break;
  case muon:
    if (x>=1.20)
      return +1.06142e-04+x*(+3.68777e-05+x*-1.00190e-05);
    else
      return +1.89374e-04+x*(-1.46441e-04+x*+9.10813e-05);
    break;
  case electron:
    if (x>1.2) x=1.2;
    // electrons are constant for momentum > 1.2GeV
    return +1.27955e-04+x*(-3.15732e-06+x*+9.64736e-06);
    break;
  }
  return 0;
}

double PndFsmMvdPid::width2(PidType part) {
  double x=_momentum;
  switch(part) {
  case proton:
    if (x>=1.10)
      return +6.41067e-04+x*(-3.82507e-04+x*+9.03732e-05);
    else
      return +6.40328e-04-3.21725e-04*x+3.17708e-05*pow(x,-3);
    break;
  case kaon:
    if (x>=1.05)
      return +2.22504e-04+x*(-6.40051e-06+x*+2.14434e-06);
    else
      return +3.86684e-04-1.61873e-04*x+7.76586e-06*pow(x,-3);
    break;
  case pion:
    if (x>=1.00)
      return +1.32999e-04+x*(+1.19714e-04+x*-3.53302e-05);
    else
      return +2.21603e-04-3.21357e-06*x+4.64793e-06*pow(x,-2);
    break;
  case muon:
   if (x>=1.20)
      return +7.84582e-05+x*(+1.88988e-04+x*-5.49637e-05);
    else
      return +1.67388e-04+5.67991e-05*x+3.42702e-06*pow(x,-2);
    break;
  case electron:
    if (x>1.2) x=1.2;
    // electrons are constant for momentum > 1.2GeV
    return +4.08849e-04-3.56548e-05*x+1.84825e-08*pow(x,-3);
    break;
  }
  return 0;
}