PndFsmSttPid.cxx

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//--------------------------------------------------------------------------
// File and Version Information:
//      $Id: PndFsmSttPid.cc,v 1.13 2007/05/24 08:07:40 klausg Exp $
//
// Description:
//      Class PndFsmSttPid
//
//  Implementation of the STT 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
//
//------------------------------------------------------------------------

//-----------------------
// This Class's Header --
//-----------------------
#include "PndFsmSttPid.h"

//-------------
// C Headers --
//-------------

//---------------
// C++ Headers --
//---------------
#include <math.h>
#include <iostream>

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

//-------------------------------
// Collaborating Class Headers --
//-------------------------------

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

//-----------------------------------------------------------------------
// Local Macros, Typedefs, Structures, Unions and Forward Declarations --
//-----------------------------------------------------------------------

//----------------
// Constructors --
//----------------

PndFsmSttPid::PndFsmSttPid()
{
  initParameters();

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

PndFsmSttPid::PndFsmSttPid(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 --
//--------------

PndFsmSttPid::~PndFsmSttPid()
{
}

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

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

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

  if (wasDetected && fabs(t->charge())>1e-8)
  {
     // now the dEdx information
    TParticlePDG* part = _fdbPDG->GetParticle(t->pdt());
    double mass = (part) ? part->Mass() : t->p4().M();
    double p=t->p4().Vect().Mag();

    // overall resolution for the dEdx measurement
    double dEdx = compdEdx(p,mass);
    double sig = _dEdxRes*dEdx;

    double m_e  = _fdbPDG->GetParticle(11)->Mass();
    double m_mu = _fdbPDG->GetParticle(13)->Mass();
    double m_pi = _fdbPDG->GetParticle(211)->Mass();
    double m_K  = _fdbPDG->GetParticle(321)->Mass();
    double m_p  = _fdbPDG->GetParticle(2212)->Mass();

    // compute the expected dEdx values for all particle types
    // we need these to determine the pdf's (gaussian around nominal dEdx with res sig)

    double dEdx_e  = compdEdx(p,m_e);
    double dEdx_mu = compdEdx(p,m_mu);
    double dEdx_pi = compdEdx(p,m_pi);
    double dEdx_K  = compdEdx(p,m_K);
    double dEdx_p  = compdEdx(p,m_p);

    double measdEdx = _rand->Gaus(dEdx,sig);

    result ->setSttdEdx(measdEdx,sig);

    if (dEdx_e)  result->setLHElectron( gauss(measdEdx,dEdx_e,sig) );
    if (dEdx_mu) result->setLHMuon( gauss(measdEdx,dEdx_mu,sig) );
    if (dEdx_pi) result->setLHPion( gauss(measdEdx,dEdx_pi,sig) );
    if (dEdx_K)  result->setLHKaon( gauss(measdEdx,dEdx_K,sig) );
    if (dEdx_p)  result->setLHProton(gauss(measdEdx,dEdx_p,sig) );
  }


  return result;
}

double
PndFsmSttPid::gauss(double x, double x0, double s)
{
  return (1.0/(sqrt(2.0*M_PI)*s))*
          exp(-(x-x0)*(x-x0)/(2.0*s*s));
}

double
PndFsmSttPid::compdEdx(double p, double M)
{
  double dEdX;

  p*=1000;
  M*=1000;

  const double Z=10;
  const double A=20;
  const double z=1;//charge of incident particle in unit of e

  double beta;
  beta=p/sqrt(M*M+p*p);//CalculateBeta(KE,M);

  double gamma;
  gamma=1./sqrt(1-beta*beta);

  const double I=10e-6*Z;//0.000188;//MeV
  const double me=0.511;//Mev/c2

  double Wmax;
  Wmax=(2*me*beta*beta*gamma*gamma) / (1 + 2*gamma*me/M + (me/M)*(me/M));

  //const double C1=0.1535;//MeV cm2/g

  double X,X0,X1;
  double kappa=0.307075;
  X0=0.201;
  X1=3;
  X=log10(beta*gamma);
  double delta;
  double C,a;
  C=-5.217;
  a=0.196;

  if(X<=X0)
    delta=0;
  else if(X<=X1)
    delta=2*log(10.)*X+C+a*(X1-X)*(X1-X)*(X1-X);
  else
    delta=2*log(10.)*X+C;

  dEdX= ( kappa * (Z/A)   * z*z /(beta*beta)) * (log(2*me*beta*beta*gamma*gamma*Wmax / (I*I)) - 2*beta*beta - delta); //-Dshell??

  return dEdX;
}

bool
PndFsmSttPid::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
PndFsmSttPid::print(ostream &o)
{
  o <<"Parameters for detector <"<<detName()<<">"<<endl;
  o  <<"  _thtMin = "<<_thtMin<<endl;
  o  <<"  _thtMax = "<<_thtMax<<endl;
  o  <<"  _ptmin = "<<_ptmin<<endl;
  o  <<"  _dEdxRes = "<<_dEdxRes << " (rel)"<< endl;
  o  <<"  _efficiency = "<<_efficiency<<endl;
}

void
PndFsmSttPid::initParameters()
{
  _detName         = "SttPid";
  _thtMin          = 7.765;
  _thtMax          = 159.44;
  _ptmin            = 0.15;
  _dEdxRes         = 0.2; // 20% dEdx resolution
  _efficiency      = 1.0;

}

bool
PndFsmSttPid::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 == "dEdxRes")
    _dEdxRes=value;
  else
  if (name == "efficiency")
    _efficiency=value;
  else
    knownName=false;

  return knownName;
}