#include <EnergyLossSimulator.h>

Inheritance diagram for EnergyLossSimulator:

Public Member Functions
const XYZTLorentzVector &	deltaMom () const
	Returns the actual energy lost. More...

	EnergyLossSimulator (const RandomEngine *engine, double A, double Z, double density, double radLen)
	Constructor. More...

double	mostLikelyLoss () const
	Return most probable energy loss. More...

	~EnergyLossSimulator ()
	Default Destructor. More...

Public Member Functions inherited from MaterialEffectsSimulator
RHEP_const_iter	beginDaughters () const
	Returns const iterator to the beginning of the daughters list. More...

int	closestDaughterId ()
	The id of the closest charged daughter (filled for nuclear interactions only) More...

double	eMass () const
	Electron mass in GeV/c2. More...

RHEP_const_iter	endDaughters () const
	Returns const iterator to the end of the daughters list. More...

double	excitE () const
	Mean excitation energy (in GeV) More...

	MaterialEffectsSimulator (const RandomEngine *engine, double A=28.0855, double Z=14.0000, double density=2.329, double radLen=9.360)

unsigned	nDaughters () const
	Returns the number of daughters. More...

XYZVector	orthogonal (const XYZVector &) const
	A vector orthogonal to another one (because it's not in XYZTLorentzVector) More...

double	radLenIncm () const
	One radiation length in cm. More...

double	rho () const
	Density in g/cm3. More...

void	setNormalVector (const GlobalVector &normal)
	Sets the vector normal to the surface traversed. More...

double	theA () const
	A. More...

double	theZ () const
	Z. More...

void	updateState (ParticlePropagator &myTrack, double radlen)
	Compute the material effect (calls the sub class) More...

virtual	~MaterialEffectsSimulator ()

Private Member Functions
void	compute (ParticlePropagator &Particle)
	The real dE/dx generation and particle update. More...

Private Attributes
XYZTLorentzVector	deltaP
	The actual energy loss. More...

double	mostProbableLoss
	The most probable enery loss. More...

LandauFluctuationGenerator *	theGenerator
	The Landau Fluctuation generator. More...

Additional Inherited Members
Public Types inherited from MaterialEffectsSimulator
typedef std::vector < RawParticle > ::const_iterator	RHEP_const_iter

Protected Attributes inherited from MaterialEffectsSimulator
std::vector< RawParticle >	_theUpdatedState

double	A

double	density

double	radLen

double	radLengths

const RandomEngine *	random

int	theClosestChargedDaughterId

GlobalVector	theNormalVector

double	Z

Detailed Description

Definition at line 26 of file EnergyLossSimulator.h.

Constructor & Destructor Documentation

EnergyLossSimulator::EnergyLossSimulator	(	const RandomEngine *	engine,
		double	A,
		double	Z,
		double	density,
		double	radLen
	)

Constructor.

Definition at line 7 of file EnergyLossSimulator.cc.

References theGenerator.

                                                                         :
     MaterialEffectsSimulator(engine,A,Z,density,radLen) 
 {
 
   theGenerator = new LandauFluctuationGenerator(engine);
 
 }

EnergyLossSimulator::~EnergyLossSimulator ( )

Default Destructor.

Definition at line 16 of file EnergyLossSimulator.cc.

References theGenerator.

                                           {
 
   delete theGenerator;
 
 }

Member Function Documentation

void EnergyLossSimulator::compute ( ParticlePropagator & Particle )

privatevirtual

The real dE/dx generation and particle update.

Implements MaterialEffectsSimulator.

Definition at line 23 of file EnergyLossSimulator.cc.

References RawParticle::charge(), deltaP, reco::e2, MaterialEffectsSimulator::eMass(), MaterialEffectsSimulator::excitE(), LandauFluctuationGenerator::landau(), create_public_lumi_plots::log, RawParticle::mass(), max(), mostProbableLoss, p2, MaterialEffectsSimulator::radLengths, MaterialEffectsSimulator::radLenIncm(), MaterialEffectsSimulator::rho(), mathSSE::sqrt(), MaterialEffectsSimulator::theA(), theGenerator, and MaterialEffectsSimulator::theZ().

 {
 
   //  FamosHistos* myHistos = FamosHistos::instance();
 
   // double gamma_e = 0.577215664901532861;  // Euler constant
   
   // The thickness in cm
   double thick = radLengths * radLenIncm();
   
   // This is a simple version (a la PDG) of a dE/dx generator.
   // It replaces the buggy GEANT3 -> C++ former version.
   // Author : Patrick Janot - 8-Jan-2004
 
   double p2  = Particle.Vect().Mag2();
   double verySmallP2 = 0.0001;
   if (p2<=verySmallP2) {
     deltaP.SetXYZT(0.,0.,0.,0.);
     return;
   }
   double m2  = Particle.mass() * Particle.mass();
   double e2  = p2+m2;
 
   double beta2 = p2/e2;
   double gama2 = e2/m2;
   
   double charge2 = Particle.charge() * Particle.charge();
   
   // Energy loss spread in GeV
   double eSpread  = 0.1536E-3*charge2*(theZ()/theA())*rho()*thick/beta2;
  
   // Most probable energy loss (from the integrated Bethe-Bloch equation)
   mostProbableLoss = eSpread * ( log ( 2.*eMass()*beta2*gama2*eSpread
                              / (excitE()*excitE()) )
                                  - beta2 + 0.200 );
 
   // This one can be needed on output (but is not used internally)
   // meanEnergyLoss = 2.*eSpread * ( log ( 2.*eMass()*beta2*gama2 /excitE() ) - beta2 );
 
   // Generate the energy loss with Landau fluctuations
   double dedx = mostProbableLoss + eSpread * theGenerator->landau();
 
   // Compute the new energy and momentum
   double aBitAboveMass = Particle.mass()*1.0001;
   double newE = std::max(aBitAboveMass,Particle.e()-dedx);
   //  double newE = std::max(Particle.mass(),Particle.e()-dedx);
   double fac  = std::sqrt((newE*newE-m2)/p2);
 
   
   // Update the momentum
   deltaP.SetXYZT(Particle.Px()*(1.-fac),Particle.Py()*(1.-fac),
          Particle.Pz()*(1.-fac),Particle.E()-newE);
   Particle.SetXYZT(Particle.Px()*fac,Particle.Py()*fac, 
            Particle.Pz()*fac,newE);
   
 }