MultipleScatteringSimulator Class Reference

#include <MultipleScatteringSimulator.h>

Inheritance diagram for MultipleScatteringSimulator:

Public Member Functions
	MultipleScatteringSimulator (double A, double Z, double density, double radLen)
	Default Constructor. More...
	~MultipleScatteringSimulator ()
	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 (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, RandomEngineAndDistribution const *)
	Compute the material effect (calls the sub class) More...
virtual	~MaterialEffectsSimulator ()

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

Private Attributes
double	sqr12
	Save (a tiny bit of) time. 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
int	theClosestChargedDaughterId
GlobalVector	theNormalVector
double	Z

Detailed Description

Definition at line 26 of file MultipleScatteringSimulator.h.

Constructor & Destructor Documentation

MultipleScatteringSimulator::MultipleScatteringSimulator	(	double	A,
		double	Z,
		double	density,
		double	radLen
	)

Default Constructor.

Definition at line 6 of file MultipleScatteringSimulator.cc.

References sqr12, and mathSSE::sqrt().

                                                     :
    MaterialEffectsSimulator(A,Z,density,radLen)
{
  sqr12 = std::sqrt(12.);
}

MultipleScatteringSimulator::~MultipleScatteringSimulator ( )

inline

Default Destructor.

Definition at line 34 of file MultipleScatteringSimulator.h.

{} ;

Member Function Documentation

void MultipleScatteringSimulator::compute ( ParticlePropagator &  Particle, RandomEngineAndDistribution const *  random  )

privatevirtual

The real dE/dx generation and particle update.

Implements MaterialEffectsSimulator.

Definition at line 13 of file MultipleScatteringSimulator.cc.

References RawParticle::charge(), funct::cos(), delta, alignCSCRings::e, RandomEngineAndDistribution::flatShoot(), RandomEngineAndDistribution::gaussShoot(), log, RawParticle::mass(), MaterialEffectsSimulator::orthogonal(), p2, phi, MaterialEffectsSimulator::radLengths, MaterialEffectsSimulator::radLenIncm(), RawParticle::rotate(), funct::sin(), sqr12, mathSSE::sqrt(), MaterialEffectsSimulator::theNormalVector, theta(), RawParticle::translate(), PV3DBase< T, PVType, FrameType >::x(), PV3DBase< T, PVType, FrameType >::y(), and PV3DBase< T, PVType, FrameType >::z().

{

  double p2 = Particle.Vect().Mag2();
  double m2 = Particle.mass()*Particle.mass();
  double e = std::sqrt(p2+m2);

  double pbeta = p2/e;  // This is p*beta

  // Average multiple scattering angle from Moliere radius
  // The sqrt(2) factor is because of the *space* angle
  double theta0 = 0.0136 / pbeta * Particle.charge() 
                                 * std::sqrt(2.*radLengths) 
                                 * (1. + 0.038*std::log(radLengths));

  // Generate multiple scattering space angle perpendicular to the particle motion
  double theta = random->gaussShoot(0.,theta0); 
  // Plus a random rotation angle around the particle motion
  double phi = 2. * 3.14159265358979323 * random->flatShoot();
  // The two rotations
  RawParticle::Rotation rotation1(orthogonal(Particle.Vect()),theta);
  RawParticle::Rotation rotation2(Particle.Vect(),phi);
  // Rotate!
  Particle.rotate(rotation1); 
  Particle.rotate(rotation2);

  // Generate mutiple scattering displacements in cm (assuming the detectors
  // are silicon only to determine the thickness) in the directions orthogonal
  // to the vector normal to the surface
  double xp = (cos(phi)*theta/2. + random->gaussShoot(0.,theta0)/sqr12)
              * radLengths * radLenIncm();       
  double yp = (sin(phi)*theta/2. + random->gaussShoot(0.,theta0)/sqr12)
              * radLengths * radLenIncm();

  // Determine a unitary vector tangent to the surface
  // This tangent vector is unitary because "normal" is
  // either (0,0,1) in the Endcap  or (x,y,0) in the Barrel !
  XYZVector normal(theNormalVector.x(),theNormalVector.y(),theNormalVector.z());
  XYZVector tangent = orthogonal(normal); 
  // The total displacement 
  XYZVector delta = xp*tangent + yp*normal.Cross(tangent);
  // Translate!
  Particle.translate(delta);

}

Member Data Documentation

double MultipleScatteringSimulator::sqr12

private

Save (a tiny bit of) time.

Definition at line 44 of file MultipleScatteringSimulator.h.

Referenced by compute(), and MultipleScatteringSimulator().