#include <MultipleScatteringSimulator.h>

Inheritance diagram for MultipleScatteringSimulator:

Public Member Functions
	MultipleScatteringSimulator (double A, double Z, double density, double radLen)
	Default Constructor. More...

	~MultipleScatteringSimulator () override
	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...

virtual void	save ()
	Used by NuclearInteractionSimulator to save last sampled event. 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 *) override
	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::MultipleScatteringSimulator	(	double	A,
		double	Z,
		double	density,
		double	radLen
	)

Default Constructor.

Definition at line 6 of file MultipleScatteringSimulator.cc.

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

References sqr12, and mathSSE::sqrt().

◆ ~MultipleScatteringSimulator()

MultipleScatteringSimulator::~MultipleScatteringSimulator ( )

inlineoverride

Default Destructor.

Definition at line 32 of file MultipleScatteringSimulator.h.

32 {};

Member Function Documentation

◆ compute()

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

overrideprivatevirtual

The real dE/dx generation and particle update.

Implements MaterialEffectsSimulator.

Definition at line 11 of file MultipleScatteringSimulator.cc.

                                                                                                                  {
   double p2 = Particle.particle().Vect().Mag2();
   double m2 = Particle.particle().mass() * Particle.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.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.particle().Vect()), theta);
   RawParticle::Rotation rotation2(Particle.particle().Vect(), phi);
   // Rotate!
   Particle.particle().rotate(rotation1);
   Particle.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.particle().translate(delta);
 }