Implementation of the JScatteringModel interface with scattering according to the Henyey-Greenstein function. More...

#include <JScatteringModel.hh>

Inheritance diagram for JMARKOV::JHenyeyGreensteinScattering:

Public Member Functions
	JHenyeyGreensteinScattering (double _lambda_scat, double _g)
	Constructor. More...

double	getScatteringProbability (double ct)
	Return the probability density as a function of cos(theta) More...

JVersor3D	generateDirection ()
	Return a randomly generated direction according to the scattering probability distribution. More...

virtual double	getScatteringLength ()

Protected Attributes
double	g

double	lambda_scat

Detailed Description

Implementation of the JScatteringModel interface with scattering according to the Henyey-Greenstein function.

Definition at line 402 of file JScatteringModel.hh.

Constructor & Destructor Documentation

JMARKOV::JHenyeyGreensteinScattering::JHenyeyGreensteinScattering	(	double	_lambda_scat,
		double	_g
	)

inline

Constructor.

g is a parameter that determines how forward the scattering is. g = 0 corresponds to isotropic scattering g = 1 corresponds to fully forward scattering

Definition at line 413 of file JScatteringModel.hh.

                                                                   {
       lambda_scat  = _lambda_scat ;
       g = _g ;
     }

Member Function Documentation

double JMARKOV::JHenyeyGreensteinScattering::getScatteringProbability ( double ct )

inlinevirtual

Return the probability density as a function of cos(theta)

dP / dOmega = dP / dcosTheta dPhi

to scatter in a given direction. Theta=0 is forward scattering.

Implements JMARKOV::JScatteringModel.

Definition at line 418 of file JScatteringModel.hh.

                                                  {
       //double ct = cos(dir.getTheta()) ;
       double den = 1 + g*g - 2*g*ct ;
       return (1-g*g)/(4*M_PI*den*sqrt(den)) ;
     }

JVersor3D JMARKOV::JHenyeyGreensteinScattering::generateDirection ( )

inlinevirtual

Return a randomly generated direction according to the scattering probability distribution.

This uses gRandom.

Implements JMARKOV::JScatteringModel.

Definition at line 424 of file JScatteringModel.hh.

                                   {
       double phi = gRandom->Uniform(0,2*M_PI) ;
       double ct ;
       if( g>0 ) { 
         double xi  = gRandom->Uniform(0,1) ;
         ct  = 1.0/(2*g) * ( 1 + g*g - (1-g*g)*(1-g*g)/( (1-g+2*g*xi)*(1-g+2*g*xi) ) ) ;
       } else {
         ct = gRandom->Uniform(-1,1) ;
       }
       return JVersor3D( JAngle3D( acos(ct),phi) ) ;
     }