MedicalBeam.cc

Go to the documentation of this file.

//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************
//
// $Id: MedicalBeam.cc,v 1.6 2006-06-29 15:30:10 gunter Exp $
// $Name: not supported by cvs2svn $
// ====================================================================
//   MedicalBeam.cc
//
//                                         2005 Q
// ====================================================================
#include "MedicalBeam.hh"
#include "Randomize.hh"
#include "G4Event.hh"
#include "G4ParticleTable.hh"
#include "G4PrimaryVertex.hh"

using namespace CLHEP;

#include <cmath>

// ====================================================================
//
// class description
//
// ====================================================================

MedicalBeam::MedicalBeam()
  : particle(0), 
    kineticE(1.*MeV),
    sourcePosition(G4ThreeVector()),
    SSD(1.*m), 
    fieldShape(MedicalBeam::SQUARE),
    fieldR(10.*cm)
{
  fieldXY[0]= fieldXY[1]= 10.*cm;
}


MedicalBeam::~MedicalBeam()
{
}


G4ThreeVector MedicalBeam::GenerateBeamDirection() const
{
  // uniform distribution in a limitted solid angle
  G4double dr;
  if(fieldShape == MedicalBeam::SQUARE) {
    dr= std::sqrt(sqr(fieldXY[0]/2.)+sqr(fieldXY[1]/2.));
  } else {
    dr= fieldR;
  }

  G4double sin0= dr/SSD;
  G4double cos0= std::sqrt(1.-sqr(sin0));

  G4double dcos, dsin, dphi, z;

  G4double x= DBL_MAX;
  G4double y= DBL_MAX;

  G4double xmax, ymax;
  if(fieldShape == MedicalBeam::SQUARE) {
    xmax= fieldXY[0]/2./SSD;
    ymax= fieldXY[1]/2./SSD;
  } else {
    xmax= ymax= DBL_MAX-1.;
  }

  while(! (std::abs(x)< xmax && std::abs(y)< ymax) ) {
    dcos= RandFlat::shoot(cos0, 1.);
    dsin= std::sqrt(1.-sqr(dcos));
    dphi= RandFlat::shoot(0., twopi);

    x= std::cos(dphi)*dsin*dcos;
    y= std::sin(dphi)*dsin*dcos;
  }
  z= dcos;

  return G4ThreeVector(x,y,z);
}


void MedicalBeam::GeneratePrimaries(G4Event* anEvent)
{
  if(particle==0) return;

  // create a new vertex
  G4PrimaryVertex* vertex= new G4PrimaryVertex(sourcePosition, 0.*ns);

  // momentum
  G4double mass= particle-> GetPDGMass();
  G4double p= std::sqrt(sqr(mass+kineticE)-sqr(mass));
  G4ThreeVector pmon= p*GenerateBeamDirection();
  G4PrimaryParticle* primary= new G4PrimaryParticle(particle, 
                            pmon.x(), 
                            pmon.y(), 
                            pmon.z());
  // set primary to vertex
  vertex-> SetPrimary(primary);

  // set vertex to event
  anEvent-> AddPrimaryVertex(vertex);
}