#include <LaserBeamsTEC1.h>

Inheritance diagram for LaserBeamsTEC1:

Public Member Functions
void	GeneratePrimaries (G4Event *myEvent)
	shoot optical photons into the detector at the beginning of an event More...

	LaserBeamsTEC1 ()
	default constructor More...

	LaserBeamsTEC1 (G4int nPhotonsInGun, G4int nPhotonsInBeam, G4double PhotonEnergy)
	constructor More...

void	setOptPhotonPolar (G4double Angle)
	set the polarisation of the photons More...

	~LaserBeamsTEC1 ()
	destructor More...

Private Attributes
CLHEP::DRand48Engine *	theDRand48Engine

G4int	thenParticle

G4int	thenParticleInGun

G4ParticleGun *	theParticleGun

G4double	thePhotonEnergy

Detailed Description

Laser Beams in the right Endcap

Date:: 2007/06/11 14:44:28

Revision:: 1.3

Author: Maarten Thomas

Definition at line 21 of file LaserBeamsTEC1.h.

Constructor & Destructor Documentation

LaserBeamsTEC1::LaserBeamsTEC1 ( )

default constructor

Definition at line 20 of file LaserBeamsTEC1.cc.

 {
   G4int nPhotonsGun = 1;
   G4int nPhotonsBeam = 1;
   G4double Energy = 1.15 * eV;
   // call constructor with options
   LaserBeamsTEC1(nPhotonsGun, nPhotonsBeam, Energy);
 }

LaserBeamsTEC1::LaserBeamsTEC1	(	G4int	nPhotonsInGun,
		G4int	nPhotonsInBeam,
		G4double	PhotonEnergy
	)

constructor

Definition at line 29 of file LaserBeamsTEC1.cc.

References setOptPhotonPolar(), theDRand48Engine, thenParticle, thenParticleInGun, theParticleGun, and thePhotonEnergy.

                                                                                                : thenParticleInGun(0),
                                                    thenParticle(0),
                                                    thePhotonEnergy(0),
                                                    theParticleGun(),
                                                    theDRand48Engine()
 {
   /* *********************************************************************** */
   /*  initialize and configure the particle gun                              */
   /* *********************************************************************** */
 
   // the Photon energy
   thePhotonEnergy = PhotonEnergy;
 
   // number of particles in the Laser beam
   thenParticleInGun = nPhotonsInGun;
 
   // number of particles in one beam. ATTENTION: each beam contains nParticleInGun with the same
   // startpoint and direction. nParticle gives the number of particles in the beam with a different
   // startpoint. They are used to simulate the gaussian beamprofile of the Laser Beams.
   thenParticle = nPhotonsInBeam;
 
   // create the particle gun
   theParticleGun = new G4ParticleGun(thenParticleInGun);
 
   // default kinematics
   G4ParticleTable * theParticleTable = G4ParticleTable::GetParticleTable();
   G4ParticleDefinition * theOpticalPhoton = theParticleTable->FindParticle("opticalphoton");
 
   theParticleGun->SetParticleDefinition(theOpticalPhoton);
   theParticleGun->SetParticleTime(0.0 * ns);
   theParticleGun->SetParticlePosition(G4ThreeVector(-500.0 * cm, 0.0 * cm, 0.0 * cm));
   theParticleGun->SetParticleMomentumDirection(G4ThreeVector(5.0, 3.0, 0.0));
   theParticleGun->SetParticleEnergy(10.0 * keV);
   setOptPhotonPolar(90.0);
 
   // initialize the random number engine
   theDRand48Engine = new CLHEP::DRand48Engine();
 
 }

LaserBeamsTEC1::~LaserBeamsTEC1 ( )

destructor

Definition at line 69 of file LaserBeamsTEC1.cc.

References theDRand48Engine, and theParticleGun.

 {
   if ( theParticleGun != 0 )  { delete theParticleGun; }
   if ( theDRand48Engine != 0 ) { delete theDRand48Engine; }
 }

Member Function Documentation

void LaserBeamsTEC1::GeneratePrimaries ( G4Event * myEvent )

shoot optical photons into the detector at the beginning of an event

Definition at line 75 of file LaserBeamsTEC1.cc.

References funct::cos(), M_PI, edm::RandomNumberGenerator::mySeed(), setOptPhotonPolar(), funct::sin(), theDRand48Engine, thenParticle, theParticleGun, and thePhotonEnergy.

Referenced by LaserPrimaryGeneratorAction::GeneratePrimaries().

 {
   // this function is called at the beginning of an Event in LaserAlignment::upDate(const BeginOfEvent * myEvent)
 
   // use the random number generator service of the framework
   edm::Service<edm::RandomNumberGenerator> rng;
   unsigned int seed = rng->mySeed();
 
   // set the seed
   theDRand48Engine->setSeed(seed);
 
   // number of LaserRings and Laserdiodes
   const G4int nLaserRings = 2;
   const G4int nLaserBeams = 8;
 
   // z position of the sixth Tracker Endcap Disc, where the Laserdiodes are positioned
   G4double LaserPositionZ = 2057.5 * mm;
 
   // Radius of the inner and outer Laser ring
   G4double LaserRingRadius[nLaserRings] = {564.0 * mm, 840.0 * mm};
 
   // phi position of the first Laserdiode
   G4double LaserPhi0 = 0.392699082;
 
   // width of the LaserBeams
   G4double LaserRingSigmaX[nLaserRings] = {0.5 * mm, 0.5 * mm};
   G4double LaserRingSigmaY[nLaserRings] = {0.5 * mm, 0.5 * mm};
 
   // get the definition of the optical photon
   G4ParticleTable * theParticleTable = G4ParticleTable::GetParticleTable();
   G4ParticleDefinition * theOpticalPhoton= theParticleTable->FindParticle("opticalphoton");
   
   // loop over the LaserRings
   for (int theRing = 0; theRing < nLaserRings; theRing++)
     {
       // loop over the LaserBeams
       for (int theBeam = 0; theBeam < nLaserBeams; theBeam++)
     {
       // code for forward and backward beam
       // calculate the right phi for the current beam
       G4double LaserPositionPhi = LaserPhi0 + G4double(theBeam * G4double(G4double(2 * M_PI) / nLaserBeams));
 
       // calculate x and y position for the current beam
       G4double LaserPositionX = cos(LaserPositionPhi) * LaserRingRadius[theRing];
       G4double LaserPositionY = sin(LaserPositionPhi) * LaserRingRadius[theRing];
 
       // loop over all the particles in one beam
       for (int theParticle = 0; theParticle < thenParticle; theParticle++)
         {
           // get randomnumbers  and calculate the position
           CLHEP::RandGaussQ aGaussObjX( *theDRand48Engine, LaserPositionX, LaserRingSigmaX[theRing] );
           CLHEP::RandGaussQ aGaussObjY( *theDRand48Engine, LaserPositionY, LaserRingSigmaY[theRing] );
 
           G4double theXPosition = aGaussObjX.fire();
           G4double theYPosition = aGaussObjY.fire();
           G4double theZPosition = LaserPositionZ;
 
           // set the properties of the newly created particle
           theParticleGun->SetParticleDefinition(theOpticalPhoton);
           theParticleGun->SetParticleTime(0.0 * ns);
           theParticleGun->SetParticlePosition(G4ThreeVector(theXPosition, theYPosition, theZPosition));
           theParticleGun->SetParticleEnergy(thePhotonEnergy);
 
           // loop over both directions of the beam
           for (int theDirection = 0; theDirection < 2; theDirection++)
         {
           // shoot in both beam directions ...
           if (theDirection == 0)  // shoot in forward direction (+z)
             {
               theParticleGun->SetParticleMomentumDirection(G4ThreeVector(0.0, 0.0, 1.0));
               // set the polarization
               setOptPhotonPolar(90.0);
               // generate the particle
               theParticleGun->GeneratePrimaryVertex(myEvent);
             }
 
           if (theDirection == 1)  // shoot in backward direction (-z)
             {
               theParticleGun->SetParticleMomentumDirection(G4ThreeVector(0.0, 0.0, -1.0));
               // set the polarization
               setOptPhotonPolar(90.0);
               // generate the particle
               theParticleGun->GeneratePrimaryVertex(myEvent);
             }
         } // end loop over both beam directions
         } // end loop over particles in beam
     } // end loop over beams
     } // end loop over rings
 }

void LaserBeamsTEC1::setOptPhotonPolar ( G4double Angle )

set the polarisation of the photons

Definition at line 165 of file LaserBeamsTEC1.cc.

References funct::cos(), funct::sin(), mathSSE::sqrt(), and theParticleGun.

Referenced by GeneratePrimaries(), and LaserBeamsTEC1().

 {
   /* *********************************************************************** */
   /*   to get optical processes working properly, you have to make sure      *
    *   that the photon polarisation is defined.                              */
   /* *********************************************************************** */
 
   // first check if we have an optical photon
   if ( theParticleGun->GetParticleDefinition()->GetParticleName() != "opticalphoton" )
     { 
       edm::LogWarning("SimLaserAlignment:LaserBeamsTEC1") << "<LaserBeamsTEC1::SetOptPhotonPolar()>: WARNING! The ParticleGun is not an optical photon";
       return;
     }
 
 //   G4cout << "  AC1CMS: The ParticleGun is an " << theParticleGun->GetParticleDefinition()->GetParticleName();
   G4ThreeVector normal(1.0, 0.0, 0.0);
   G4ThreeVector kphoton = theParticleGun->GetParticleMomentumDirection();
   G4ThreeVector product = normal.cross(kphoton);
   G4double modul2 = product * product;
 
   G4ThreeVector e_perpendicular(0.0, 0.0, 1.0);
   
   if ( modul2 > 0.0 ) { e_perpendicular = (1.0 / sqrt(modul2)) * product; }
   
   G4ThreeVector e_parallel = e_perpendicular.cross(kphoton);
 
   G4ThreeVector polar = cos(Angle) * e_parallel + sin(Angle) * e_perpendicular;
   
 //   G4cout << ", the polarization = " << polar << G4endl;
   theParticleGun->SetParticlePolarization(polar);
 }