#include <LaserBeamsBarrel.h>

Inheritance diagram for LaserBeamsBarrel:

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

	LaserBeamsBarrel ()
	default constructor More...

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

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

	~LaserBeamsBarrel ()
	destructor More...

Private Attributes
CLHEP::DRand48Engine *	theDRand48Engine

G4int	thenParticle

G4int	thenParticleInGun

G4ParticleGun *	theParticleGun

G4double	thePhotonEnergy

Detailed Description

Define the LaserBeams which connect both TECs and TIB and TOB with eachother

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

Revision:: 1.3

Author: Maarten Thomas

Definition at line 21 of file LaserBeamsBarrel.h.

Constructor & Destructor Documentation

LaserBeamsBarrel::LaserBeamsBarrel ( )

default constructor

Definition at line 20 of file LaserBeamsBarrel.cc.

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

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

constructor

Definition at line 29 of file LaserBeamsBarrel.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();
 
 }

LaserBeamsBarrel::~LaserBeamsBarrel ( )

destructor

Definition at line 69 of file LaserBeamsBarrel.cc.

References theDRand48Engine, and theParticleGun.

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

Member Function Documentation

void LaserBeamsBarrel::GeneratePrimaries ( G4Event * myEvent )

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

Definition at line 75 of file LaserBeamsBarrel.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 LaserBeams
   const G4int nLaserBeams = 8;
 
   // z position of the Laserdiodes (value from design drawings)
   G4double LaserPositionZ = 1137.0 * mm; 
 
   // Radius of the Laser ring
   G4double LaserRingRadius = 564.0 * mm;
 
   // phi positions of the Laserdiodes (from CMS Note 2001/053 or from http://abbaneo.home.cern.ch/abbaneo/cms/layout)
   G4double LaserPhi[nLaserBeams] = { G4double(7.0/112.0)   * G4double(2.0 * M_PI),
                      G4double(23.0/112.0)  * G4double(2.0 * M_PI),
                      G4double(33.0/112.0)  * G4double(2.0 * M_PI),
                      G4double(49.0/112.0)  * G4double(2.0 * M_PI),
                      G4double(65.0/112.0)  * G4double(2.0 * M_PI),
                      G4double(77.0/112.0)  * G4double(2.0 * M_PI),
                      G4double(93.0/112.0)  * G4double(2.0 * M_PI),
                      G4double(103.0/112.0) * G4double(2.0 * M_PI) };
 
   // width of the LaserBeams
   G4double LaserBeamSigmaX = 0.5 * mm;
   G4double LaserBeamSigmaY = 0.5 * mm;
 
   // get the definition of the optical photon
   G4ParticleTable * theParticleTable = G4ParticleTable::GetParticleTable();
   G4ParticleDefinition * theOpticalPhoton = theParticleTable->FindParticle("opticalphoton");
 
   // loop over the LaserBeams
   for (int theBeam = 0; theBeam < nLaserBeams; theBeam++)
     {
       // code for forward and backward beam
       // calculate x and y position of the current laser diode
       G4double LaserPositionX = cos(LaserPhi[theBeam]) * LaserRingRadius;
       G4double LaserPositionY = sin(LaserPhi[theBeam]) * LaserRingRadius;
 
       // 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, LaserBeamSigmaX );
       CLHEP::RandGaussQ aGaussObjY( *theDRand48Engine, LaserPositionY, LaserBeamSigmaY );
       
       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);
         }
           else 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 looop over both beam directions
     } // end looop over particles in beam
     } // end loop over beams
 }

void LaserBeamsBarrel::setOptPhotonPolar ( G4double Angle )

set the polarisation of the photons

Definition at line 163 of file LaserBeamsBarrel.cc.

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

Referenced by GeneratePrimaries(), and LaserBeamsBarrel().

 {
   /* *********************************************************************** */
   /*   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:LaserBeamsBarrel") << "<LaserBeamsBarrel::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);
 }