LaserAlignmentSimulation/src/LaserBeamsTEC2.cc

0001 /** \file LaserBeamsTEC2.cc
0002  *
0003  *
0004  *  $Date: 2010/09/09 18:22:48 $
0005  *  $Revision: 1.7 $
0006  *  \author Maarten Thomas
0007  */
0008
0009 #include "Alignment/LaserAlignmentSimulation/interface/LaserBeamsTEC2.h"
0010
0011 #include "FWCore/MessageLogger/interface/MessageLogger.h"
0012 #include "FWCore/ServiceRegistry/interface/Service.h"
0013 #include "FWCore/Utilities/interface/RandomNumberGenerator.h"
0014
0015 #include "CLHEP/Random/RandGaussQ.h"
0016 #include "CLHEP/Units/GlobalSystemOfUnits.h"
0017 #include "G4ParticleDefinition.hh"
0018 #include "G4ParticleGun.hh"
0019 #include "globals.hh"  // Global Constants and typedefs
0020
0021 LaserBeamsTEC2::LaserBeamsTEC2() : theParticleGun(nullptr), theDRand48Engine(nullptr) {
0022   G4int nPhotonsGun = 1;
0023   G4int nPhotonsBeam = 1;
0024   G4double Energy = 1.15 * eV;
0025   // call constructor with options
0026   LaserBeamsTEC2(nPhotonsGun, nPhotonsBeam, Energy);
0027 }
0028
0029 LaserBeamsTEC2::LaserBeamsTEC2(G4int nPhotonsInGun, G4int nPhotonsInBeam, G4double PhotonEnergy)
0030     : thenParticleInGun(0), thenParticle(0), thePhotonEnergy(0), theParticleGun(), theDRand48Engine() {
0031   /* *********************************************************************** */
0032   /*  initialize and configure the particle gun                              */
0033   /* *********************************************************************** */
0034
0035   // the Photon energy
0036   thePhotonEnergy = PhotonEnergy;
0037
0038   // number of particles in the Laser beam
0039   thenParticleInGun = nPhotonsInGun;
0040
0041   // number of particles in one beam. ATTENTION: each beam contains
0042   // nParticleInGun with the same startpoint and direction. nParticle gives the
0043   // number of particles in the beam with a different startpoint. They are used
0044   // to simulate the gaussian beamprofile of the Laser Beams.
0045   thenParticle = nPhotonsInBeam;
0046
0047   // create the particle gun
0048   theParticleGun = new G4ParticleGun(thenParticleInGun);
0049
0050   // default kinematics
0051   G4ParticleTable *theParticleTable = G4ParticleTable::GetParticleTable();
0052   G4ParticleDefinition *theOpticalPhoton = theParticleTable->FindParticle("opticalphoton");
0053
0054   theParticleGun->SetParticleDefinition(theOpticalPhoton);
0055   theParticleGun->SetParticleTime(0.0 * ns);
0056   theParticleGun->SetParticlePosition(G4ThreeVector(-500.0 * cm, 0.0 * cm, 0.0 * cm));
0057   theParticleGun->SetParticleMomentumDirection(G4ThreeVector(5.0, 3.0, 0.0));
0058   theParticleGun->SetParticleEnergy(10.0 * keV);
0059   setOptPhotonPolar(90.0);
0060
0061   // initialize the random number engine
0062   theDRand48Engine = new CLHEP::DRand48Engine();
0063 }
0064
0065 LaserBeamsTEC2::~LaserBeamsTEC2() {
0066   if (theParticleGun != nullptr) {
0067     delete theParticleGun;
0068   }
0069   if (theDRand48Engine != nullptr) {
0070     delete theDRand48Engine;
0071   }
0072 }
0073
0074 void LaserBeamsTEC2::GeneratePrimaries(G4Event *myEvent) {
0075   // this function is called at the beginning of an Event in
0076   // LaserAlignment::upDate(const BeginOfEvent * myEvent)
0077
0078   // use the random number generator service of the framework
0079   edm::Service<edm::RandomNumberGenerator> rng;
0080   unsigned int seed = rng->mySeed();
0081
0082   // set the seed
0083   theDRand48Engine->setSeed(seed);
0084
0085   // number of LaserRings and Laserdiodes
0086   const G4int nLaserRings = 2;
0087   const G4int nLaserBeams = 8;
0088
0089   // z position of the sixth Tracker Endcap Disc, where the Laserdiodes are
0090   // positioned
0091   G4double LaserPositionZ = -2057.5 * mm;
0092
0093   // Radius of the inner and outer Laser ring
0094   G4double LaserRingRadius[nLaserRings] = {564.0 * mm, 840.0 * mm};
0095
0096   // phi position of the first Laserdiode
0097   G4double LaserPhi0 = 0.392699082;
0098
0099   // width of the LaserBeams
0100   G4double LaserRingSigmaX[nLaserRings] = {0.5 * mm, 0.5 * mm};
0101   G4double LaserRingSigmaY[nLaserRings] = {0.5 * mm, 0.5 * mm};
0102
0103   // get the definition of the optical photon
0104   G4ParticleTable *theParticleTable = G4ParticleTable::GetParticleTable();
0105   G4ParticleDefinition *theOpticalPhoton = theParticleTable->FindParticle("opticalphoton");
0106
0107   // loop over the LaserRings
0108   for (int theRing = 0; theRing < nLaserRings; theRing++) {
0109     // loop over the LaserBeams
0110     for (int theBeam = 0; theBeam < nLaserBeams; theBeam++) {
0111       // code for forward and backward beam
0112       // calculate the right phi for the current beam
0113       G4double LaserPositionPhi = LaserPhi0 + G4double(theBeam * G4double(G4double(2 * M_PI) / nLaserBeams));
0114
0115       // calculate x and y position for the current beam
0116       G4double LaserPositionX = cos(LaserPositionPhi) * LaserRingRadius[theRing];
0117       G4double LaserPositionY = sin(LaserPositionPhi) * LaserRingRadius[theRing];
0118
0119       // loop over all the particles in one beam
0120       for (int theParticle = 0; theParticle < thenParticle; theParticle++) {
0121         // get randomnumbers  and calculate the position
0122         CLHEP::RandGaussQ aGaussObjX(*theDRand48Engine, LaserPositionX, LaserRingSigmaX[theRing]);
0123         CLHEP::RandGaussQ aGaussObjY(*theDRand48Engine, LaserPositionY, LaserRingSigmaY[theRing]);
0124
0125         G4double theXPosition = aGaussObjX.fire();
0126         G4double theYPosition = aGaussObjY.fire();
0127         G4double theZPosition = LaserPositionZ;
0128
0129         // set the properties of the newly created particle
0130         theParticleGun->SetParticleDefinition(theOpticalPhoton);
0131         theParticleGun->SetParticleTime(0.0 * ns);
0132         theParticleGun->SetParticlePosition(G4ThreeVector(theXPosition, theYPosition, theZPosition));
0133         theParticleGun->SetParticleEnergy(thePhotonEnergy);
0134
0135         // loop over both directions of the beam
0136         for (int theDirection = 0; theDirection < 2; theDirection++) {
0137           // shoot in both beam directions ...
0138           if (theDirection == 0)  // shoot in forward direction (+z)
0139           {
0140             theParticleGun->SetParticleMomentumDirection(G4ThreeVector(0.0, 0.0, 1.0));
0141             // set the polarization
0142             setOptPhotonPolar(90.0);
0143             // generate the particle
0144             theParticleGun->GeneratePrimaryVertex(myEvent);
0145           }
0146
0147           if (theDirection == 1)  // shoot in backward direction (-z)
0148           {
0149             theParticleGun->SetParticleMomentumDirection(G4ThreeVector(0.0, 0.0, -1.0));
0150             // set the polarization
0151             setOptPhotonPolar(90.0);
0152             // generate the particle
0153             theParticleGun->GeneratePrimaryVertex(myEvent);
0154           }
0155         }  // end loop over both beam directions
0156       }    // end loop over particles in beam
0157     }      // end loop over beams
0158   }        // end loop over rings
0159 }
0160
0161 void LaserBeamsTEC2::setOptPhotonPolar(G4double Angle) {
0162   /* *********************************************************************** */
0163   /*   to get optical processes working properly, you have to make sure      *
0164    *   that the photon polarisation is defined.                              */
0165   /* *********************************************************************** */
0166
0167   // first check if we have an optical photon
0168   if (theParticleGun->GetParticleDefinition()->GetParticleName() != "opticalphoton") {
0169     edm::LogWarning("SimLaserAlignment:LaserBeamsTEC2")
0170         << "<LaserBeamsTEC2::setOptPhotonPolar()>: WARNING! The ParticleGun is "
0171            "not an optical photon";
0172     return;
0173   }
0174
0175   //   G4cout << "  AC1CMS: The ParticleGun is an " <<
0176   //   theParticleGun->GetParticleDefinition()->GetParticleName();
0177   G4ThreeVector normal(1.0, 0.0, 0.0);
0178   G4ThreeVector kphoton = theParticleGun->GetParticleMomentumDirection();
0179   G4ThreeVector product = normal.cross(kphoton);
0180   G4double modul2 = product * product;
0181
0182   G4ThreeVector e_perpendicular(0.0, 0.0, 1.0);
0183
0184   if (modul2 > 0.0) {
0185     e_perpendicular = (1.0 / sqrt(modul2)) * product;
0186   }
0187
0188   G4ThreeVector e_parallel = e_perpendicular.cross(kphoton);
0189
0190   G4ThreeVector polar = cos(Angle) * e_parallel + sin(Angle) * e_perpendicular;
0191
0192   //   G4cout << ", the polarization = " << polar << G4endl;
0193   theParticleGun->SetParticlePolarization(polar);
0194 }