/data/refman/pasoursint/CMSSW_5_3_4/src/GeneratorInterface/HiGenCommon/plugins/BetaBoostEvtVtxGenerator.cc

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// $Id: BetaBoostEvtVtxGenerator.cc,v 1.2 2012/09/06 20:41:40 lixu Exp $
/*
________________________________________________________________________

 BetaBoostEvtVtxGenerator

 Smear vertex according to the Beta function on the transverse plane
 and a Gaussian on the z axis. It allows the beam to have a crossing
 angle (slopes dxdz and dydz).

 Based on GaussEvtVtxGenerator
 implemented by Francisco Yumiceva (yumiceva@fnal.gov)

 FERMILAB
 2006
________________________________________________________________________
*/

//lingshan: add beta for z-axis boost

//#include "IOMC/EventVertexGenerators/interface/BetafuncEvtVtxGenerator.h"

#include "FWCore/Framework/interface/Event.h"
#include "FWCore/Utilities/interface/Exception.h"
#include "FWCore/ParameterSet/interface/ParameterSet.h"

#include "FWCore/Framework/interface/EDProducer.h"
#include "FWCore/Utilities/interface/InputTag.h"
#include "FWCore/ServiceRegistry/interface/Service.h"
#include "FWCore/Utilities/interface/RandomNumberGenerator.h"
#include "SimDataFormats/GeneratorProducts/interface/HepMCProduct.h"

#include "CLHEP/Random/RandGaussQ.h"
#include "CLHEP/Units/GlobalSystemOfUnits.h"
#include "CLHEP/Units/GlobalPhysicalConstants.h"
//#include "CLHEP/Vector/ThreeVector.h"
#include "HepMC/SimpleVector.h"
#include "TMatrixD.h"

#include <iostream>

using namespace edm;
using namespace std;
using namespace CLHEP;

class RandGaussQ;


class BetaBoostEvtVtxGenerator : public edm::EDProducer{
public:
  BetaBoostEvtVtxGenerator(const edm::ParameterSet & p);
  virtual ~BetaBoostEvtVtxGenerator();

  //virtual CLHEP::Hep3Vector * newVertex();
  virtual HepMC::FourVector* newVertex() ;
  virtual void produce( edm::Event&, const edm::EventSetup& );
  virtual TMatrixD* GetInvLorentzBoost();


  void sigmaZ(double s=1.0);

  void X0(double m=0) { fX0=m; }
  void Y0(double m=0) { fY0=m; }
  void Z0(double m=0) { fZ0=m; }

  void Phi(double m=0) { phi_=m; }
  void Alpha(double m=0) { alpha_=m; }
  void Beta(double m=0) { beta_=m; }

  void betastar(double m=0) { fbetastar=m; }
  void emittance(double m=0) { femittance=m; }

  double BetaFunction(double z, double z0);
  CLHEP::HepRandomEngine& getEngine();

private:
  BetaBoostEvtVtxGenerator(const BetaBoostEvtVtxGenerator &p);
  BetaBoostEvtVtxGenerator&  operator = (const BetaBoostEvtVtxGenerator & rhs );

  double alpha_, phi_;
  //TMatrixD boost_;
  double beta_;
  double fX0, fY0, fZ0;
  double fSigmaZ;
  //double fdxdz, fdydz;
  double fbetastar, femittance;
  double falpha;

  HepMC::FourVector*       fVertex ;
  TMatrixD *boost_;
  double fTimeOffset;
  
  CLHEP::HepRandomEngine*  fEngine;
  edm::InputTag            sourceLabel;

  CLHEP::RandGaussQ*  fRandom ;

};


BetaBoostEvtVtxGenerator::BetaBoostEvtVtxGenerator(const edm::ParameterSet & p ):
  fVertex(0), boost_(0), fTimeOffset(0), fEngine(0),
  sourceLabel(p.getParameter<edm::InputTag>("src"))
{ 
  
  edm::Service<edm::RandomNumberGenerator> rng;

  if ( ! rng.isAvailable()) {
    
    throw cms::Exception("Configuration")
      << "The BaseEvtVtxGenerator requires the RandomNumberGeneratorService\n"
      "which is not present in the configuration file.  You must add the service\n"
      "in the configuration file or remove the modules that require it.";
  }

  CLHEP::HepRandomEngine& engine = rng->getEngine();
  fEngine = &engine;
  fRandom = new CLHEP::RandGaussQ(getEngine());

  fX0 =        p.getParameter<double>("X0")*cm;
  fY0 =        p.getParameter<double>("Y0")*cm;
  fZ0 =        p.getParameter<double>("Z0")*cm;
  fSigmaZ =    p.getParameter<double>("SigmaZ")*cm;
  alpha_ =     p.getParameter<double>("Alpha")*radian;
  phi_ =       p.getParameter<double>("Phi")*radian;
  fbetastar =  p.getParameter<double>("BetaStar")*cm;
  femittance = p.getParameter<double>("Emittance")*cm; // this is not the normalized emittance
  fTimeOffset = p.getParameter<double>("TimeOffset")*ns*c_light; // HepMC time units are mm
  beta_=p.getParameter<double>("Beta"); 
  if (fSigmaZ <= 0) {
          throw cms::Exception("Configuration")
                  << "Error in BetaBoostEvtVtxGenerator: "
                  << "Illegal resolution in Z (SigmaZ is negative)";
  }

  produces<bool>(); 
  
}

BetaBoostEvtVtxGenerator::~BetaBoostEvtVtxGenerator() 
{
  delete fVertex ;
  if (boost_ != 0 ) delete boost_;
  delete fRandom; 
}

CLHEP::HepRandomEngine& BetaBoostEvtVtxGenerator::getEngine(){
  return *fEngine;
}


//Hep3Vector* BetaBoostEvtVtxGenerator::newVertex() {
HepMC::FourVector* BetaBoostEvtVtxGenerator::newVertex() {

        
        double X,Y,Z;
        
        double tmp_sigz = fRandom->fire(0., fSigmaZ);
        Z = tmp_sigz + fZ0;

        double tmp_sigx = BetaFunction(Z,fZ0); 
        // need sqrt(2) for beamspot width relative to single beam width
        tmp_sigx /= sqrt(2.0);
        X = fRandom->fire(0.,tmp_sigx) + fX0; // + Z*fdxdz ;

        double tmp_sigy = BetaFunction(Z,fZ0);
        // need sqrt(2) for beamspot width relative to single beam width
        tmp_sigy /= sqrt(2.0);
        Y = fRandom->fire(0.,tmp_sigy) + fY0; // + Z*fdydz;

        double tmp_sigt = fRandom->fire(0., fSigmaZ);
        double T = tmp_sigt + fTimeOffset; 

        if ( fVertex == 0 ) fVertex = new HepMC::FourVector();
        fVertex->set(X,Y,Z,T);
                
        return fVertex;
}

double BetaBoostEvtVtxGenerator::BetaFunction(double z, double z0)
{
        return sqrt(femittance*(fbetastar+(((z-z0)*(z-z0))/fbetastar)));

}


void BetaBoostEvtVtxGenerator::sigmaZ(double s) 
{ 
        if (s>=0 ) {
                fSigmaZ=s; 
        }
        else {
                throw cms::Exception("LogicError")
                        << "Error in BetaBoostEvtVtxGenerator::sigmaZ: "
                        << "Illegal resolution in Z (negative)";
        }
}

TMatrixD* BetaBoostEvtVtxGenerator::GetInvLorentzBoost() {

        //alpha_ = 0;
        //phi_ = 142.e-6;
//      if (boost_ != 0 ) return boost_;
        
        //boost_.ResizeTo(4,4);
        //boost_ = new TMatrixD(4,4);
        TMatrixD tmpboost(4,4);
        TMatrixD tmpboostZ(4,4);
        TMatrixD tmpboostXYZ(4,4);

        //if ( (alpha_ == 0) && (phi_==0) ) { boost_->Zero(); return boost_; }
        
        // Lorentz boost to frame where the collision is head-on
        // phi is the half crossing angle in the plane ZS
        // alpha is the angle to the S axis from the X axis in the XY plane
        
        tmpboost(0,0) = 1./cos(phi_);
        tmpboost(0,1) = - cos(alpha_)*sin(phi_);
        tmpboost(0,2) = - tan(phi_)*sin(phi_);
        tmpboost(0,3) = - sin(alpha_)*sin(phi_);
        tmpboost(1,0) = - cos(alpha_)*tan(phi_);
        tmpboost(1,1) = 1.;
        tmpboost(1,2) = cos(alpha_)*tan(phi_);
        tmpboost(1,3) = 0.;
        tmpboost(2,0) = 0.;
        tmpboost(2,1) = - cos(alpha_)*sin(phi_);
        tmpboost(2,2) = cos(phi_);
        tmpboost(2,3) = - sin(alpha_)*sin(phi_);
        tmpboost(3,0) = - sin(alpha_)*tan(phi_);
        tmpboost(3,1) = 0.;
        tmpboost(3,2) = sin(alpha_)*tan(phi_);
        tmpboost(3,3) = 1.;
       //cout<<"beta "<<beta_;
       double gama=1.0/sqrt(1-beta_*beta_);
       tmpboostZ(0,0)=gama;
       tmpboostZ(0,1)=0.;
       tmpboostZ(0,2)=-1.0*beta_*gama;
       tmpboostZ(0,3)=0.;
       tmpboostZ(1,0)=0.;
       tmpboostZ(1,1) = 1.;
       tmpboostZ(1,2)=0.;
       tmpboostZ(1,3)=0.;
       tmpboostZ(2,0)=-1.0*beta_*gama;
       tmpboostZ(2,1) = 0.;
       tmpboostZ(2,2)=gama;
       tmpboostZ(2,3) = 0.;
       tmpboostZ(3,0)=0.;
       tmpboostZ(3,1)=0.;
       tmpboostZ(3,2)=0.;
       tmpboostZ(3,3) = 1.;

       tmpboostXYZ=tmpboostZ*tmpboost;
       tmpboostXYZ.Invert();



       boost_ = new TMatrixD(tmpboostXYZ);
       boost_->Print();
        
        return boost_;
}

void BetaBoostEvtVtxGenerator::produce( Event& evt, const EventSetup& )
{
  
  
  Handle<HepMCProduct> HepMCEvt ;    
  evt.getByLabel( sourceLabel, HepMCEvt ) ;
  
  // generate new vertex & apply the shift 
  //
  HepMCEvt->applyVtxGen( newVertex() ) ;
 
  //HepMCEvt->LorentzBoost( 0., 142.e-6 );
  HepMCEvt->boostToLab( GetInvLorentzBoost(), "vertex" );
 HepMCEvt->boostToLab( GetInvLorentzBoost(), "momentum" );    
  // OK, create a (pseudo)product and put in into edm::Event
  //
  auto_ptr<bool> NewProduct(new bool(true)) ;      
 evt.put( NewProduct ) ;       
  return ;
}




#include "FWCore/Framework/interface/MakerMacros.h"
DEFINE_FWK_MODULE(BetaBoostEvtVtxGenerator);