G4ElementaryParticleCollider Class Reference

#include <G4ElementaryParticleCollider.hh>

Inheritance diagram for G4ElementaryParticleCollider:

Collaboration diagram for G4ElementaryParticleCollider:

Public Member Functions
	G4ElementaryParticleCollider ()
virtual	~G4ElementaryParticleCollider ()
void	collide (G4InuclParticle *bullet, G4InuclParticle *target, G4CollisionOutput &output)
void	setNucleusState (G4int a, G4int z)
Public Member Functions inherited from G4CascadeColliderBase
	G4CascadeColliderBase (const G4String &name, G4int verbose=0)
virtual	~G4CascadeColliderBase ()
virtual void	rescatter (G4InuclParticle *, G4KineticTrackVector *, G4V3DNucleus *, G4CollisionOutput &)
virtual void	setVerboseLevel (G4int verbose=0)
Public Member Functions inherited from G4VCascadeCollider
	G4VCascadeCollider (const G4String &name, G4int verbose=0)
virtual	~G4VCascadeCollider ()

Private Member Functions
G4int	generateMultiplicity (G4int is, G4double ekin) const
void	generateOutgoingPartTypes (G4int is, G4int mult, G4double ekin)
void	generateSCMfinalState (G4double ekin, G4double etot_scm, G4InuclElementaryParticle *particle1, G4InuclElementaryParticle *particle2)
void	generateSCMpionAbsorption (G4double etot_scm, G4InuclElementaryParticle *particle1, G4InuclElementaryParticle *particle2)
void	generateSCMmuonAbsorption (G4double etot_scm, G4InuclElementaryParticle *particle1, G4InuclElementaryParticle *particle2)
void	generateSCMpionNAbsorption (G4double etot_scm, G4InuclElementaryParticle *particle1, G4InuclElementaryParticle *particle2)
G4bool	pionNucleonAbsorption (G4double ekin) const
G4bool	splitQuasiDeuteron (G4int qdtype)
void	fillOutgoingMasses ()
	G4ElementaryParticleCollider (const G4ElementaryParticleCollider &)
G4ElementaryParticleCollider &	operator= (const G4ElementaryParticleCollider &)

Private Attributes
G4CascadeFinalStateGenerator	fsGenerator
std::vector< G4InuclElementaryParticle >	particles
std::vector< G4LorentzVector >	scm_momentums
std::vector< G4double >	modules
std::vector< G4double >	masses
std::vector< G4double >	masses2
std::vector< G4int >	particle_kinds
G4int	nucleusA
G4int	nucleusZ

Additional Inherited Members
Protected Member Functions inherited from G4CascadeColliderBase
virtual G4bool	useEPCollider (G4InuclParticle *bullet, G4InuclParticle *target) const
virtual G4bool	inelasticInteractionPossible (G4InuclParticle *bullet, G4InuclParticle *target, G4double ekin) const
virtual G4bool	validateOutput (G4InuclParticle *bullet, G4InuclParticle *target, G4CollisionOutput &output)
virtual G4bool	validateOutput (const G4Fragment &fragment, G4CollisionOutput &output)
virtual G4bool	validateOutput (G4InuclParticle *bullet, G4InuclParticle *target, const std::vector< G4InuclElementaryParticle > &particles)
Protected Member Functions inherited from G4VCascadeCollider
virtual void	setName (const G4String &name)
Protected Attributes inherited from G4CascadeColliderBase
G4InteractionCase	interCase
G4CascadeCheckBalance *	balance
Protected Attributes inherited from G4VCascadeCollider
G4String	theName
G4int	verboseLevel

Detailed Description

Definition at line 74 of file G4ElementaryParticleCollider.hh.

Constructor & Destructor Documentation

G4ElementaryParticleCollider() [1/2]

G4ElementaryParticleCollider::G4ElementaryParticleCollider

(

)

Definition at line 138 of file G4ElementaryParticleCollider.cc.

  : G4CascadeColliderBase("G4ElementaryParticleCollider"),
    nucleusA(0), nucleusZ(0) {;}

~G4ElementaryParticleCollider()

virtual G4ElementaryParticleCollider::~G4ElementaryParticleCollider ( )

inlinevirtual

Definition at line 77 of file G4ElementaryParticleCollider.hh.

{};

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G4ElementaryParticleCollider() [2/2]

G4ElementaryParticleCollider::G4ElementaryParticleCollider ( const G4ElementaryParticleCollider &  )

private

Member Function Documentation

collide()

void G4ElementaryParticleCollider::collide ( G4InuclParticle *  bullet, G4InuclParticle *  target, G4CollisionOutput &  output  )

virtual

Implements G4VCascadeCollider.

Definition at line 144 of file G4ElementaryParticleCollider.cc.

{
  if (verboseLevel > 1)
    G4cout << " >>> G4ElementaryParticleCollider::collide" << G4endl;

  if (!useEPCollider(bullet,target)) {      // Sanity check
    G4cerr << " ElementaryParticleCollider -> can collide only particle with particle " 
           << G4endl;
    return;
  }

#ifdef G4CASCADE_DEBUG_SAMPLER
  static G4bool doPrintTables = true;   // Once and only once per job
  if (doPrintTables) {
    G4CascadeChannelTables::Print();
    doPrintTables = false;
  }
#endif

  interCase.set(bullet, target);    // To identify kind of collision

  if (verboseLevel > 1) G4cout << *bullet << G4endl << *target << G4endl;

  G4InuclElementaryParticle* particle1 =
    dynamic_cast<G4InuclElementaryParticle*>(bullet);
  G4InuclElementaryParticle* particle2 =    
    dynamic_cast<G4InuclElementaryParticle*>(target);

  if (!particle1 || !particle2) {   // Redundant with useEPCollider()
    G4cerr << " ElementaryParticleCollider -> can only collide hadrons"
           << G4endl;
    return;
  }

  if (particle1->isNeutrino() || particle2->isNeutrino()) return;

  // Check for available interaction, or pion+dibaryon special case
  if (!G4CascadeChannelTables::GetTable(interCase.hadrons()) &&
      !particle1->quasi_deutron() && !particle2->quasi_deutron()) {
    G4cerr << " ElementaryParticleCollider -> cannot collide " 
       << particle1->getDefinition()->GetParticleName() << " with "
           << particle2->getDefinition()->GetParticleName() << G4endl;
    return;
  }

  G4LorentzConvertor convertToSCM;  // Utility to handle frame manipulation
  if (particle2->nucleon() || particle2->quasi_deutron()) {
    convertToSCM.setBullet(particle1);
    convertToSCM.setTarget(particle2);
  } else {
    convertToSCM.setBullet(particle2);
    convertToSCM.setTarget(particle1);
  }

  convertToSCM.setVerbose(verboseLevel);
  convertToSCM.toTheCenterOfMass();

  G4double etot_scm = convertToSCM.getTotalSCMEnergy();

  // Generate any particle collision with nucleon
  if (particle1->nucleon() || particle2->nucleon()) {
    G4double ekin = convertToSCM.getKinEnergyInTheTRS();

    // SPECIAL:  Very low energy pions may be absorbed by a nucleon
    if (pionNucleonAbsorption(ekin)) {
      generateSCMpionNAbsorption(etot_scm, particle1, particle2);
    } else {
      generateSCMfinalState(ekin, etot_scm, particle1, particle2);
    }
  }

  // Generate pion or photon collision with quasi-deuteron
  if (particle1->quasi_deutron() || particle2->quasi_deutron()) {
    if (!G4NucleiModel::useQuasiDeuteron(particle1->type(),particle2->type()) &&
    !G4NucleiModel::useQuasiDeuteron(particle2->type(),particle1->type())) {
      G4cerr << " ElementaryParticleCollider -> can only collide pi,mu,gamma with"
         << " dibaryons " << G4endl;
      return;
    }

    if (particle1->isMuon() || particle2->isMuon()) {
      generateSCMmuonAbsorption(etot_scm, particle1, particle2);
    } else {        // Currently, pion absoprtion also handles gammas
      generateSCMpionAbsorption(etot_scm, particle1, particle2);
    }
  }    

  if (particles.empty()) {  // No final state possible, pass bullet through
    if (verboseLevel) {
      G4cerr << " ElementaryParticleCollider -> failed to collide " 
         << particle1->getMomModule() << " GeV/c " 
         << particle1->getDefinition()->GetParticleName() << " with "
         << particle2->getDefinition()->GetParticleName() << G4endl;
    }
    return;
  }

  // Convert final state back to lab frame
  G4LorentzVector mom;      // Buffer to avoid memory churn
  particleIterator ipart;
  for(ipart = particles.begin(); ipart != particles.end(); ipart++) {   
    mom = convertToSCM.backToTheLab(ipart->getMomentum());
    ipart->setMomentum(mom); 
  };
  
  // Check conservation in multibody final state
  if (verboseLevel && !validateOutput(bullet, target, particles)) {
    G4cout << " incoming particles: \n" << *particle1 << G4endl
       << *particle2 << G4endl
       << " outgoing particles: " << G4endl;
    for(ipart = particles.begin(); ipart != particles.end(); ipart++)
      G4cout << *ipart << G4endl;
    
    G4cout << " <<< Non-conservation in G4ElementaryParticleCollider"
       << G4endl;
  }
    
  std::sort(particles.begin(), particles.end(), G4ParticleLargerEkin());
  output.addOutgoingParticles(particles);
}

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fillOutgoingMasses()

void G4ElementaryParticleCollider::fillOutgoingMasses ( )

private

Definition at line 384 of file G4ElementaryParticleCollider.cc.

                                                      {
  G4int mult = particle_kinds.size();

  masses.resize(mult,0.);
  masses2.resize(mult,0.);      // Allows direct [i] setting

  for (G4int i = 0; i < mult; i++) {
    masses[i] = G4InuclElementaryParticle::getParticleMass(particle_kinds[i]);
    masses2[i] = masses[i] * masses[i];
  }
}

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generateMultiplicity()

G4int G4ElementaryParticleCollider::generateMultiplicity ( G4int  is, G4double  ekin  ) const

private

Definition at line 269 of file G4ElementaryParticleCollider.cc.

{
  G4int mul = 0;

  const G4CascadeChannel* xsecTable = G4CascadeChannelTables::GetTable(is);

  if (xsecTable) mul = xsecTable->getMultiplicity(ekin);
  else {
    G4cerr << " G4ElementaryParticleCollider: Unknown interaction channel "
       << is << " - multiplicity not generated " << G4endl;
  }

  if(verboseLevel > 3){
    G4cout << " G4ElementaryParticleCollider::generateMultiplicity: "  
           << " multiplicity = " << mul << G4endl; 
  }

  return mul;
}

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generateOutgoingPartTypes()

void G4ElementaryParticleCollider::generateOutgoingPartTypes ( G4int  is, G4int  mult, G4double  ekin  )

private

Definition at line 292 of file G4ElementaryParticleCollider.cc.

{
  particle_kinds.clear();   // Initialize buffer for generation

  const G4CascadeChannel* xsecTable = G4CascadeChannelTables::GetTable(is);

  if (xsecTable)
    xsecTable->getOutgoingParticleTypes(particle_kinds, mult, ekin);
  else {
    G4cerr << " G4ElementaryParticleCollider: Unknown interaction channel "
       << is << " - outgoing kinds not generated " << G4endl;
  }

  return;
}

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generateSCMfinalState()

void G4ElementaryParticleCollider::generateSCMfinalState ( G4double  ekin, G4double  etot_scm, G4InuclElementaryParticle *  particle1, G4InuclElementaryParticle *  particle2  )

private

Definition at line 311 of file G4ElementaryParticleCollider.cc.

                                                                   {
  if (verboseLevel > 2) {
    G4cout << " >>> G4ElementaryParticleCollider::generateSCMfinalState" 
           << G4endl;
  }

  fsGenerator.SetVerboseLevel(verboseLevel);

  const G4int itry_max = 10;

  G4int type1 = particle1->type();
  G4int type2 = particle2->type();

  G4int is = type1 * type2;

  if (verboseLevel > 3) G4cout << " is " << is << G4endl;

  G4int multiplicity = 0;
  G4bool generate = true;

  G4int itry = 0;
  while (generate && itry++ < itry_max) {  /* Loop checking 08.06.2015 MHK */
    particles.clear();      // Initialize buffers for this event
    particle_kinds.clear();

    // Generate list of final-state particles
    multiplicity = generateMultiplicity(is, ekin);

    generateOutgoingPartTypes(is, multiplicity, ekin);
    if (particle_kinds.empty()) {
      if (verboseLevel > 3) {
    G4cout << " generateOutgoingPartTypes failed mult " << multiplicity
           << G4endl;
      }
      continue;
    }

    fillOutgoingMasses();   // Fill mass buffer from particle types

    // Attempt to produce final state kinematics
    fsGenerator.Configure(particle1, particle2, particle_kinds);
    generate = !fsGenerator.Generate(etot_scm, masses, scm_momentums);
  } // while (generate) 

  if (itry >= itry_max) {       // Unable to generate valid final state
    if (verboseLevel > 2)
      G4cout << " generateSCMfinalState failed " << itry << " attempts"
         << G4endl;
    return;
  }

  // Store generated momenta into outgoing particles

  particles.resize(multiplicity);       // Preallocate buffer
  for (G4int i=0; i<multiplicity; i++) {
    particles[i].fill(scm_momentums[i], particle_kinds[i],
              G4InuclParticle::EPCollider);
  }

  if (verboseLevel > 3) {
    G4cout << " <<< G4ElementaryParticleCollider::generateSCMfinalState"
       << G4endl;
  }

  return;   // Particles buffer filled
}

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generateSCMmuonAbsorption()

void G4ElementaryParticleCollider::generateSCMmuonAbsorption ( G4double  etot_scm, G4InuclElementaryParticle *  particle1, G4InuclElementaryParticle *  particle2  )

private

Definition at line 446 of file G4ElementaryParticleCollider.cc.

{
  if (verboseLevel > 3)
    G4cout << " >>> G4ElementaryParticleCollider::generateSCMmuonAbsorption"
           << G4endl;

  // A phase space generator is required for the 3-body final state

  particles.clear();            // Initialize buffers for this event
  particles.resize(3);

  scm_momentums.clear();
  scm_momentums.resize(3);

  particle_kinds.clear();

  G4int type1 = particle1->type();
  G4int type2 = particle2->type();

  if (type1 != muonMinus) return;   // Sanity check, only mu- absorption

  // Ensure that absportion is valid (charge conservable)
  if (!G4NucleiModel::useQuasiDeuteron(type1, type2)) {
    G4cerr << " mu- absorption: "
       << particle1->getDefinition()->GetParticleName() << " + "
       << particle2->getDefinition()->GetParticleName() << " -> ?"
       << G4endl;
    return;
  }

  if (!splitQuasiDeuteron(type2)) return;   // Get constituents of [NN]
  particle_kinds.push_back(mnu);
  
  fillOutgoingMasses();

  G4GDecay3 breakup(etot_scm, masses[0], masses[1], masses[2]);
  std::vector<G4ThreeVector> theMomenta = breakup.GetThreeBodyMomenta();

  if (theMomenta.empty()) {
    G4cerr << " generateSCMmuonAbsorption: GetThreeBodyMomenta() failed"
       << " for " << type2 << " dibaryon" << G4endl;
    particle_kinds.clear();
    masses.clear();
    return;
  }

  for (size_t i=0; i<3; i++) {
    scm_momentums[i].setVectM(theMomenta[i], masses[i]);
    particles[i].fill(scm_momentums[i], particle_kinds[i], G4InuclParticle::EPCollider);
  }
} 

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generateSCMpionAbsorption()

void G4ElementaryParticleCollider::generateSCMpionAbsorption ( G4double  etot_scm, G4InuclElementaryParticle *  particle1, G4InuclElementaryParticle *  particle2  )

private

Definition at line 401 of file G4ElementaryParticleCollider.cc.

                                                               {
  if (verboseLevel > 3)
    G4cout << " >>> G4ElementaryParticleCollider::generateSCMpionAbsorption" 
       << G4endl;

  particles.clear();        // Initialize buffers for this event
  particles.resize(2);

  particle_kinds.clear();

  G4int type1 = particle1->type();
  G4int type2 = particle2->type();

  // Ensure that absportion is valid (charge conservable)
  if (!G4NucleiModel::useQuasiDeuteron(type1, type2)) {
    G4cerr << " pion absorption: "
       << particle1->getDefinition()->GetParticleName() << " + "
       << particle2->getDefinition()->GetParticleName() << " -> ?"
       << G4endl;
    return;
  }

  if (!splitQuasiDeuteron(type2)) return;   // Get constituents of [NN]

  fillOutgoingMasses();

  G4double a = 0.5 * (etot_scm * etot_scm - masses2[0] - masses2[1]);

  G4double pmod = std::sqrt((a*a - masses2[0]*masses2[1])
                / (etot_scm*etot_scm) );
  G4LorentzVector mom1 = generateWithRandomAngles(pmod, masses[0]);
  G4LorentzVector mom2;
  mom2.setVectM(-mom1.vect(), masses[1]);

  particles[0].fill(mom1, particle_kinds[0], G4InuclParticle::EPCollider);
  particles[1].fill(mom2, particle_kinds[1], G4InuclParticle::EPCollider);
}

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generateSCMpionNAbsorption()

void G4ElementaryParticleCollider::generateSCMpionNAbsorption ( G4double  etot_scm, G4InuclElementaryParticle *  particle1, G4InuclElementaryParticle *  particle2  )

private

Definition at line 504 of file G4ElementaryParticleCollider.cc.

                                                               {
  if (verboseLevel > 3)
    G4cout << " >>> G4ElementaryParticleCollider::generateSCMpionNAbsorption" 
       << G4endl;

  particles.clear();        // Initialize buffers for this event
  particles.resize(1);

  particle_kinds.clear();

  G4int type1 = particle1->type();
  G4int type2 = particle2->type();

  // Ensure that single-nucleon absportion is valid (charge exchangeable)
  if ((type1*type2 != pim*pro && type1*type2 != pip*neu)) {
    G4cerr << " pion-nucleon absorption: "
       << particle1->getDefinition()->GetParticleName() << " + "
       << particle2->getDefinition()->GetParticleName() << " -> ?"
       << G4endl;
    return;
  }

  // Get outgoing nucleon type using charge exchange
  // Proton code is 1, neutron code is 2, so 3-# swaps them
  G4int ntype = (particle2->nucleon() ? type2 : type1);
  G4int outType = 3 - ntype;
  particle_kinds.push_back(outType);

  fillOutgoingMasses();

  // Get mass of residual nucleus (2-ntype = 1 for proton, 0 for neutron)
  G4double mRecoil =
    G4InuclNuclei::getNucleiMass(nucleusA-1, nucleusZ-(2-ntype));
  G4double mRecoil2 = mRecoil*mRecoil;

  // Recompute Ecm to include nucleus (for recoil kinematics)
  G4LorentzVector piN4 = particle1->getMomentum() + particle2->getMomentum();
  G4LorentzVector vsum(0.,0.,0.,mRecoil);
  vsum += piN4;

  // Two-body kinematics (nucleon against nucleus) in overall CM system
  G4double esq_scm = vsum.m2();
  G4double a = 0.5 * (esq_scm - masses2[0] - mRecoil2);

  G4double pmod = std::sqrt((a*a - masses2[0]*mRecoil2) / esq_scm );
  G4LorentzVector mom1 = generateWithRandomAngles(pmod, masses[0]);

  if (verboseLevel > 3) {
    G4cout << " outgoing type " << outType << " recoiling on nuclear mass "
       << mRecoil << "\n a " << a << " p " << pmod << " Ekin "
       << mom1.e()-masses[0] << G4endl;
  }

  mom1.boost(-piN4.boostVector());  // Boost into CM of pi-N collision

  if (verboseLevel > 3) {
    G4cout << " in original pi-N frame p(SCM) " << mom1.rho() << " Ekin "
       << mom1.e()-masses[0] << G4endl;
  }

  // Fill only the ejected nucleon
  particles[0].fill(mom1, particle_kinds[0], G4InuclParticle::EPCollider);
}

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operator=()

G4ElementaryParticleCollider& G4ElementaryParticleCollider::operator= ( const G4ElementaryParticleCollider &  )

private

pionNucleonAbsorption()

G4bool G4ElementaryParticleCollider::pionNucleonAbsorption ( G4double  ekin ) const

private

Definition at line 574 of file G4ElementaryParticleCollider.cc.

                                                                       {
  if (verboseLevel > 3)
    G4cout << " >>> G4ElementaryParticleCollider::pionNucleonAbsorption ?"
           << " ekin " << ekin << " is " << interCase.hadrons() << G4endl;

  // Absorption occurs with specified probability
  const G4double absProb = G4CascadeParameters::piNAbsorption();

  // Absorption occurs only for pi- p -> n, or pi+ n -> p
  // Restrict to "very slow" pions, to allow for some normal scattering
  return ((interCase.hadrons() == pim*pro ||
       interCase.hadrons() == pip*neu)
      && (ekin < 0.05)      // 50 MeV kinetic energy or less
      && (G4UniformRand() < absProb)
      );
}

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setNucleusState()

void G4ElementaryParticleCollider::setNucleusState ( G4int  a, G4int  z  )

inline

Definition at line 82 of file G4ElementaryParticleCollider.hh.

                                         {  // Nucleus to use for recoil
    nucleusA = a; nucleusZ = z;
  }

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splitQuasiDeuteron()

G4bool G4ElementaryParticleCollider::splitQuasiDeuteron ( G4int  qdtype )

private

Definition at line 594 of file G4ElementaryParticleCollider.cc.

                                                                    {
  if (qdtype != diproton && qdtype != unboundPN && qdtype != dineutron) {
    G4cerr << " type " << qdtype << " not dibaryon!" << G4endl;
    return false;
  }

  G4int b2 = qdtype % 10;   // Dibaryon codes are 1ab (a=1,2; b=1,2)
  G4int b1 = (qdtype/10) % 10;

  particle_kinds.push_back(b1);
  particle_kinds.push_back(b2);

  return true;
}

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Member Data Documentation

fsGenerator

G4CascadeFinalStateGenerator G4ElementaryParticleCollider::fsGenerator

private

Definition at line 117 of file G4ElementaryParticleCollider.hh.

masses

std::vector<G4double> G4ElementaryParticleCollider::masses

private

Definition at line 123 of file G4ElementaryParticleCollider.hh.

masses2

std::vector<G4double> G4ElementaryParticleCollider::masses2

private

Definition at line 124 of file G4ElementaryParticleCollider.hh.

modules

std::vector<G4double> G4ElementaryParticleCollider::modules

private

Definition at line 122 of file G4ElementaryParticleCollider.hh.

nucleusA

G4int G4ElementaryParticleCollider::nucleusA

private

Definition at line 128 of file G4ElementaryParticleCollider.hh.

nucleusZ

G4int G4ElementaryParticleCollider::nucleusZ

private

Definition at line 128 of file G4ElementaryParticleCollider.hh.

particle_kinds

std::vector<G4int> G4ElementaryParticleCollider::particle_kinds

private

Definition at line 125 of file G4ElementaryParticleCollider.hh.

particles

std::vector<G4InuclElementaryParticle> G4ElementaryParticleCollider::particles

private

Definition at line 120 of file G4ElementaryParticleCollider.hh.

scm_momentums

std::vector<G4LorentzVector> G4ElementaryParticleCollider::scm_momentums

private

Definition at line 121 of file G4ElementaryParticleCollider.hh.

---

The documentation for this class was generated from the following files:

• G4ElementaryParticleCollider.hh
• G4ElementaryParticleCollider.cc