genie::DMELEventGenerator Class Reference

Generates values for the kinematic variables describing DMEL neutrino interaction events. Is a concrete implementation of the EventRecordVisitorI interface. More...

#include <DMELEventGenerator.h>

Inheritance diagram for genie::DMELEventGenerator:

Collaboration diagram for genie::DMELEventGenerator:

Public Member Functions
	DMELEventGenerator ()
	DMELEventGenerator (string config)
	~DMELEventGenerator ()
void	ProcessEventRecord (GHepRecord *event_rec) const
void	Configure (const Registry &config)
void	Configure (string config)
Public Member Functions inherited from genie::EventRecordVisitorI
virtual	~EventRecordVisitorI ()
Public Member Functions inherited from genie::Algorithm
virtual	~Algorithm ()
virtual void	FindConfig (void)
virtual const Registry &	GetConfig (void) const
Registry *	GetOwnedConfig (void)
virtual const AlgId &	Id (void) const
	Get algorithm ID.
virtual AlgStatus_t	GetStatus (void) const
	Get algorithm status.
virtual bool	AllowReconfig (void) const
virtual AlgCmp_t	Compare (const Algorithm *alg) const
	Compare with input algorithm.
virtual void	SetId (const AlgId &id)
	Set algorithm ID.
virtual void	SetId (string name, string config)
const Algorithm *	SubAlg (const RgKey &registry_key) const
void	AdoptConfig (void)
void	AdoptSubstructure (void)
virtual void	Print (ostream &stream) const
	Print algorithm info.

Private Member Functions
void	LoadConfig (void)
double	ComputeMaxXSec (const Interaction *in) const
void	AddTargetNucleusRemnant (GHepRecord *evrec) const
	add a recoiled nucleus remnant

Private Attributes
double	fEb
const NuclearModelI *	fNuclModel
	nuclear model
double	fMinAngleEM
DMELEvGen_BindingMode_t	fHitNucleonBindingMode
int	fMaxXSecNucleonThrows

Additional Inherited Members
Static Public Member Functions inherited from genie::Algorithm
static string	BuildParamVectKey (const std::string &comm_name, unsigned int i)
static string	BuildParamVectSizeKey (const std::string &comm_name)
static string	BuildParamMatKey (const std::string &comm_name, unsigned int i, unsigned int j)
static string	BuildParamMatRowSizeKey (const std::string &comm_name)
static string	BuildParamMatColSizeKey (const std::string &comm_name)
Protected Member Functions inherited from genie::KineGeneratorWithCache
	KineGeneratorWithCache ()
	KineGeneratorWithCache (string name)
	KineGeneratorWithCache (string name, string config)
	~KineGeneratorWithCache ()
virtual double	ComputeMaxXSec (const Interaction *in, const int nkey) const
virtual double	MaxXSec (GHepRecord *evrec, const int nkey=0) const
virtual double	FindMaxXSec (const Interaction *in, const int nkey=0) const
virtual void	CacheMaxXSec (const Interaction *in, double xsec, const int nkey=0) const
virtual double	Energy (const Interaction *in) const
virtual CacheBranchFx *	AccessCacheBranch (const Interaction *in, const int nkey=0) const
virtual void	AssertXSecLimits (const Interaction *in, double xsec, double xsec_max) const
Protected Member Functions inherited from genie::EventRecordVisitorI
	EventRecordVisitorI ()
	EventRecordVisitorI (string name)
	EventRecordVisitorI (string name, string config)
Protected Member Functions inherited from genie::Algorithm
	Algorithm ()
	Algorithm (string name)
	Algorithm (string name, string config)
void	Initialize (void)
void	DeleteConfig (void)
void	DeleteSubstructure (void)
Registry *	ExtractLocalConfig (const Registry &in) const
Registry *	ExtractLowerConfig (const Registry &in, const string &alg_key) const
	Split an incoming configuration Registry into a block valid for the sub-algo identified by alg_key.
template<class T>
bool	GetParam (const RgKey &name, T &p, bool is_top_call=true) const
template<class T>
bool	GetParamDef (const RgKey &name, T &p, const T &def) const
template<class T>
int	GetParamVect (const std::string &comm_name, std::vector< T > &v, bool is_top_call=true) const
	Handle to load vectors of parameters.
int	GetParamVectKeys (const std::string &comm_name, std::vector< RgKey > &k, bool is_top_call=true) const
template<class T>
int	GetParamMat (const std::string &comm_name, TMatrixT< T > &mat, bool is_top_call=true) const
	Handle to load matrix of parameters.
template<class T>
int	GetParamMatSym (const std::string &comm_name, TMatrixTSym< T > &mat, bool is_top_call=true) const
int	GetParamMatKeys (const std::string &comm_name, std::vector< RgKey > &k, bool is_top_call=true) const
int	AddTopRegistry (Registry *rp, bool owns=true)
	add registry with top priority, also update ownership
int	AddLowRegistry (Registry *rp, bool owns=true)
	add registry with lowest priority, also update ownership
int	MergeTopRegistry (const Registry &r)
int	AddTopRegisties (const vector< Registry * > &rs, bool owns=false)
	Add registries with top priority, also udated Ownerships.
Protected Attributes inherited from genie::KineGeneratorWithCache
const XSecAlgorithmI *	fXSecModel
double	fSafetyFactor
	ComputeMaxXSec -> ComputeMaxXSec * fSafetyFactor.
std::vector< double >	vSafetyFactors
	MaxXSec -> MaxXSec * fSafetyFactors[nkey].
int	fNumOfSafetyFactors
	Number of given safety factors.
std::vector< string >	vInterpolatorTypes
	Type of interpolator for each key in a branch.
int	fNumOfInterpolatorTypes
	Number of given interpolators types.
double	fMaxXSecDiffTolerance
	max{100*(xsec-maxxsec)/.5*(xsec+maxxsec)} if xsec>maxxsec
double	fEMin
	min E for which maxxsec is cached - forcing explicit calc.
bool	fGenerateUniformly
	uniform over allowed phase space + event weight?
Protected Attributes inherited from genie::Algorithm
bool	fAllowReconfig
bool	fOwnsSubstruc
	true if it owns its substructure (sub-algs,...)
AlgId	fID
	algorithm name and configuration set
vector< Registry * >	fConfVect
vector< bool >	fOwnerships
	ownership for every registry in fConfVect
AlgStatus_t	fStatus
	algorithm execution status
AlgMap *	fOwnedSubAlgMp
	local pool for owned sub-algs (taken out of the factory pool)

Detailed Description

Generates values for the kinematic variables describing DMEL neutrino interaction events. Is a concrete implementation of the EventRecordVisitorI interface.

Author

Andrew Furmanski

Created:\n August 04, 2014

License:\n Copyright (c) 2003-2025, The GENIE Collaboration

For the full text of the license visit http://copyright.genie-mc.org

Definition at line 34 of file DMELEventGenerator.h.

Constructor & Destructor Documentation

DMELEventGenerator() [1/2]

DMELEventGenerator::DMELEventGenerator

(

)

Definition at line 50 of file DMELEventGenerator.cxx.

                                       :
    KineGeneratorWithCache("genie::DMELEventGenerator")
{
 
}

References genie::KineGeneratorWithCache::KineGeneratorWithCache().

DMELEventGenerator() [2/2]

DMELEventGenerator::DMELEventGenerator

(

string

config

)

Definition at line 56 of file DMELEventGenerator.cxx.

                                                    :
    KineGeneratorWithCache("genie::DMELEventGenerator", config)
{
 
}

References genie::KineGeneratorWithCache::KineGeneratorWithCache().

~DMELEventGenerator()

DMELEventGenerator::~DMELEventGenerator

(

)

Definition at line 62 of file DMELEventGenerator.cxx.

{
 
}

Member Function Documentation

AddTargetNucleusRemnant()

void DMELEventGenerator::AddTargetNucleusRemnant ( GHepRecord * evrec ) const

private

add a recoiled nucleus remnant

Definition at line 284 of file DMELEventGenerator.cxx.

{
    // add the remnant nuclear target at the GHEP record
 
    LOG("DMELEvent", pINFO) << "Adding final state nucleus";
 
    double Px = 0;
    double Py = 0;
    double Pz = 0;
    double E  = 0;
 
    GHepParticle * nucleus = evrec->TargetNucleus();
    bool have_nucleus = nucleus != 0;
    if (!have_nucleus) return;
 
    int A = nucleus->A();
    int Z = nucleus->Z();
 
    int fd = nucleus->FirstDaughter();
    int ld = nucleus->LastDaughter();
 
    for(int id = fd; id <= ld; id++) {
 
        // compute A,Z for final state nucleus & get its PDG code and its mass
        GHepParticle * particle = evrec->Particle(id);
        assert(particle);
        int  pdgc = particle->Pdg();
        bool is_p  = pdg::IsProton (pdgc);
        bool is_n  = pdg::IsNeutron(pdgc);
 
        if (is_p) Z--;
        if (is_p || is_n) A--;
 
        Px += particle->Px();
        Py += particle->Py();
        Pz += particle->Pz();
        E  += particle->E();
 
    }//daughters
 
    TParticlePDG * remn = 0;
    int ipdgc = pdg::IonPdgCode(A, Z);
    remn = PDGLibrary::Instance()->Find(ipdgc);
    if(!remn) {
        LOG("HadronicVtx", pFATAL)
            << "No particle with [A = " << A << ", Z = " << Z
            << ", pdgc = " << ipdgc << "] in PDGLibrary!";
        assert(remn);
    }
 
    double Mi = nucleus->Mass();
    Px *= -1;
    Py *= -1;
    Pz *= -1;
    E = Mi-E;
 
    // Add the nucleus to the event record
    LOG("DMELEvent", pINFO)
        << "Adding nucleus [A = " << A << ", Z = " << Z
        << ", pdgc = " << ipdgc << "]";
 
    int imom = evrec->TargetNucleusPosition();
    evrec->AddParticle(
            ipdgc,kIStStableFinalState, imom,-1,-1,-1, Px,Py,Pz,E, 0,0,0,0);
 
    LOG("DMELEvent", pINFO) << "Done";
    LOG("DMELEvent", pINFO) << *evrec;
}

References genie::GHepParticle::A(), genie::GHepRecord::AddParticle(), genie::GHepParticle::E(), genie::PDGLibrary::Find(), genie::GHepParticle::FirstDaughter(), genie::PDGLibrary::Instance(), genie::pdg::IonPdgCode(), genie::pdg::IsNeutron(), genie::pdg::IsProton(), genie::kIStStableFinalState, genie::GHepParticle::LastDaughter(), LOG, genie::GHepParticle::Mass(), genie::GHepRecord::Particle(), genie::GHepParticle::Pdg(), pFATAL, pINFO, genie::GHepParticle::Px(), genie::GHepParticle::Py(), genie::GHepParticle::Pz(), genie::GHepRecord::TargetNucleus(), genie::GHepRecord::TargetNucleusPosition(), and genie::GHepParticle::Z().

Referenced by ProcessEventRecord().

ComputeMaxXSec()

double DMELEventGenerator::ComputeMaxXSec ( const Interaction * in ) const

privatevirtual

Implements genie::KineGeneratorWithCache.

Definition at line 404 of file DMELEventGenerator.cxx.

{
    // Computes the maximum differential cross section in the requested phase
    // space. This method overloads KineGeneratorWithCache::ComputeMaxXSec
    // method and the value is cached at a circular cache branch for retrieval
    // during subsequent event generation.
    // The computed max differential cross section does not need to be the exact
    // maximum. The number used in the rejection method will be scaled up by a
    // safety factor. But it needs to be fast.
    LOG("DMELEvent", pINFO) << "Computing maximum cross section to throw against";
 
    double xsec_max = -1;
    double dummy_Eb = 0.;
 
    // Clone the input interaction so that we can modify it a bit
    Interaction * interaction = new Interaction( *in );
    interaction->SetBit( kISkipProcessChk );
    interaction->SetBit( kISkipKinematicChk );
 
    // We'll select the max momentum and zero binding energy.
    // That should give us the nucleon with the highest xsec
    const Target& tgt = interaction->InitState().Tgt();
    // Pick a really slow nucleon to start, but not one at rest,
    // since Prob() for the Fermi gas family of models is zero
    // for a vanishing nucleon momentum
    double max_momentum = 0.010;
    double search_step = 0.1;
    const double STEP_STOP = 1e-6;
    while ( search_step > STEP_STOP ) {
      double pNi_next = max_momentum + search_step;
 
      // Set the nucleon we're using to be upstream at max energy and unbound
      fNuclModel->SetMomentum3( TVector3(0., 0., -pNi_next) );
      fNuclModel->SetRemovalEnergy( 0. );
 
      // Set the nucleon total energy to be on-shell with a quick call to
      // BindHitNucleon()
      genie::utils::BindHitNucleon(*interaction, *fNuclModel, dummy_Eb, kOnShell);
 
      // TODO: document this, won't work for spectral functions
      double dummy_w = -1.;
      double prob = fNuclModel->Prob(pNi_next, dummy_w, tgt,
        tgt.HitNucPosition());
 
      double costh0_max = genie::utils::CosTheta0Max( *interaction );
 
      if ( prob > 0. && costh0_max > -1. ) max_momentum = pNi_next;
      else search_step /= 2.;
    }
 
    {
        // Set the nucleon we're using to be upstream at max energy and unbound
        fNuclModel->SetMomentum3( TVector3(0., 0., -max_momentum) );
        fNuclModel->SetRemovalEnergy( 0. );
 
        // Set the nucleon total energy to be on-shell with a quick call to
        // BindHitNucleon()
        genie::utils::BindHitNucleon(*interaction, *fNuclModel, dummy_Eb, kOnShell);
 
        // Just a scoping block for now
        // OK, we're going to scan the COM frame angles to get the point of max xsec
        // We'll bin in solid angle, and find the maximum point
        // Then we'll bin/scan again inside that point
        // Rinse and repeat until the xsec stabilises to within some fraction of our safety factor
        const double acceptable_fraction_of_safety_factor = 0.2;
        const int max_n_layers = 100;
        const int N_theta = 10;
        const int N_phi = 10;
        double phi_at_xsec_max = -1;
        double costh_at_xsec_max = 0;
        double this_nuc_xsec_max = -1;
 
        double costh_range_min = -1.;
        double costh_range_max = genie::utils::CosTheta0Max( *interaction );
        double phi_range_min = 0.;
        double phi_range_max = 2*TMath::Pi();
        for (int ilayer = 0 ; ilayer < max_n_layers ; ilayer++) {
          double last_layer_xsec_max = this_nuc_xsec_max;
          double costh_increment = (costh_range_max-costh_range_min) / N_theta;
          double phi_increment   = (phi_range_max-phi_range_min) / N_phi;
          // Now scan through centre-of-mass angles coarsely
          for (int itheta = 0; itheta < N_theta; itheta++){
              double costh = costh_range_min + itheta * costh_increment;
              for (int iphi = 0; iphi < N_phi; iphi++) { // Scan around phi
                  double phi = phi_range_min + iphi * phi_increment;
                  // We're after an upper limit on the cross section, so just
                  // put the nucleon on-shell and call it good. The last
                  // argument is false because we've already called
                  // BindHitNucleon() above
                  double xs = genie::utils::ComputeFullDMELPXSec(interaction,
                    fNuclModel, fXSecModel, costh, phi, dummy_Eb, kOnShell, fMinAngleEM, false);
 
                  if (xs > this_nuc_xsec_max){
                      phi_at_xsec_max = phi;
                      costh_at_xsec_max = costh;
                      this_nuc_xsec_max = xs;
                  }
                  //
              } // Done with phi scan
          }// Done with centre-of-mass angles coarsely
 
          // Calculate the range for the next layer
          costh_range_min = costh_at_xsec_max - costh_increment;
          costh_range_max = costh_at_xsec_max + costh_increment;
          phi_range_min = phi_at_xsec_max - phi_increment;
          phi_range_max = phi_at_xsec_max + phi_increment;
 
          double improvement_factor = this_nuc_xsec_max/last_layer_xsec_max;
          if (ilayer && (improvement_factor-1) < acceptable_fraction_of_safety_factor * (fSafetyFactor-1)) {
            break;
          }
        }
        if (this_nuc_xsec_max > xsec_max) {
            xsec_max = this_nuc_xsec_max;
            LOG("DMELEvent", pINFO) << "best estimate for xsec_max = " << xsec_max;
        }
 
        delete interaction;
    }
    // Apply safety factor, since value retrieved from the cache might
    // correspond to a slightly different energy
    xsec_max *= fSafetyFactor;
 
#ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
    SLOG("DMELEvent", pDEBUG) << interaction->AsString();
    SLOG("DMELEvent", pDEBUG) << "Max xsec in phase space = " << max_xsec;
    SLOG("DMELEvent", pDEBUG) << "Computed using alg = " << *fXSecModel;
#endif
 
    LOG("DMELEvent", pINFO) << "Computed maximum cross section to throw against - value is " << xsec_max;
    return xsec_max;
}

References genie::Interaction::AsString(), genie::utils::BindHitNucleon(), genie::utils::ComputeFullDMELPXSec(), genie::utils::CosTheta0Max(), e, fMinAngleEM, fNuclModel, genie::KineGeneratorWithCache::fSafetyFactor, genie::KineGeneratorWithCache::fXSecModel, genie::Target::HitNucPosition(), genie::Interaction::InitState(), genie::kISkipKinematicChk, genie::kISkipProcessChk, genie::kOnShell, LOG, pDEBUG, pINFO, SLOG, and genie::InitialState::Tgt().

Configure() [1/2]

void DMELEventGenerator::Configure ( const Registry & config )

virtual

Configure the algorithm with an external registry The registry is merged with the top level registry if it is owned, Otherwise a copy of it is added with the highest priority

Reimplemented from genie::Algorithm.

Definition at line 353 of file DMELEventGenerator.cxx.

{
    Algorithm::Configure(config);
    this->LoadConfig();
}

References genie::Algorithm::Configure(), and LoadConfig().

Configure() [2/2]

void DMELEventGenerator::Configure ( string config )

virtual

Configure the algorithm from the AlgoConfigPool based on param_set string given in input An algorithm contains a vector of registries coming from different xml configuration files, which are loaded according a very precise prioriy This methods will load a number registries in order of priority: 1) "Tunable" parameter set from CommonParametes. This is loaded with the highest prioriry and it is designed to be used for tuning procedure Usage not expected from the user. 2) For every string defined in "CommonParame" the corresponding parameter set will be loaded from CommonParameter.xml 3) parameter set specified by the config string and defined in the xml file of the algorithm 4) if config is not "Default" also the Default parameter set from the same xml file will be loaded Effectively this avoids the repetion of a parameter when it is not changed in the requested configuration

Reimplemented from genie::Algorithm.

Definition at line 359 of file DMELEventGenerator.cxx.

{
    Algorithm::Configure(config);
    this->LoadConfig();
}

References genie::Algorithm::Configure(), and LoadConfig().

LoadConfig()

void DMELEventGenerator::LoadConfig ( void )

private

Definition at line 365 of file DMELEventGenerator.cxx.

{
    // Load sub-algorithms and config data to reduce the number of registry
    // lookups
        fNuclModel = 0;
 
    RgKey nuclkey = "NuclearModel";
 
    fNuclModel = dynamic_cast<const NuclearModelI *> (this->SubAlg(nuclkey));
    assert(fNuclModel);
 
    // Safety factor for the maximum differential cross section
    GetParamDef( "MaxXSec-SafetyFactor", fSafetyFactor, 1.6  ) ;
 
    // Minimum energy for which max xsec would be cached, forcing explicit
    // calculation for lower eneries
    GetParamDef( "Cache-MinEnergy", fEMin, 1.00 ) ;
    
    // Maximum allowed fractional cross section deviation from maxim cross
    // section used in rejection method
    GetParamDef( "MaxXSec-DiffTolerance", fMaxXSecDiffTolerance, 999999. ) ;
    assert(fMaxXSecDiffTolerance>=0);
 
    // Generate kinematics uniformly over allowed phase space and compute
    // an event weight?
    GetParamDef( "UniformOverPhaseSpace", fGenerateUniformly, false ) ;
 
    GetParamDef( "SF-MinAngleEMscattering", fMinAngleEM, 0. ) ;
 
    // Decide how to handle the binding energy of the initial state struck
    // nucleon
    std::string binding_mode;
    GetParamDef( "HitNucleonBindingMode", binding_mode, std::string("UseNuclearModel") );
 
    fHitNucleonBindingMode = genie::utils::StringToDMELBindingMode( binding_mode );
 
    GetParamDef( "MaxXSecNucleonThrows", fMaxXSecNucleonThrows, 800 );
}

References genie::KineGeneratorWithCache::fEMin, genie::KineGeneratorWithCache::fGenerateUniformly, fHitNucleonBindingMode, genie::KineGeneratorWithCache::fMaxXSecDiffTolerance, fMaxXSecNucleonThrows, fMinAngleEM, fNuclModel, genie::KineGeneratorWithCache::fSafetyFactor, genie::Algorithm::GetParamDef(), genie::utils::StringToDMELBindingMode(), and genie::Algorithm::SubAlg().

Referenced by Configure(), and Configure().

ProcessEventRecord()

void DMELEventGenerator::ProcessEventRecord ( GHepRecord * event_rec ) const

virtual

Implements genie::EventRecordVisitorI.

Definition at line 67 of file DMELEventGenerator.cxx.

{
    LOG("DMELEvent", pDEBUG) << "Generating QE event kinematics...";
 
    // Get the random number generators
    RandomGen * rnd = RandomGen::Instance();
 
    // Access cross section algorithm for running thread
    RunningThreadInfo * rtinfo = RunningThreadInfo::Instance();
    const EventGeneratorI * evg = rtinfo->RunningThread();
    fXSecModel = evg->CrossSectionAlg();
 
    // Get the interaction and check we are working with a nuclear target
    Interaction * interaction = evrec->Summary();
    // Skip if not a nuclear target
    if(interaction->InitState().Tgt().IsNucleus()) {
        // Skip if no hit nucleon is set
        if(! evrec->HitNucleon()) {
            LOG("DMELEvent", pFATAL) << "No hit nucleon was set";
            gAbortingInErr = true;
            exit(1);
        }
    } // is nuclear target
 
    // set the 'trust' bits
    interaction->SetBit(kISkipProcessChk);
    interaction->SetBit(kISkipKinematicChk);
 
    // Access the hit nucleon and target nucleus entries at the GHEP record
    GHepParticle * nucleon = evrec->HitNucleon();
    GHepParticle * nucleus = evrec->TargetNucleus();
    bool have_nucleus = (nucleus != 0);
 
    // Store the hit nucleon radius before computing the maximum differential
    // cross section (important when using the local Fermi gas model)
    Target* tgt = interaction->InitState().TgtPtr();
    double hitNucPos = nucleon->X4()->Vect().Mag();
    tgt->SetHitNucPosition( hitNucPos );
 
    //-- For the subsequent kinematic selection with the rejection method:
    //   Calculate the max differential cross section or retrieve it from the
    //   cache. Throw an exception and quit the evg thread if a non-positive
    //   value is found.
    //   If the kinematics are generated uniformly over the allowed phase
    //   space the max xsec is irrelevant
    double xsec_max = (fGenerateUniformly) ? -1 : this->MaxXSec(evrec);
 
    // For a composite nuclear target, check to make sure that the
    // final nucleus has a recognized PDG code
    if ( have_nucleus ) {
      // compute A,Z for final state nucleus & get its PDG code
      int nucleon_pdgc = nucleon->Pdg();
      bool is_p  = pdg::IsProton(nucleon_pdgc);
      int Z = (is_p) ? nucleus->Z()-1 : nucleus->Z();
      int A = nucleus->A() - 1;
      TParticlePDG * fnucleus = 0;
      int ipdgc = pdg::IonPdgCode(A, Z);
      fnucleus = PDGLibrary::Instance()->Find(ipdgc);
      if (!fnucleus) {
        LOG("DMELEvent", pFATAL)
            << "No particle with [A = " << A << ", Z = " << Z
            << ", pdgc = " << ipdgc << "] in PDGLibrary!";
        exit(1);
      }
    }
 
    // In the accept/reject loop, each iteration samples a new value of
    //   - the hit nucleon 3-momentum,
    //   - its binding energy (only actually used if fHitNucleonBindingMode == kUseNuclearModel)
    //   - the final lepton scattering angles in the neutrino-and-hit-nucleon COM frame
    //     (measured with respect to the velocity of the COM frame as seen in the lab frame)
    unsigned int iter = 0;
    bool accept = false;
    while (1) {
 
        iter++;
        LOG("DMELEvent", pINFO) << "Attempt #: " << iter;
        if(iter > kRjMaxIterations) {
            LOG("DMELEvent", pWARN)
                << "Couldn't select a valid (pNi, Eb, cos_theta_0, phi_0) tuple after "
                << iter << " iterations";
            evrec->EventFlags()->SetBitNumber(kKineGenErr, true);
            genie::exceptions::EVGThreadException exception;
            exception.SetReason("Couldn't select kinematics");
            exception.SwitchOnFastForward();
            throw exception;
        }
 
        // If the target is a composite nucleus, then sample an initial nucleon
        // 3-momentum and removal energy from the nuclear model.
        if ( tgt->IsNucleus() ) {
          fNuclModel->GenerateNucleon(*tgt, hitNucPos);
        }
        else {
          // Otherwise, just set the nucleon to be at rest in the lab frame and
          // unbound. Use the nuclear model to make these assignments. The call
          // to BindHitNucleon() will apply them correctly below.
          fNuclModel->SetMomentum3( TVector3(0., 0., 0.) );
          fNuclModel->SetRemovalEnergy( 0. );
        }
 
        // Put the hit nucleon off-shell (if needed) so that we can get the correct
        // value of cos_theta0_max
        genie::utils::BindHitNucleon(*interaction, *fNuclModel,
          fEb, fHitNucleonBindingMode);
 
        double cos_theta0_max = std::min(1., CosTheta0Max(*interaction));
 
        // If the allowed range of cos(theta_0) is vanishing, skip doing the
        // full differential cross section calculation (it will be zero)
        if ( cos_theta0_max <= -1. ) continue;
 
        // Pick a direction
        // NOTE: In the kPSDMELEvGen phase space used by this generator,
        // these angles are specified with respect to the velocity of the
        // probe + hit nucleon COM frame as measured in the lab frame. That is,
        // costheta = 1 means that the outgoing lepton's COM frame 3-momentum
        // points parallel to the velocity of the COM frame.
        double costheta = rnd->RndKine().Uniform(-1., cos_theta0_max); // cosine theta
        double phi = rnd->RndKine().Uniform( 2.*kPi ); // phi: [0, 2pi]
 
        // Set the "bind_nucleon" flag to false in this call to ComputeFullDMELPXSec
        // since we've already done that above
        LOG("DMELEvent", pDEBUG) << "cth0 = " << costheta << ", phi0 = " << phi;
        double xsec = genie::utils::ComputeFullDMELPXSec(interaction, fNuclModel,
          fXSecModel, costheta, phi, fEb, fHitNucleonBindingMode, fMinAngleEM, false);
 
        // select/reject event
        this->AssertXSecLimits(interaction, xsec, xsec_max);
 
        double t = xsec_max * rnd->RndKine().Rndm();
 
#ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
        LOG("DMELEvent", pDEBUG)
            << "xsec= " << xsec << ", Rnd= " << t;
#endif
        accept = (t < xsec);
 
        // If the generated kinematics are accepted, finish-up module's job
        if(accept) {
            double gQ2 = interaction->KinePtr()->Q2(false);
            LOG("DMELEvent", pINFO) << "*Selected* Q^2 = " << gQ2 << " GeV^2";
 
            // reset bits
            interaction->ResetBit(kISkipProcessChk);
            interaction->ResetBit(kISkipKinematicChk);
            interaction->ResetBit(kIAssumeFreeNucleon);
 
            // get neutrino energy at struck nucleon rest frame and the
            // struck nucleon mass (can be off the mass shell)
            const InitialState & init_state = interaction->InitState();
            double E  = init_state.ProbeE(kRfHitNucRest);
            double M = init_state.Tgt().HitNucP4().M();
            LOG("DMELKinematics", pNOTICE) << "E = " << E << ", M = "<< M;
 
            // The hadronic inv. mass is equal to the recoil nucleon on-shell mass.
            // For DMEL/Charm events it is set to be equal to the on-shell mass of
            // the generated charm baryon (Lamda_c+, Sigma_c+ or Sigma_c++)
            // Similarly for strange baryons
            //
            const XclsTag & xcls = interaction->ExclTag();
            int rpdgc = 0;
            if (xcls.IsCharmEvent()) {
                rpdgc = xcls.CharmHadronPdg();
            } else if (xcls.IsStrangeEvent()) {
                rpdgc = xcls.StrangeHadronPdg();
            } else {
                rpdgc = interaction->RecoilNucleonPdg();
            }
            assert(rpdgc);
            double gW = PDGLibrary::Instance()->Find(rpdgc)->Mass();
            LOG("DMELEvent", pNOTICE) << "Selected: W = "<< gW;
 
            // (W,Q2) -> (x,y)
            double gx=0, gy=0;
            kinematics::WQ2toXY(E,M,gW,gQ2,gx,gy);
 
            // lock selected kinematics & clear running values
            interaction->KinePtr()->SetQ2(gQ2, true);
            interaction->KinePtr()->SetW (gW,  true);
            interaction->KinePtr()->Setx (gx,  true);
            interaction->KinePtr()->Sety (gy,  true);
            interaction->KinePtr()->ClearRunningValues();
 
            // set the cross section for the selected kinematics
            evrec->SetDiffXSec(xsec, kPSDMELEvGen);
 
            TLorentzVector lepton(interaction->KinePtr()->FSLeptonP4());
            TLorentzVector outNucleon(interaction->KinePtr()->HadSystP4());
            TLorentzVector x4l(*(evrec->Probe())->X4());
 
            evrec->AddParticle(interaction->FSPrimLeptonPdg(), kIStStableFinalState,
              evrec->ProbePosition(), -1, -1, -1, interaction->KinePtr()->FSLeptonP4(), x4l);
 
            GHepStatus_t ist = (tgt->IsNucleus()) ? kIStHadronInTheNucleus : kIStStableFinalState;
            evrec->AddParticle(interaction->RecoilNucleonPdg(), ist, evrec->HitNucleonPosition(),
              -1, -1, -1, interaction->KinePtr()->HadSystP4(), x4l);
 
            // Store struck nucleon momentum and binding energy
            TLorentzVector p4ptr = interaction->InitStatePtr()->TgtPtr()->HitNucP4();
            LOG("DMELEvent",pNOTICE) << "pn: " << p4ptr.X() << ", "
              << p4ptr.Y() << ", " << p4ptr.Z() << ", " << p4ptr.E();
            nucleon->SetMomentum(p4ptr);
            nucleon->SetRemovalEnergy(fEb);
 
            // add a recoiled nucleus remnant
            this->AddTargetNucleusRemnant(evrec);
 
            break; // done
        } else { // accept throw
            LOG("DMELEvent", pDEBUG) << "Reject current throw...";
        }
 
    } // iterations - while(1) loop
    LOG("DMELEvent", pINFO) << "Done generating QE event kinematics!";
}

References genie::GHepParticle::A(), genie::GHepRecord::AddParticle(), AddTargetNucleusRemnant(), genie::KineGeneratorWithCache::AssertXSecLimits(), genie::utils::BindHitNucleon(), genie::XclsTag::CharmHadronPdg(), genie::Kinematics::ClearRunningValues(), genie::utils::ComputeFullDMELPXSec(), genie::utils::CosTheta0Max(), genie::EventGeneratorI::CrossSectionAlg(), genie::GHepRecord::EventFlags(), genie::Interaction::ExclTag(), fEb, genie::KineGeneratorWithCache::fGenerateUniformly, fHitNucleonBindingMode, genie::PDGLibrary::Find(), fMinAngleEM, fNuclModel, genie::Kinematics::FSLeptonP4(), genie::Interaction::FSPrimLeptonPdg(), genie::KineGeneratorWithCache::fXSecModel, genie::gAbortingInErr, gQ2, genie::Kinematics::HadSystP4(), genie::GHepRecord::HitNucleon(), genie::GHepRecord::HitNucleonPosition(), genie::Target::HitNucP4(), genie::Interaction::InitState(), genie::Interaction::InitStatePtr(), genie::PDGLibrary::Instance(), genie::RandomGen::Instance(), genie::RunningThreadInfo::Instance(), genie::pdg::IonPdgCode(), genie::XclsTag::IsCharmEvent(), genie::Target::IsNucleus(), genie::pdg::IsProton(), genie::XclsTag::IsStrangeEvent(), genie::kIAssumeFreeNucleon, genie::Interaction::KinePtr(), genie::kISkipKinematicChk, genie::kISkipProcessChk, genie::kIStHadronInTheNucleus, genie::kIStStableFinalState, genie::kKineGenErr, genie::constants::kPi, genie::kPSDMELEvGen, genie::kRfHitNucRest, genie::controls::kRjMaxIterations, LOG, genie::KineGeneratorWithCache::MaxXSec(), pDEBUG, genie::GHepParticle::Pdg(), pFATAL, pINFO, pNOTICE, genie::GHepRecord::Probe(), genie::InitialState::ProbeE(), genie::GHepRecord::ProbePosition(), pWARN, genie::Kinematics::Q2(), genie::Interaction::RecoilNucleonPdg(), genie::RandomGen::RndKine(), genie::RunningThreadInfo::RunningThread(), genie::GHepRecord::SetDiffXSec(), genie::Target::SetHitNucPosition(), genie::GHepParticle::SetMomentum(), genie::Kinematics::SetQ2(), genie::exceptions::EVGThreadException::SetReason(), genie::GHepParticle::SetRemovalEnergy(), genie::Kinematics::SetW(), genie::Kinematics::Setx(), genie::Kinematics::Sety(), genie::XclsTag::StrangeHadronPdg(), genie::GHepRecord::Summary(), genie::exceptions::EVGThreadException::SwitchOnFastForward(), genie::GHepRecord::TargetNucleus(), genie::InitialState::Tgt(), genie::InitialState::TgtPtr(), genie::utils::kinematics::WQ2toXY(), genie::GHepParticle::X4(), and genie::GHepParticle::Z().

Member Data Documentation

fEb

double genie::DMELEventGenerator::fEb

mutableprivate

Definition at line 51 of file DMELEventGenerator.h.

Referenced by ProcessEventRecord().

fHitNucleonBindingMode

DMELEvGen_BindingMode_t genie::DMELEventGenerator::fHitNucleonBindingMode

private

Enum that indicates which approach should be used to handle the binding energy of the struck nucleon

Definition at line 64 of file DMELEventGenerator.h.

Referenced by LoadConfig(), and ProcessEventRecord().

fMaxXSecNucleonThrows

int genie::DMELEventGenerator::fMaxXSecNucleonThrows

private

The number of nucleons to sample from the nuclear model when choosing a maximum momentum to use in ComputeMaxXSec()

Definition at line 68 of file DMELEventGenerator.h.

Referenced by LoadConfig().

fMinAngleEM

double genie::DMELEventGenerator::fMinAngleEM

mutableprivate

Definition at line 60 of file DMELEventGenerator.h.

Referenced by ComputeMaxXSec(), LoadConfig(), and ProcessEventRecord().

fNuclModel

const NuclearModelI* genie::DMELEventGenerator::fNuclModel

private

nuclear model

Definition at line 58 of file DMELEventGenerator.h.

Referenced by ComputeMaxXSec(), LoadConfig(), and ProcessEventRecord().

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

• DMELEventGenerator.h
• DMELEventGenerator.cxx