Event generator for SuSAv2 1p1h interactions. More...

#include <QELEventGeneratorSuSA.h>

Inheritance diagram for genie::QELEventGeneratorSuSA:

Public Member Functions
	QELEventGeneratorSuSA ()

	QELEventGeneratorSuSA (string config)

	~QELEventGeneratorSuSA ()

void	ProcessEventRecord (GHepRecord *event) 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. More...

virtual AlgStatus_t	GetStatus (void) const
	Get algorithm status. More...

virtual bool	AllowReconfig (void) const

virtual AlgCmp_t	Compare (const Algorithm *alg) const
	Compare with input algorithm. More...

virtual void	SetId (const AlgId &id)
	Set algorithm ID. More...

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. More...

Private Member Functions
void	LoadConfig (void)

void	AddTargetNucleusRemnant (GHepRecord *event) const

void	SelectLeptonKinematics (GHepRecord *event) const

void	GenerateNucleon (GHepRecord *event) const

double	ComputeMaxXSec (const Interaction *in) const

Private Attributes
const NuclearModelI *	fNuclModel

double	fQ3Max

bool	fForceBound

bool	fForceEbFromModel

bool	fForceFixEb

double	fEbOR

double	fEbC

const EventRecordVisitorI *	fFreeNucleonEventGenerator

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)

Protected Member Functions inherited from genie::KineGeneratorWithCache
	KineGeneratorWithCache ()

	KineGeneratorWithCache (string name)

	KineGeneratorWithCache (string name, string config)

	~KineGeneratorWithCache ()

virtual double	MaxXSec (GHepRecord *evrec) const

virtual double	FindMaxXSec (const Interaction *in) const

virtual void	CacheMaxXSec (const Interaction *in, double xsec) const

virtual double	Energy (const Interaction *in) const

virtual CacheBranchFx *	AccessCacheBranch (const Interaction *in) 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. More...

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. More...

int	GetParamVectKeys (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 More...

int	AddLowRegistry (Registry *rp, bool owns=true)
	add registry with lowest priority, also update ownership More...

int	MergeTopRegistry (const Registry &r)

int	AddTopRegisties (const vector< Registry * > &rs, bool owns=false)
	Add registries with top priority, also udated Ownerships. More...

Protected Attributes inherited from genie::KineGeneratorWithCache
const XSecAlgorithmI *	fXSecModel

double	fSafetyFactor
	maxxsec -> maxxsec * safety_factor More...

double	fMaxXSecDiffTolerance
	max{100(xsec-maxxsec)/.5(xsec+maxxsec)} if xsec>maxxsec More...

double	fEMin
	min E for which maxxsec is cached - forcing explicit calc. More...

bool	fGenerateUniformly
	uniform over allowed phase space + event weight? More...

Protected Attributes inherited from genie::Algorithm
bool	fAllowReconfig

bool	fOwnsSubstruc
	true if it owns its substructure (sub-algs,...) More...

AlgId	fID
	algorithm name and configuration set More...

vector< Registry * >	fConfVect

vector< bool >	fOwnerships
	ownership for every registry in fConfVect More...

AlgStatus_t	fStatus
	algorithm execution status More...

AlgMap *	fOwnedSubAlgMp
	local pool for owned sub-algs (taken out of the factory pool) More...

Detailed Description

Event generator for SuSAv2 1p1h interactions.

Author: Stephen Dolan <stephen.joseph.dolan cern.ch> European Organization for Nuclear Research (CERN)

Steven Gardiner <gardiner fnal.gov> Fermi National Accelerator Laboratory

Definition at line 32 of file QELEventGeneratorSuSA.h.

Constructor & Destructor Documentation

QELEventGeneratorSuSA::QELEventGeneratorSuSA ( )

Definition at line 51 of file QELEventGeneratorSuSA.cxx.

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

QELEventGeneratorSuSA::QELEventGeneratorSuSA ( string config )

Definition at line 57 of file QELEventGeneratorSuSA.cxx.

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

QELEventGeneratorSuSA::~QELEventGeneratorSuSA ( )

Definition at line 63 of file QELEventGeneratorSuSA.cxx.

 {
 
 }

Member Function Documentation

void QELEventGeneratorSuSA::AddTargetNucleusRemnant ( GHepRecord * event ) const

private

Definition at line 287 of file QELEventGeneratorSuSA.cxx.

 {
     // add the remnant nuclear target at the GHEP record
 
     LOG("QELEvent", pINFO) << "Adding final state nucleus";
 
     double Px = 0;
     double Py = 0;
     double Pz = 0;
     double E  = 0;
 
     GHepParticle * nucleus = event->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 = event->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("QELEvent", pINFO)
         << "Adding nucleus [A = " << A << ", Z = " << Z
         << ", pdgc = " << ipdgc << "]";
 
     int imom = event->TargetNucleusPosition();
     event->AddParticle(
             ipdgc,kIStStableFinalState, imom,-1,-1,-1, Px,Py,Pz,E, 0,0,0,0);
 
     LOG("QELEvent", pINFO) << "Done";
     LOG("QELEvent", pINFO) << *event;
 }

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

privatevirtual

Implements genie::KineGeneratorWithCache.

Definition at line 643 of file QELEventGeneratorSuSA.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 - do not use very small steps.
 
   double max_xsec = utils::mec::GetMaxXSecTlctl( *fXSecModel, *interaction );
 
   // Apply safety factor, since value retrieved from the cache might
   // correspond to a slightly different energy
   max_xsec *= fSafetyFactor;
 
   #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
     SLOG("QELKinematics", pDEBUG) << interaction->AsString();
     SLOG("QELKinematics", pDEBUG) << "Max xsec in phase space = " << max_xsec;
     SLOG("QELKinematics", pDEBUG) << "Computed using alg = " << *fXSecModel;
   #endif
 
   return max_xsec;
 }

void QELEventGeneratorSuSA::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 582 of file QELEventGeneratorSuSA.cxx.

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

void QELEventGeneratorSuSA::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 588 of file QELEventGeneratorSuSA.cxx.

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

void QELEventGeneratorSuSA::GenerateNucleon ( GHepRecord * event ) const

private

Definition at line 356 of file QELEventGeneratorSuSA.cxx.

 {
     // We need a kinematic limits accept/reject loop here, so generating the
     // initial hadrons is combined with generating the recoil hadrons...
 
     LOG("QELEvent",pDEBUG) << "Generate Nucleon - Start";
 
     Interaction * interaction = event->Summary();
     GHepParticle * neutrino = event->Probe();
     assert(neutrino);
     TLorentzVector p4nu(*neutrino->P4());
 
     // get final state primary lepton & its 4-momentum
     GHepParticle * fsl = event->FinalStatePrimaryLepton();
     assert(fsl);
     TLorentzVector p4l(*fsl->P4());
 
     // calculate 4-momentum transfer from these
     TLorentzVector Q4 = p4nu - p4l;
     //Q4.Print();
 
     // get the target nucleon and nucleus.
     // the remnant nucleus is apparently set, except for its momentum.
     GHepParticle * target_nucleus = event->TargetNucleus();
     bool have_nucleus = (target_nucleus != 0);
     //assert(target_nucleus);
     GHepParticle * initial_nucleon = event->HitNucleon();
     assert(initial_nucleon);
     GHepParticle * remnant_nucleus = event->RemnantNucleus();
     //assert(remnant_nucleus);
 
     // instantiate an empty local target nucleus, so I can use existing methods
     // to get a momentum from the prevailing Fermi-motion distribution
     int tgtpdg;
     if(have_nucleus) tgtpdg = target_nucleus->Pdg();
     else tgtpdg = kPdgTgtFreeP;
     Target tgt(tgtpdg);
 
     // These things need to be saved through to the end of the accept loop.
     bool accept = false;
     TVector3 p3i;
     unsigned int iter = 0;
 
     int initial_nucleon_pdg = initial_nucleon->Pdg();
     int final_nucleon_pdg = interaction->RecoilNucleonPdg();
 
     TLorentzVector p4initial_nucleon;
     TLorentzVector p4final_nucleon;
     double removalenergy;
 
     //remnant kinematic alterations
     double pxb = 0;
     double pyb = 0;
     double pzb = 0;
 
     //===========================================================================
     // Choose nucleons from the prevailing fermi-motion distribution.
     // Possible to produce kinematically unallowed (Pauli blocked) nucleon.
     // Find out, and if so choose them again with this accept/reject loop.
     // Pauli blocking was included in the SuSAv2 tensor tables, so it should not
     // be allowed to affect the inclusive xsec.
     while(!accept){
         iter++;
         if(iter > kRjMaxIterations) {
             // error if try too many times
             LOG("QELEvent", pWARN)
                 << "Couldn't select a valid nucleon after "
                 << iter << " iterations";
             event->EventFlags()->SetBitNumber(kKineGenErr, true);
             genie::exceptions::EVGThreadException exception;
             exception.SetReason("Couldn't select initial hadron kinematics");
             exception.SwitchOnFastForward();
             throw exception;
         }
 
         // generate nucleons
         // tgt is a Target object for local use, just waiting to be filled.
         // this sets the pdg of each nucleon and its momentum from user chosen nuclear model
 
         double hitNucPos = initial_nucleon->X4()->Vect().Mag();
         tgt.SetHitNucPdg(initial_nucleon_pdg);
         fNuclModel->GenerateNucleon(tgt,hitNucPos);
         p3i = fNuclModel->Momentum3();
 
         // Default: Calculate the removal energy as in Guille's thesis - this is a simplicification of
         // a fairly complex aproach employed in SuSAv2, but we expect it to work pretty well.
         // We should write something about this in the implementation technical paper ...
         // IMPORTANT CAVEAT: By default we choose to allow the binding energy to depend on the interaction
         // (as it should), but this means we don't corrolate the chosen Eb with the intial nucleon
         // momentum. Therefore we can sometimes have initial state nucleons with KE>Eb. This isn't
         // great, but fot the moment it's what we have (working on improvments).
 
         double q3 = Q4.Vect().Mag();
 
         if(!have_nucleus){
           // For elastic case no Fermi momentum and no Eb
           removalenergy = 0.0;
           p3i.SetXYZ(0.0,0.0,0.0);
         }
         else if(fForceEbFromModel) removalenergy = fNuclModel->RemovalEnergy();
         else if(fForceFixEb) removalenergy = fEbOR;
         else{
           if(q3<0.827){
             removalenergy = -0.017687 + 0.0564*q3;
           }
           else{
             removalenergy = 0.0289558;
           }
           // The above is for Carbon, should shift for different targets
           removalenergy += (fNuclModel->RemovalEnergy()) - fEbC;
           if(removalenergy<0.005) removalenergy=0.005;
         }
 
         //removalenergy=0.0;
         //initial_nucleon->SetRemovalEnergy(removalenergy);
 
         LOG("QELEvent",pDEBUG) << "q3 for this event:" << q3;
         LOG("QELEvent",pDEBUG) << "Removal energy:" << removalenergy;
 
         // Now write down the initial nucleon four-vector for this choice
         double mass = PDGLibrary::Instance()->Find( initial_nucleon_pdg )->Mass();
         double mass2 = mass*mass;
         double energy = TMath::Sqrt(p3i.Mag2() + mass2);
         p4initial_nucleon.SetPxPyPzE(p3i.Px(),p3i.Py(),p3i.Pz(),energy);
 
         //One rather unsubtle option for making sure nucleons remain bound.
         //This will give us bound nucleons with a sensible missing eneergy
         //but the distribution of Fermi motion will look crazy.
         // Anything we do is wrong (without semi-inclusive inputs) you just
         // have to decide what is less wrong!
         if(fForceBound && (energy-mass>removalenergy)) continue;
 
         // cast the removal energy as the energy component of a 4-vector for later.
         TLorentzVector tLVebind(0., 0., 0., -1.0 * (removalenergy));
 
         // Taken from MEC event generator:
         // calculate recoil nucleon cluster 4-momentum (tLVebind is negative)
         p4final_nucleon = p4initial_nucleon + Q4 + tLVebind;
 
         // Put on shell as in the Aggregator
         // This is a bit of a horrible approximation but it is hard to think
         // of anything simple and better without semi-inclusive model predictions.
         // However, we are working on an improvments.
         if(have_nucleus){
           double En = p4final_nucleon.E();
           double M = PDGLibrary::Instance()->Find( final_nucleon_pdg )->Mass();
           double pmag_old = p4final_nucleon.Vect().Mag();
 
           double pmag_new = TMath::Sqrt(utils::math::NonNegative(En*En-M*M));
           double scale    = pmag_new / pmag_old;
 
           double pxn = scale * p4final_nucleon.Px();
           double pyn = scale * p4final_nucleon.Py();
           double pzn = scale * p4final_nucleon.Pz();
 
           p4final_nucleon.SetPxPyPzE(pxn,pyn,pzn,En);
         }
 
         // Extra momentum xfer to keep nucleon on shell - I'll give this to the remnant
 
         pxb = p4nu.Px()-p4l.Px()-p4final_nucleon.Px();
         pyb = p4nu.Py()-p4l.Py()-p4final_nucleon.Py();
         pzb = p4nu.Pz()-p4l.Pz()-p4final_nucleon.Pz();
 
         LOG("QELEvent",pDEBUG) << "Remnant momentum is: (" << pxb << ", " << pyb << ", " << pzb << ")";
 
 
         // Pauli blocking check:
         // Test if the resulting four-vector corresponds to a high-enough energy.
         // Fail the accept if we couldn't put this thing on-shell.
         // Basically: is energy of the nucleon positive after we subtracting Eb
         if (p4final_nucleon.E() < PDGLibrary::Instance()->Find(final_nucleon_pdg)->Mass()) {
             accept = false;
             LOG("QELEvent",pDEBUG) << "Rejected nucleon, can't be put on-shell";
             LOG("QELEvent",pDEBUG) << "Nucleon invariant mass:" << p4final_nucleon.M();
             LOG("QELEvent",pDEBUG) << "Nucleon real mass:" << PDGLibrary::Instance()->Find(final_nucleon_pdg)->Mass();
             LOG("QELEvent",pDEBUG) << "Nucleon 4 momenutum:";
             //p4final_nucleon.Print();
             LOG("QELEvent",pDEBUG) << "Removal energy:" << removalenergy;
             LOG("QELEvent",pDEBUG) << "Q4 transfer:";
             //Q4.Print();
         }
         else {
             accept = true;
             LOG("QELEvent",pDEBUG) << "Nucleon accepted, Q4 is";
             //Q4.Print();
             LOG("QELEvent",pDEBUG) << "Initial nucleon mass is" << sqrt((p4initial_nucleon.E()*p4initial_nucleon.E())-(p4initial_nucleon.Vect().Mag()*p4initial_nucleon.Vect().Mag()));
             LOG("QELEvent",pDEBUG) << "Final nucleon mass is" << sqrt((p4final_nucleon.E()*p4final_nucleon.E())-(p4final_nucleon.Vect().Mag()*p4final_nucleon.Vect().Mag()));
             LOG("QELEvent",pDEBUG) << "Nucleon invariant mass:" << p4final_nucleon.M();
             LOG("QELEvent",pDEBUG) << "Nucleon real mass:" << PDGLibrary::Instance()->Find(final_nucleon_pdg)->Mass();
             LOG("QELEvent",pDEBUG) << "Nucleon 4 momenutum:";
             //p4final_nucleon.Print();
             LOG("QELEvent",pDEBUG) << "Removal energy:" << removalenergy;
             LOG("QELEvent",pDEBUG) << "Q4 transfer:";
         }
 
     }  // end accept loop
 
     // we got here if we accepted the final state hadron system
     // so now we need to write everything to ghep
 
     // First the initial state nucleon.
     initial_nucleon->SetMomentum(p4initial_nucleon);
 
     // and the remnant nucleus
     if(have_nucleus){
       double Mi  = PDGLibrary::Instance()->Find(target_nucleus->Pdg() )-> Mass();
       remnant_nucleus->SetMomentum(pxb,pyb,pzb, Mi - p4initial_nucleon.E() + removalenergy);
     }
 
     // Getting this v4 is a position, i.e. a position within the nucleus (?)
     // possibly it takes on a non-trivial value only for local Fermi gas
     // or for sophisticated treatments of intranuclear rescattering.
     TLorentzVector v4(*neutrino->X4());
 
     // Now add the final nucleon
 
     interaction->KinePtr()->SetHadSystP4(p4final_nucleon);
 
     GHepStatus_t ist = (tgt.IsNucleus()) ? kIStHadronInTheNucleus : kIStStableFinalState;
     event->AddParticle(interaction->RecoilNucleonPdg(), ist, event->HitNucleonPosition(),-1,-1,-1, interaction->KinePtr()->HadSystP4(), v4);
 
     LOG("QELEvent",pDEBUG) << "Generate Nucleon - End";
 
 }

void QELEventGeneratorSuSA::LoadConfig ( void )

private

Definition at line 594 of file QELEventGeneratorSuSA.cxx.

 {
     fNuclModel = 0;
     RgKey nuclkey = "NuclearModel";
     fNuclModel = dynamic_cast<const NuclearModelI *> ( this->SubAlg(nuclkey) );
     assert( fNuclModel );
 
     // Sub-algorithm for generating events on free nucleon targets
     // (not handled by the SuSAv2 calculation)
     fFreeNucleonEventGenerator = dynamic_cast<const EventRecordVisitorI* >(
       this->SubAlg("FreeNucleonEventGenerator") );
     assert( fFreeNucleonEventGenerator );
 
     //-- Maximum q3 in input hadron tensors
     GetParam( "QEL-Q3Max", fQ3Max ) ;
 
     //-- Whether to force nucleons to be bound
     GetParam( "QEL-ForceBound", fForceBound) ;
 
     //-- Whether to force Eb to come from the nuclear model
     GetParam( "QEL-ForceEbFromModel", fForceEbFromModel) ;
 
     //-- Whether to force some fixed Eb
     GetParam( "QEL-ForceFixedEb", fForceFixEb) ;
     GetParam( "QEL-EbOR", fEbOR) ;
 
     //-- Carbon Eb - needed for scaling
     this->GetParam( "RFG-NucRemovalE@Pdg=1000060120", fEbC);
 
     //-- Safety factor for the maximum differential cross section
     GetParamDef( "MaxXSec-SafetyFactor", fSafetyFactor , 5.00 ) ;
 
     //-- Minimum energy for which max xsec would be cached, forcing explicit
     //   calculation for lower energies
     //-- I've set this to an extremely high value to avoid problems with the
     //   SuSAv2 model seen during testing. Everything seems to work OK when
     //   the cache is disabled. - S. Gardiner, 1 July 2020
     GetParamDef( "Cache-MinEnergy", fEMin, 1000.00 ) ;
 
     //-- 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? NOT IMPLEMENTED FOR SUSA YET!
     GetParamDef( "UniformOverPhaseSpace", fGenerateUniformly, false ) ;
 }

void QELEventGeneratorSuSA::ProcessEventRecord ( GHepRecord * event ) const

virtual

Implements genie::EventRecordVisitorI.

Definition at line 68 of file QELEventGeneratorSuSA.cxx.

 {
   // If we're working with a free nucleon target, then the SuSAv2 calculation
   // isn't set up to handle it. In these cases, we delegate the work to another
   // EventRecordVisitorI object (likely QELEventGenerator) configured to run as
   // a sub-algorithm.
   if ( !event->Summary()->InitState().Tgt().IsNucleus() ) {
     return fFreeNucleonEventGenerator->ProcessEventRecord( event );
   }
 
   //-- Access cross section algorithm for running thread
   RunningThreadInfo * rtinfo = RunningThreadInfo::Instance();
   const EventGeneratorI * evg = rtinfo->RunningThread();
   fXSecModel = evg->CrossSectionAlg();
   //event->Print();
   this -> SelectLeptonKinematics(event);
   //event->Print();
   this -> AddTargetNucleusRemnant(event);
   //event->Print();
   this -> GenerateNucleon(event);
   //event->Print();
 }

void QELEventGeneratorSuSA::SelectLeptonKinematics ( GHepRecord * event ) const

private

Definition at line 91 of file QELEventGeneratorSuSA.cxx.

 {
 
   // -- Event Properties -----------------------------//
   Interaction * interaction = event->Summary();
   Kinematics * kinematics = interaction->KinePtr();
 
   // Choose the appropriate minimum Q^2 value based on the interaction
   // mode (this is important for EM interactions since the differential
   // cross section blows up as Q^2 --> 0)
   double Q2min = genie::controls::kMinQ2Limit; // CC/NC limit
   if ( interaction->ProcInfo().IsEM() ) Q2min = genie::utils::kinematics
     ::electromagnetic::kMinQ2Limit; // EM limit
 
   // The SuSA 1p1h model kinematics works in a system where
   // the whole nuclear target system has no momentum.
   double Enu = interaction->InitState().ProbeE(kRfLab);
 
   int NuPDG = interaction->InitState().ProbePdg();
   int TgtPDG = interaction->InitState().TgtPdg();
   // interacton vtx
   TLorentzVector v4(*event->Probe()->X4());
   TLorentzVector tempp4(0.,0.,0.,0.);
 
   GHepParticle * nucleus = event->TargetNucleus();
   bool have_nucleus = nucleus != 0;
 
   // -- Lepton Kinematic Limits ----------------------------------------- //
   double Costh = 0.0; // lepton angle
   double CosthMax = 1.0;
   double CosthMin = -1.0;
 
   double T = 0.0;  // lepton kinetic energy
   double TMax = std::numeric_limits<double>::max();
   double TMin = 0.0;
 
   double Plep = 0.0; // lepton 3 momentum
   double Elep = 0.0; // lepton energy
   double LepMass = interaction->FSPrimLepton()->Mass();
 
   double Q0 = 0.0; // energy component of q four vector
   double Q3 = 0.0; // magnitude of transfered 3 momentum
   double Q2 = 0.0; // properly Q^2 (Q squared) - transfered 4 momentum.
 
   // Set lepton KE TMax for for throwing rndm in the accept/reject loop.
   // We can accidentally set it too high, because the xsec will return zero.
   // This way if someone reuses this code, they are not tripped up by it.
   TMax = Enu - LepMass;
 
   // Set Tmin for throwing rndm in the accept/reject loop
   // the hadron tensors we expect will be limited in q3
   // therefore also the outgoing lepton KE can't be too low or costheta too backward
   // make the accept/reject loop more efficient by using Min values.
   if(Enu < fQ3Max){
     TMin = 0 ;
     CosthMin = -1 ;
   } else {
     TMin = TMath::Sqrt(TMath::Power(LepMass, 2) + TMath::Power((Enu - fQ3Max), 2)) - LepMass;
     CosthMin = TMath::Sqrt(1 - TMath::Power((fQ3Max / Enu ), 2));
   }
 
 
   // -- Generate and Test the Kinematics----------------------------------//
 
   RandomGen * rnd = RandomGen::Instance();
   bool accept = false;
   unsigned int iter = 0;
   unsigned int maxIter = kRjMaxIterations * 1000;
 
   //e-scat xsecs blow up close to theta=0, MC methods won't work so well...
   // NOTE: SuSAv2 1p1h e-scatting has not been validated yet, use with caution
   if ( NuPDG == 11 ) maxIter *= 1000;
 
   // Get Max XSec:
   double XSecMax = this->MaxXSec( event );
 
   LOG("Kinematics", pDEBUG) << "Max XSec = " << XSecMax;
 
   // loop over different (randomly) selected T and Costh
   while (!accept) {
       iter++;
       if(iter > maxIter) {
           // error if try too many times
           LOG("QELEvent", pERROR)
               << "Couldn't select a valid Tmu, CosTheta pair after "
               << iter << " iterations";
           event->EventFlags()->SetBitNumber(kKineGenErr, true);
           genie::exceptions::EVGThreadException exception;
           exception.SetReason("Couldn't select lepton kinematics");
           exception.SwitchOnFastForward();
           throw exception;
       }
 
       // generate random kinetic energy T and Costh
       T = TMin + (TMax-TMin)*rnd->RndKine().Rndm();
       Costh = CosthMin + (CosthMax-CosthMin)*rnd->RndKine().Rndm();
 
       // Calculate useful values for judging this choice
       Plep = TMath::Sqrt( T * (T + (2.0 * LepMass)));  // ok is sqrt(E2 - m2)
       Q3 = TMath::Sqrt(Plep*Plep + Enu*Enu - 2.0 * Plep * Enu * Costh);
 
       // Calculate what we need to enforce the minimum Q^2 cut
       Q0 = Enu - (T + LepMass);
       Q2 = Q3*Q3 - Q0*Q0;
 
       // Anti neutrino elastic scattering case - include delta in xsec
       if (!have_nucleus){
         genie::utils::mec::Getq0q3FromTlCostl(T, Costh, Enu, LepMass, Q0, Q3);
         Q3 = sqrt(Q0*Q0+2*kNucleonMass*Q0);
         genie::utils::mec::GetTlCostlFromq0q3(Q0, Q3, Enu, LepMass, T, Costh);
         LOG("QELEvent", pDEBUG) << " Anu elastic case. T, Costh:  " << T << ", " << Costh ;
         LOG("QELEvent", pDEBUG) << " Anu elastic case. Q0, Q3:  " << Q0 << ", " << Q3 ;
       }
 
       // Don't bother doing hard work if the selected Q3 is greater than Q3Max
       // or if Q^2 is less than the minimum allowed value
       if ( Q3 < fQ3Max && Q2 >= Q2min ){
 
           kinematics->SetKV(kKVTl, T);
           kinematics->SetKV(kKVctl, Costh);
           LOG("QELEvent", pDEBUG) << " T, Costh, Q2: " << T << ", " << Costh << ", " << Q2;
 
           double XSec = fXSecModel->XSec(interaction, kPSTlctl);
 
           // Some debugging if things go wrong here...
           if (XSec > XSecMax) {
               LOG("QELEvent", pDEBUG) << "XSec in cm2 is  " << XSec/(units::cm2);
               LOG("QELEvent", pDEBUG) << "XSec in cm2 /neutron is  " << XSec/(units::cm2*pdg::IonPdgCodeToZ(TgtPDG));
               LOG("QELEvent", pDEBUG) << "XSecMax in cm2 /neutron is  " << XSecMax/(units::cm2*pdg::IonPdgCodeToZ(TgtPDG));
               LOG("QELEvent", pERROR) << " T, Costh, Q2: " << T << ", " << Costh << ", " << Q2;
               LOG("QELEvent", pERROR) << "XSec is > XSecMax for nucleus " << TgtPDG << " "
                                  << XSec << " > " << XSecMax
                                  << " don't let this happen.";
           }
           // decide whether to accept or reject these kinematics
           this->AssertXSecLimits( interaction, XSec, XSecMax );
           accept = XSec > XSecMax*rnd->RndKine().Rndm();
           LOG("QELEvent", pINFO) << "Xsec, Max, Accept: " << XSec << ", "
               << XSecMax << ", " << accept;
               LOG("QELEvent", pDEBUG) << "XSec in cm2 /neutron is  " << XSec/(units::cm2*pdg::IonPdgCodeToZ(TgtPDG));
               LOG("QELEvent", pDEBUG) << "XSecMax in cm2 /neutron is  " << XSecMax/(units::cm2*pdg::IonPdgCodeToZ(TgtPDG));
 
 
       }// end if passes q3 test
   } // end main accept-reject loop
 
   // -- finish lepton kinematics
   // If the code got here, then we accepted some kinematics
   // and we can proceed to generate the final state.
 
   // define coordinate system wrt neutrino: z along neutrino, xy perp
 
   // Cos theta gives us z, the rest in xy:
   double PlepZ = Plep * Costh;
   double PlepXY = Plep * TMath::Sqrt(1. - TMath::Power(Costh,2));
 
   // random rotation about unit vector for phi direction
   double phi= 2 * kPi * rnd->RndLep().Rndm();
   // now fill x and y from PlepXY
   double PlepX = PlepXY * TMath::Cos(phi);
   double PlepY = PlepXY * TMath::Sin(phi);
 
   // Rotate lepton momentum vector from the reference frame (x'y'z') where
   // {z':(neutrino direction), z'x':(theta plane)} to the LAB
   TVector3 unit_nudir = event->Probe()->P4()->Vect().Unit();
   TVector3 p3l(PlepX, PlepY, PlepZ);
   p3l.RotateUz(unit_nudir);
 
   // Lepton 4-momentum in LAB
   Elep = TMath::Sqrt(LepMass*LepMass + PlepX*PlepX + PlepY*PlepY + PlepZ*PlepZ);
   TLorentzVector p4l(p3l,Elep);
 
   // Figure out the final-state primary lepton PDG code
   int pdgc = interaction->FSPrimLepton()->PdgCode();
   int momidx = event->ProbePosition();
 
   // -- Store Values ------------------------------------------//
   // -- Interaction: Q2
   Q0 = Enu - Elep;
   Q2 = Q3*Q3 - Q0*Q0;
   double gy = Q0 / Enu;
   double gx = kinematics::Q2YtoX(Enu, 2 * kNucleonMass, Q2, gy);
   double gW = kinematics::XYtoW(Enu, 2 * kNucleonMass, gx, gy);
 
   interaction->KinePtr()->SetQ2(Q2, true);
   interaction->KinePtr()->Sety(gy, true);
   interaction->KinePtr()->Setx(gx, true);
   interaction->KinePtr()->SetW(gW, true);
   interaction->KinePtr()->SetFSLeptonP4(p4l);
 
   // -- Lepton
   event->AddParticle( pdgc, kIStStableFinalState, momidx, -1, -1, -1, p4l, v4);
 
   LOG("QELEvent",pDEBUG) << "~~~ LEPTON DONE ~~~";
 }

Member Data Documentation

double genie::QELEventGeneratorSuSA::fEbC

private

Definition at line 64 of file QELEventGeneratorSuSA.h.

double genie::QELEventGeneratorSuSA::fEbOR

private

Definition at line 61 of file QELEventGeneratorSuSA.h.

bool genie::QELEventGeneratorSuSA::fForceBound

private

Definition at line 58 of file QELEventGeneratorSuSA.h.

bool genie::QELEventGeneratorSuSA::fForceEbFromModel

private

Definition at line 59 of file QELEventGeneratorSuSA.h.

bool genie::QELEventGeneratorSuSA::fForceFixEb

private

Definition at line 60 of file QELEventGeneratorSuSA.h.

const EventRecordVisitorI* genie::QELEventGeneratorSuSA::fFreeNucleonEventGenerator

private

Delegate event generation for free nucleon targets (which are not handled by the SuSAv2 calculation) to a different event generator

Definition at line 69 of file QELEventGeneratorSuSA.h.

const NuclearModelI* genie::QELEventGeneratorSuSA::fNuclModel

private

Definition at line 55 of file QELEventGeneratorSuSA.h.

double genie::QELEventGeneratorSuSA::fQ3Max

private

Definition at line 57 of file QELEventGeneratorSuSA.h.

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

Generator/src/Physics/QuasiElastic/EventGen/QELEventGeneratorSuSA.h
Generator/src/Physics/QuasiElastic/EventGen/QELEventGeneratorSuSA.cxx

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation