genie::NewQELXSec Class Reference

Computes the Quasi Elastic (QEL) total cross section.
Is a concrete implementation of the XSecIntegratorI interface.
. More...

#include <NewQELXSec.h>

Inheritance diagram for genie::NewQELXSec:

Collaboration diagram for genie::NewQELXSec:

Public Member Functions
	NewQELXSec (void)
	NewQELXSec (std::string config)
double	Integrate (const XSecAlgorithmI *model, const Interaction *i) const
	XSecIntegratorI interface implementation.
void	Configure (const Registry &config)
void	Configure (std::string config)
Public Member Functions inherited from genie::XSecIntegratorI
virtual	~XSecIntegratorI ()
Public Member Functions inherited from genie::Algorithm
virtual	~Algorithm ()
virtual void	Configure (string config)
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)

Private Attributes
std::string	fGSLIntgType
double	fGSLRelTol
unsigned int	fGSLMaxEval
AlgId	fVertexGenID
int	fNumNucleonThrows
double	fMinAngleEM
bool	fAverageOverNucleons

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::XSecIntegratorI
	XSecIntegratorI ()
	XSecIntegratorI (string name)
	XSecIntegratorI (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::XSecIntegratorI
const IntegratorI *	fIntegrator
	GENIE numerical integrator.
string	fGSLIntgType
	name of GSL numerical integrator
double	fGSLRelTol
	required relative tolerance (error)
int	fGSLMaxEval
	GSL max evaluations.
int	fGSLMinEval
	GSL min evaluations. Ignored by some integrators.
unsigned int	fGSLMaxSizeOfSubintervals
	GSL maximum number of sub-intervals for 1D integrator.
unsigned int	fGSLRule
	GSL Gauss-Kronrod integration rule (only for GSL 1D adaptive type)
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

Computes the Quasi Elastic (QEL) total cross section.
Is a concrete implementation of the XSecIntegratorI interface.
.

Author

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

Created:\n February 26, 2019

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 63 of file NewQELXSec.h.

Constructor & Destructor Documentation

NewQELXSec() [1/2]

NewQELXSec::NewQELXSec

(

void

)

Definition at line 39 of file NewQELXSec.cxx.

                       : XSecIntegratorI("genie::NewQELXSec")
{
 
}

References genie::XSecIntegratorI::XSecIntegratorI().

NewQELXSec() [2/2]

NewQELXSec::NewQELXSec

(

std::string

config

)

Definition at line 44 of file NewQELXSec.cxx.

                                       : XSecIntegratorI("genie::NewQELXSec", config)
{
 
}

References genie::XSecIntegratorI::XSecIntegratorI().

Member Function Documentation

Configure() [1/2]

void NewQELXSec::Configure ( const Registry & config )

virtual

Overload the Algorithm::Configure() methods to load private data members from configuration options

Reimplemented from genie::Algorithm.

Definition at line 172 of file NewQELXSec.cxx.

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

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

Configure() [2/2]

void genie::NewQELXSec::Configure

(

std::string

config

)

Integrate()

double NewQELXSec::Integrate ( const XSecAlgorithmI * model, const Interaction * i ) const

virtual

XSecIntegratorI interface implementation.

Implements genie::XSecIntegratorI.

Definition at line 49 of file NewQELXSec.cxx.

{
  LOG("NewQELXSec",pDEBUG) << "Beginning integrate";
  if ( !model->ValidProcess(in) ) return 0.;
 
  Interaction* interaction = new Interaction( *in );
  interaction->SetBit( kISkipProcessChk );
  //interaction->SetBit( kISkipKinematicChk );
 
  const NuclearModelI* nucl_model = dynamic_cast<const NuclearModelI*>(
    model->SubAlg("IntegralNuclearModel") );
  assert( nucl_model );
 
  AlgFactory* algf = AlgFactory::Instance();
  const VertexGenerator* vtx_gen = dynamic_cast<const VertexGenerator*>(
    algf->GetAlgorithm(fVertexGenID) );
  assert( vtx_gen );
 
  // Determine the appropriate binding energy mode to use.
  // The default given here is for the case of a free nucleon.
  QELEvGen_BindingMode_t bind_mode = kOnShell;
  Target* tgt = interaction->InitState().TgtPtr();
  if ( tgt->IsNucleus() ) {
    std::string bind_mode_str = model->GetConfig()
      .GetString( "IntegralNucleonBindingMode" );
    bind_mode = genie::utils::StringToQELBindingMode( bind_mode_str );
  }
 
  utils::gsl::FullQELdXSec* func = new utils::gsl::FullQELdXSec(model,
    interaction, bind_mode, fMinAngleEM);
  ROOT::Math::IntegrationMultiDim::Type ig_type =
    utils::gsl::IntegrationNDimTypeFromString( fGSLIntgType );
 
  // Switch to using the copy of the interaction in the integrator rather than
  // the copy that we made in this function
  delete interaction;
  interaction = func->GetInteractionPtr();
 
  // Also update the pointer to the Target
  tgt = interaction->InitState().TgtPtr();
 
  double abstol = 1e-16; // We mostly care about relative tolerance
  ROOT::Math::IntegratorMultiDim ig(*func, ig_type, abstol, fGSLRelTol, fGSLMaxEval);
 
  // Integration ranges for the lepton COM frame scattering angles (in the
  // kPSQELEvGen phase space, these are measured with respect to the COM
  // velocity as observed in the lab frame)
  Range1D_t cos_theta_0_lim( -1., 1. );
  Range1D_t phi_0_lim( 0., 2.*kPi );
 
  double kine_min[2] = { cos_theta_0_lim.min, phi_0_lim.min };
  double kine_max[2] = { cos_theta_0_lim.max, phi_0_lim.max };
 
  // If averaging over the initial nucleon distribution has been
  // disabled, just integrate over angles and return the result.
  if ( !fAverageOverNucleons ) {
    double xsec_total = ig.Integral(kine_min, kine_max);
    delete func;
    return xsec_total;
  }
 
  // For a free nucleon target (hit nucleon is at rest in the lab frame), we
  // don't need to do an MC integration over the initial state variables. In
  // this case, just set up the nucleon at the origin, on-shell, and at rest,
  // then integrate over the angles and return the result.
 
  // Also use this approach if we're over the "nuclear influence" cutoff
  // energy for the probe. Beyond the cutoff, the effects of Fermi motion
  // and the removal energy are assumed to be small enough to be neglected
  double E_lab_cutoff = model->GetConfig()
    .GetDouble("IntegralNuclearInfluenceCutoffEnergy");
 
  double probeE = interaction->InitState().ProbeE( kRfLab );
  if ( !tgt->IsNucleus() || probeE > E_lab_cutoff ) {
    tgt->SetHitNucPosition(0.);
 
    if ( tgt->IsNucleus() ) nucl_model->GenerateNucleon(*tgt, 0.);
    else {
      nucl_model->SetRemovalEnergy(0.);
      interaction->SetBit( kIAssumeFreeNucleon );
    }
 
    nucl_model->SetMomentum3( TVector3(0., 0., 0.) );
    double xsec_total = ig.Integral(kine_min, kine_max);
    delete func;
    return xsec_total;
  }
 
  // For a nuclear target, we need to loop over a bunch of nucleons sampled
  // from the nuclear model (with positions sampled from the vertex generator
  // to allow for using the local Fermi gas model). The MC estimator for the
  // total cross section is simply the mean of ig.Integral() for all of the
  // sampled nucleons.
  double xsec_sum = 0.;
  for (int n = 0; n < fNumNucleonThrows; ++n) {
 
    // Select a new position for the initial hit nucleon (needed for the local
    // Fermi gas model, but other than slowing things down a bit, it doesn't
    // hurt to do this for other models)
    TVector3 vertex_pos = vtx_gen->GenerateVertex( interaction, tgt->A() );
    double radius = vertex_pos.Mag();
    tgt->SetHitNucPosition( radius );
 
    // Sample a new nucleon 3-momentum and removal energy (this will be applied
    // to the nucleon via a call to genie::utils::ComputeFullQELPXSec(), so
    // there's no need to mess with its 4-momentum here)
    nucl_model->GenerateNucleon(*tgt, radius);
 
    // The initial state variables have all been defined, so integrate over
    // the final lepton angles.
    double xsec = ig.Integral(kine_min, kine_max);
 
    xsec_sum += xsec;
  }
 
  delete func;
 
  // MC estimator of the total cross section is the mean of the xsec values
  double xsec_mean = xsec_sum / fNumNucleonThrows;
 
  return xsec_mean;
}

References genie::Target::A(), e, fAverageOverNucleons, fGSLIntgType, fGSLMaxEval, fGSLRelTol, fMinAngleEM, fNumNucleonThrows, func(), fVertexGenID, genie::NuclearModelI::GenerateNucleon(), genie::VertexGenerator::GenerateVertex(), genie::AlgFactory::GetAlgorithm(), genie::Algorithm::GetConfig(), genie::Registry::GetDouble(), genie::Registry::GetString(), genie::Interaction::InitState(), genie::AlgFactory::Instance(), genie::utils::gsl::IntegrationNDimTypeFromString(), genie::Target::IsNucleus(), genie::kIAssumeFreeNucleon, genie::kISkipProcessChk, genie::kOnShell, genie::constants::kPi, genie::kRfLab, LOG, genie::Range1D_t::max, genie::Range1D_t::min, pDEBUG, genie::InitialState::ProbeE(), genie::Target::SetHitNucPosition(), genie::NuclearModelI::SetMomentum3(), genie::NuclearModelI::SetRemovalEnergy(), genie::utils::StringToQELBindingMode(), genie::Algorithm::SubAlg(), genie::InitialState::TgtPtr(), and genie::XSecAlgorithmI::ValidProcess().

LoadConfig()

void NewQELXSec::LoadConfig ( void )

private

Definition at line 184 of file NewQELXSec.cxx.

{
  // Get GSL integration type & relative tolerance
  GetParamDef( "gsl-integration-type", fGSLIntgType, std::string("adaptive") ) ;
  GetParamDef( "gsl-relative-tolerance", fGSLRelTol, 1e-2 ) ;
  int max;
  GetParamDef( "gsl-max-eval", max, 500000 ) ;
  fGSLMaxEval  = static_cast<unsigned int>( max );
 
  RgAlg vertexGenID;
  GetParamDef( "VertexGenAlg", vertexGenID, RgAlg("genie::VertexGenerator", "Default") );
  fVertexGenID = AlgId( vertexGenID );
 
  GetParamDef( "NumNucleonThrows", fNumNucleonThrows, 5000 );
 
  // TODO: This is a parameter that may also be specified in the XML
  // configuration for QELEventGenerator. Avoid duplication here to ensure
  // consistency.
  GetParamDef( "SF-MinAngleEMscattering", fMinAngleEM, 0. ) ;
 
  // If true, then the integration of the total cross section will include an
  // MC integration over the initial state nuclear model
  GetParamDef( "AverageOverNucleons", fAverageOverNucleons, true );
}

References e, fAverageOverNucleons, fGSLIntgType, fGSLMaxEval, fGSLRelTol, fMinAngleEM, fNumNucleonThrows, fVertexGenID, and genie::Algorithm::GetParamDef().

Referenced by Configure().

Member Data Documentation

fAverageOverNucleons

bool genie::NewQELXSec::fAverageOverNucleons

private

Definition at line 100 of file NewQELXSec.h.

Referenced by Integrate(), and LoadConfig().

fGSLIntgType

std::string genie::NewQELXSec::fGSLIntgType

private

Definition at line 86 of file NewQELXSec.h.

Referenced by Integrate(), and LoadConfig().

fGSLMaxEval

unsigned int genie::NewQELXSec::fGSLMaxEval

private

Definition at line 88 of file NewQELXSec.h.

Referenced by Integrate(), and LoadConfig().

fGSLRelTol

double genie::NewQELXSec::fGSLRelTol

private

Definition at line 87 of file NewQELXSec.h.

Referenced by Integrate(), and LoadConfig().

fMinAngleEM

double genie::NewQELXSec::fMinAngleEM

private

Definition at line 91 of file NewQELXSec.h.

Referenced by Integrate(), and LoadConfig().

fNumNucleonThrows

int genie::NewQELXSec::fNumNucleonThrows

private

Definition at line 90 of file NewQELXSec.h.

Referenced by Integrate(), and LoadConfig().

fVertexGenID

AlgId genie::NewQELXSec::fVertexGenID

private

Definition at line 89 of file NewQELXSec.h.

Referenced by Integrate(), and LoadConfig().

---

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

• NewQELXSec.h
• NewQELXSec.cxx