genie::DISXSec Class Reference

Computes the DIS Cross Section.
Is a concrete implementation of the XSecIntegratorI interface.
. More...

#include <DISXSec.h>

Inheritance diagram for genie::DISXSec:

Collaboration diagram for genie::DISXSec:

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

Private Attributes
double	fVldEmin
double	fVldEmax

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 DIS Cross Section.
Is a concrete implementation of the XSecIntegratorI interface.
.

Author

Costas Andreopoulos <c.andreopoulos \at cern.ch> University of Liverpool

Created:\n May 04, 2004

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 26 of file DISXSec.h.

Constructor & Destructor Documentation

DISXSec() [1/2]

DISXSec::DISXSec

(

)

Definition at line 39 of file DISXSec.cxx.

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

References genie::XSecIntegratorI::XSecIntegratorI().

DISXSec() [2/2]

DISXSec::DISXSec

(

string

config

)

Definition at line 45 of file DISXSec.cxx.

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

References genie::XSecIntegratorI::XSecIntegratorI().

~DISXSec()

DISXSec::~DISXSec ( )

virtual

Definition at line 51 of file DISXSec.cxx.

{
 
}

Member Function Documentation

CacheBranchName()

string DISXSec::CacheBranchName ( const XSecAlgorithmI * model, const Interaction * in ) const

private

Definition at line 316 of file DISXSec.cxx.

{
// Build a unique name for the cache branch
 
  Cache * cache = Cache::Instance();
 
  string algkey = model->Id().Key();
  string ikey   = interaction->AsString();
  string key    = cache->CacheBranchKey(algkey, ikey);
  return key;
}

References genie::Interaction::AsString(), genie::Cache::CacheBranchKey(), genie::Algorithm::Id(), genie::Cache::Instance(), and genie::AlgId::Key().

Referenced by CacheFreeNucleonXSec(), and Integrate().

CacheFreeNucleonXSec()

void DISXSec::CacheFreeNucleonXSec ( const XSecAlgorithmI * model, const Interaction * in ) const

private

Definition at line 212 of file DISXSec.cxx.

{
  LOG("DISXSec", pWARN)
      << "Wait while computing/caching free nucleon DIS xsections first...";
 
  // Create the cache branch
  Cache * cache = Cache::Instance();
  string key = this->CacheBranchName(model,interaction);
  CacheBranchFx * cache_branch =
           dynamic_cast<CacheBranchFx *> (cache->FindCacheBranch(key));
  assert(!cache_branch);
  cache_branch = new CacheBranchFx("DIS XSec");
  cache->AddCacheBranch(key, cache_branch);
 
  // Tweak interaction to be on a free nucleon target
  Target * target = interaction->InitStatePtr()->TgtPtr();
  int nucpdgc = target->HitNucPdg();
  if(pdg::IsProton(nucpdgc)) { target->SetId(kPdgTgtFreeP); }
  else                       { target->SetId(kPdgTgtFreeN); }
 
  // Compute threshold
  const KPhaseSpace & kps = interaction->PhaseSpace();
  double Ethr = kps.Threshold();
 
  // Compute the number of spline knots - use at least 10 knots per decade
  // && at least 40 knots in the full energy range
  const double Emin       = fVldEmin/3.;
  const double Emax       = fVldEmax*3.;
  const int    nknots_min = (int) (10*(TMath::Log(Emax) - TMath::Log(Emin)));
  const int    nknots     = TMath::Max(40, nknots_min);
 
  // Distribute the knots in the energy range as is being done in the
  // XSecSplineList so that the energy threshold is treated correctly
  // in the spline - see comments there in.
  double * E = new double[nknots];
  int nkb = (Ethr>Emin) ? 5 : 0; // number of knots <  threshold
  int nka = nknots-nkb;          // number of knots >= threshold
  // knots < energy threshold
  double dEb =  (Ethr>Emin) ? (Ethr - Emin) / nkb : 0;
  for(int i=0; i<nkb; i++) {
      E[i] = Emin + i*dEb;
  }
  // knots >= energy threshold
  double E0  = TMath::Max(Ethr,Emin);
  double dEa = (TMath::Log10(Emax) - TMath::Log10(E0)) /(nka-1);
  for(int i=0; i<nka; i++) {
      E[i+nkb] = TMath::Power(10., TMath::Log10(E0) + i * dEa);
  }
 
  // Create the integrand
  ROOT::Math::IBaseFunctionMultiDim * func =
     new utils::gsl::d2XSec_dWdQ2_E(model, interaction);
 
  // Compute the cross section at the given set of knots
  for(int ie=0; ie<nknots; ie++) {
    double Ev = E[ie];
    TLorentzVector p4(0,0,Ev,Ev);
    interaction->InitStatePtr()->SetProbeP4(p4);
    double xsec = 0.;
    if(Ev>Ethr+kASmallNum) {
       Range1D_t Wl  = kps.WLim();
       Range1D_t Q2l = kps.Q2Lim();
       LOG("DISXSec", pINFO)
            << "W integration range = [" << Wl.min << ", " << Wl.max << "]";
       LOG("DISXSec", pINFO)
         << "Q2 integration range = [" << Q2l.min << ", " << Q2l.max << "]";
 
       bool phsp_ok =
          (Q2l.min >= 0. && Q2l.max >= 0. && Q2l.max >= Q2l.min &&
            Wl.min >= 0. &&  Wl.max >= 0. &&  Wl.max >=  Wl.min);
 
       if(phsp_ok) {
         ROOT::Math::IntegrationMultiDim::Type ig_type =
             utils::gsl::IntegrationNDimTypeFromString(fGSLIntgType);
         double abstol = 1; //We mostly care about relative tolerance.
         ROOT::Math::IntegratorMultiDim ig(*func, ig_type, abstol, fGSLRelTol, fGSLMaxEval);
 
         if (ig_type == ROOT::Math::IntegrationMultiDim::kADAPTIVE) {
            ROOT::Math::AdaptiveIntegratorMultiDim * cast =
              dynamic_cast<ROOT::Math::AdaptiveIntegratorMultiDim*>( ig.GetIntegrator() );
            assert(cast);
            cast->SetMinPts(fGSLMinEval);
         }
 
         double kine_min[2] = { Wl.min, Q2l.min };
         double kine_max[2] = { Wl.max, Q2l.max };
         xsec = ig.Integral(kine_min, kine_max) * (1E-38 * units::cm2);
       }// phase space limits ok?
    }//Ev>threshold
 
    LOG("DISXSec", pNOTICE)
       << "Caching: XSec[DIS] (E = " << Ev << " GeV) = "
       << xsec / (1E-38 * units::cm2) << " x 1E-38 cm^2";
    cache_branch->AddValues(Ev,xsec);
  }//ie
 
  // Create the spline
  cache_branch->CreateSpline();
 
  delete [] E;
  delete func;
}

References genie::Cache::AddCacheBranch(), genie::CacheBranchFx::AddValues(), CacheBranchName(), genie::units::cm2, genie::CacheBranchFx::CreateSpline(), genie::XSecIntegratorI::fGSLIntgType, genie::XSecIntegratorI::fGSLMaxEval, genie::XSecIntegratorI::fGSLMinEval, genie::XSecIntegratorI::fGSLRelTol, genie::Cache::FindCacheBranch(), func(), fVldEmax, fVldEmin, genie::Target::HitNucPdg(), genie::Interaction::InitStatePtr(), genie::Cache::Instance(), genie::utils::gsl::IntegrationNDimTypeFromString(), genie::pdg::IsProton(), genie::controls::kASmallNum, genie::kPdgTgtFreeN, genie::kPdgTgtFreeP, LOG, genie::Range1D_t::max, genie::Range1D_t::min, genie::Interaction::PhaseSpace(), pINFO, pNOTICE, pWARN, genie::KPhaseSpace::Q2Lim(), genie::Target::SetId(), genie::InitialState::SetProbeP4(), genie::InitialState::TgtPtr(), genie::KPhaseSpace::Threshold(), and genie::KPhaseSpace::WLim().

Referenced by Integrate().

Configure() [1/2]

void DISXSec::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 181 of file DISXSec.cxx.

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

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

Configure() [2/2]

void DISXSec::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 187 of file DISXSec.cxx.

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

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

Integrate()

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

virtual

XSecIntegratorI interface implementation.

Implements genie::XSecIntegratorI.

Definition at line 56 of file DISXSec.cxx.

{
  if(! model->ValidProcess(in) ) return 0.;
 
  const KPhaseSpace & kps = in->PhaseSpace();
  if(!kps.IsAboveThreshold()) {
     LOG("DISXSec", pDEBUG)  << "*** Below energy threshold";
     return 0;
  }
 
  const InitialState & init_state = in->InitState();
  double Ev = init_state.ProbeE(kRfHitNucRest);
 
  int nucpdgc = init_state.Tgt().HitNucPdg();
  int NNucl   = (pdg::IsProton(nucpdgc)) ?
                   init_state.Tgt().Z() : init_state.Tgt().N();
 
  // If the input interaction is off a nuclear target, then chek whether
  // the corresponding free nucleon cross section already exists at the
  // cross section spline list.
  // If yes, calculate the nuclear cross section based on that value.
  //
  XSecSplineList * xsl = XSecSplineList::Instance();
  if(init_state.Tgt().IsNucleus() && !xsl->IsEmpty() ) {
    Interaction * interaction = new Interaction(*in);
    Target * target = interaction->InitStatePtr()->TgtPtr();
    if(pdg::IsProton(nucpdgc)) { target->SetId(kPdgTgtFreeP); }
    else                       { target->SetId(kPdgTgtFreeN); }
    if(xsl->SplineExists(model,interaction)) {
      const Spline * spl = xsl->GetSpline(model, interaction);
      double xsec = spl->Evaluate(Ev);
      LOG("DISXSec", pINFO)
        << "From XSecSplineList: XSec[DIS,free nucleon] (E = " << Ev << " GeV) = " << xsec;
      if(! interaction->TestBit(kIAssumeFreeNucleon) ) {
          xsec *= NNucl;
          LOG("DISXSec", pINFO)  << "XSec[DIS] (E = " << Ev << " GeV) = " << xsec;
      }
      delete interaction;
      return xsec;
    }
    delete interaction;
  }
 
  // There was no corresponding free nucleon spline saved in XSecSplineList that
  // could be used to speed up this calculation.
  // Check whether local caching of free nucleon cross sections is allowed.
  // If yes, store free nucleon cross sections at a cache branch and use those
  // at any subsequent call.
  //
  bool precalc_bare_xsec = RunOpt::Instance()->BareXSecPreCalc();
  if(precalc_bare_xsec) {
     Cache * cache = Cache::Instance();
     Interaction * interaction = new Interaction(*in);
     string key = this->CacheBranchName(model,interaction);
     LOG("DISXSec", pINFO) << "Finding cache branch with key: " << key;
     CacheBranchFx * cache_branch =
           dynamic_cast<CacheBranchFx *> (cache->FindCacheBranch(key));
     if(!cache_branch) {
         this->CacheFreeNucleonXSec(model,interaction);
         cache_branch =
           dynamic_cast<CacheBranchFx *> (cache->FindCacheBranch(key));
         assert(cache_branch);
     }
     const CacheBranchFx & cb = (*cache_branch);
     double xsec = cb(Ev);
     if(! interaction->TestBit(kIAssumeFreeNucleon) ) { xsec *= NNucl; }
     LOG("DISXSec", pINFO)  << "XSec[DIS] (E = " << Ev << " GeV) = " << xsec;
     delete interaction;
     return xsec;
  }
  else {
    // Just go ahead and integrate the input differential cross section for the
    // specified interaction.
    //
     Interaction * interaction = new Interaction(*in);
     interaction->SetBit(kISkipProcessChk);
//   interaction->SetBit(kISkipKinematicChk);
 
     // **Important note**
     // Based on discussions with Hugh at the GENIE mini-workshop / RAL - July '07
     // The DIS nuclear corrections re-distribute the strength in x,y but do not
     // affect the total cross-section They should be disabled at this step.
     // But they should be enabled at the DIS thread's kinematical selection.
     // Since nuclear corrections don't need to be included at this stage, all the
     // nuclear cross sections can be trivially built from the free nucleon ones.
     //
     interaction->SetBit(kINoNuclearCorrection);
 
     Range1D_t Wl  = kps.WLim();
     Range1D_t Q2l = kps.Q2Lim();
     LOG("DISXSec", pINFO)
            << "W integration range = [" << Wl.min << ", " << Wl.max << "]";
     LOG("DISXSec", pINFO)
         << "Q2 integration range = [" << Q2l.min << ", " << Q2l.max << "]";
 
     bool phsp_ok =
          (Q2l.min >= 0. && Q2l.max >= 0. && Q2l.max >= Q2l.min &&
            Wl.min >= 0. &&  Wl.max >= 0. &&  Wl.max >=  Wl.min);
 
     double xsec = 0.;
 
     if(phsp_ok) {
       ROOT::Math::IBaseFunctionMultiDim * func =
          new utils::gsl::d2XSec_dWdQ2_E(model, interaction);
       ROOT::Math::IntegrationMultiDim::Type ig_type =
           utils::gsl::IntegrationNDimTypeFromString(fGSLIntgType);
 
       double abstol = 1; //We mostly care about relative tolerance.
       ROOT::Math::IntegratorMultiDim ig(*func, ig_type, abstol, fGSLRelTol, fGSLMaxEval);
       double kine_min[2] = { Wl.min, Q2l.min };
       double kine_max[2] = { Wl.max, Q2l.max };
       xsec = ig.Integral(kine_min, kine_max) * (1E-38 * units::cm2);
       delete func;
     }//phase space ok?
 
     LOG("DISXSec", pINFO)  << "XSec[DIS] (E = " << Ev << " GeV) = " << xsec;
 
     delete interaction;
 
     return xsec;
  }
  return 0;
}

References genie::RunOpt::BareXSecPreCalc(), CacheBranchName(), CacheFreeNucleonXSec(), genie::units::cm2, genie::Spline::Evaluate(), genie::XSecIntegratorI::fGSLIntgType, genie::XSecIntegratorI::fGSLMaxEval, genie::XSecIntegratorI::fGSLRelTol, genie::Cache::FindCacheBranch(), func(), genie::XSecSplineList::GetSpline(), genie::Target::HitNucPdg(), genie::Interaction::InitState(), genie::Interaction::InitStatePtr(), genie::Cache::Instance(), genie::RunOpt::Instance(), genie::XSecSplineList::Instance(), genie::utils::gsl::IntegrationNDimTypeFromString(), genie::KPhaseSpace::IsAboveThreshold(), genie::XSecSplineList::IsEmpty(), genie::Target::IsNucleus(), genie::pdg::IsProton(), genie::kIAssumeFreeNucleon, genie::kINoNuclearCorrection, genie::kISkipProcessChk, genie::kPdgTgtFreeN, genie::kPdgTgtFreeP, genie::kRfHitNucRest, LOG, genie::Range1D_t::max, genie::Range1D_t::min, genie::Target::N(), pDEBUG, genie::Interaction::PhaseSpace(), pINFO, genie::InitialState::ProbeE(), genie::KPhaseSpace::Q2Lim(), genie::Target::SetId(), genie::XSecSplineList::SplineExists(), genie::InitialState::Tgt(), genie::InitialState::TgtPtr(), genie::XSecAlgorithmI::ValidProcess(), genie::KPhaseSpace::WLim(), and genie::Target::Z().

LoadConfig()

void DISXSec::LoadConfig ( void )

private

Definition at line 193 of file DISXSec.cxx.

{
  // Get GSL integration type & relative tolerance
  GetParamDef("gsl-integration-type", fGSLIntgType, string("adaptive") ) ;
  GetParamDef( "gsl-relative-tolerance", fGSLRelTol, 1E-2 ) ;
 
  int max_eval, min_eval ;
  GetParamDef( "gsl-max-eval", max_eval, 500000 ) ;
  GetParamDef( "gsl-min-eval", min_eval, 10000 ) ;
 
  fGSLMaxEval  = (unsigned int) max_eval ;
  fGSLMinEval  = (unsigned int) min_eval ;
 
  // Energy range for cached splines
  GetParam( "GVLD-Emin", fVldEmin) ;
  GetParam( "GVLD-Emax", fVldEmax) ;
 
}

References genie::XSecIntegratorI::fGSLIntgType, genie::XSecIntegratorI::fGSLMaxEval, genie::XSecIntegratorI::fGSLMinEval, genie::XSecIntegratorI::fGSLRelTol, fVldEmax, fVldEmin, genie::Algorithm::GetParam(), and genie::Algorithm::GetParamDef().

Referenced by Configure(), and Configure().

Member Data Documentation

fVldEmax

double genie::DISXSec::fVldEmax

private

Definition at line 48 of file DISXSec.h.

Referenced by CacheFreeNucleonXSec(), and LoadConfig().

fVldEmin

double genie::DISXSec::fVldEmin

private

Definition at line 47 of file DISXSec.h.

Referenced by CacheFreeNucleonXSec(), and LoadConfig().

---

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

• DISXSec.h
• DISXSec.cxx