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

#include <IBDKinematicsGenerator.h>

Inheritance diagram for genie::IBDKinematicsGenerator:

Public Member Functions
	IBDKinematicsGenerator ()

	IBDKinematicsGenerator (string config)

virtual	~IBDKinematicsGenerator ()

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. 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)

double	ComputeMaxXSec (const Interaction *in) const

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

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

Author: Corey Reed <cjreed nikhef.nl> - October 29, 2009 using code from the QELKinematicGenerator written by Costas Andreopoulos <constantinos.andreopoulos cern.ch> University of Liverpool & STFC Rutherford Appleton Laboratory

October 29, 2009

Definition at line 31 of file IBDKinematicsGenerator.h.

Constructor & Destructor Documentation

IBDKinematicsGenerator::IBDKinematicsGenerator ( )

Definition at line 41 of file IBDKinematicsGenerator.cxx.

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

IBDKinematicsGenerator::IBDKinematicsGenerator ( string config )

Definition at line 47 of file IBDKinematicsGenerator.cxx.

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

IBDKinematicsGenerator::~IBDKinematicsGenerator ( )

virtual

Definition at line 53 of file IBDKinematicsGenerator.cxx.

 {
 
 }

Member Function Documentation

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

privatevirtual

Implements genie::KineGeneratorWithCache.

Definition at line 242 of file IBDKinematicsGenerator.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 a very small dQ2 step.
 
   double max_xsec = 0.0;
 
   const KPhaseSpace & kps = interaction->PhaseSpace();
   Range1D_t rQ2 = kps.Limits(kKVQ2);
   if(rQ2.min <=0 || rQ2.max <= rQ2.min) return 0.;
 
   //const double logQ2min = TMath::Log(rQ2.min + kASmallNum);
   //const double logQ2max = TMath::Log(rQ2.max - kASmallNum);
   const double logQ2min = TMath::Log(rQ2.min);
   const double logQ2max = TMath::Log(rQ2.max);
 
   const int N  = 15;
   const int Nb = 10;
 
   double dlogQ2   = (logQ2max - logQ2min) /(N-1);
   double xseclast = -1;
   bool   increasing;
 
   for(int i=0; i<N; i++) {
      double Q2 = TMath::Exp(logQ2min + i * dlogQ2);
      interaction->KinePtr()->SetQ2(Q2);
      double xsec = fXSecModel->XSec(interaction, kPSQ2fE);
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
      LOG("IBD", pDEBUG)  << "xsec(Q2= " << Q2 << ") = " << xsec;
 #endif
      max_xsec = TMath::Max(xsec, max_xsec);
      increasing = xsec-xseclast>=0;
      xseclast   = xsec;
 
      // once the cross section stops increasing, I reduce the step size and
      // step backwards a little bit to handle cases that the max cross section
      // is grossly underestimated (very peaky distribution & large step)
      if(!increasing) {
        dlogQ2/=(Nb+1);
        for(int ib=0; ib<Nb; ib++) {
          Q2 = TMath::Exp(TMath::Log(Q2) - dlogQ2);
          if(Q2 < rQ2.min) continue;
          interaction->KinePtr()->SetQ2(Q2);
          xsec = fXSecModel->XSec(interaction, kPSQ2fE);
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
          LOG("IBD", pDEBUG)  << "xsec(Q2= " << Q2 << ") = " << xsec;
 #endif
          max_xsec = TMath::Max(xsec, max_xsec);
        }
        break;
      }
   }//Q^2
 
   // 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("IBD", pDEBUG) << interaction->AsString();
   SLOG("IBD", pDEBUG) << "Max xsec in phase space = " << max_xsec;
   SLOG("IBD", pDEBUG) << "Computed using alg = " << *fXSecModel;
 #endif
 
   return max_xsec;
 }

void IBDKinematicsGenerator::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 210 of file IBDKinematicsGenerator.cxx.

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

void IBDKinematicsGenerator::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 216 of file IBDKinematicsGenerator.cxx.

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

void IBDKinematicsGenerator::LoadConfig ( void )

private

Definition at line 222 of file IBDKinematicsGenerator.cxx.

 {
         //-- Safety factor for the maximum differential cross section
         GetParamDef( "MaxXSec-SafetyFactor", fSafetyFactor, 1.25 ) ;
 
         //-- 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 ) ;
 
 }

void IBDKinematicsGenerator::ProcessEventRecord ( GHepRecord * event_rec ) const

virtual

Implements genie::EventRecordVisitorI.

Definition at line 58 of file IBDKinematicsGenerator.cxx.

 {
   if(fGenerateUniformly) {
     LOG("IBD", pNOTICE)
           << "Generating kinematics uniformly over the allowed phase space";
   }
 
   //-- 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 set the 'trust' bits
   Interaction * interaction = evrec->Summary();
   interaction->SetBit(kISkipProcessChk);
   interaction->SetBit(kISkipKinematicChk);
 
   //-- Note: The kinematic generator would be using the free nucleon cross
   //   section (even for nuclear targets) so as not to double-count nuclear
   //   suppression. This assumes that a) the nuclear suppression was turned
   //   on when computing the cross sections for selecting the current event 
   //   and that b) if the event turns out to be unphysical (Pauli-blocked) 
   //   the next attempted event will be forced to QEL again.
   //   (discussion with Hugh - GENIE/NeuGEN integration workshop - 07APR2006
   interaction->SetBit(kIAssumeFreeNucleon);
 
   //-- Get the limits for the generated Q2
   const KPhaseSpace & kps = interaction->PhaseSpace();
   const Range1D_t Q2 = kps.Limits(kKVQ2);
   
   if(Q2.max <=0 || Q2.min>=Q2.max) {
      LOG("IBD", pWARN) << "No available phase space";
      evrec->EventFlags()->SetBitNumber(kKineGenErr, true);
      genie::exceptions::EVGThreadException exception;
      exception.SetReason("No available phase space");
      exception.SwitchOnFastForward();
      throw exception;
   }
 
   //-- 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
   const double xsec_max = (fGenerateUniformly) ? -1 : this->MaxXSec(evrec);
 
   //-- Try to select a valid Q2 using the rejection method
 
   // kinematical limits
   const double Q2min  = Q2.min;
   const double Q2max  = Q2.max;
   double xsec   = -1.;
   double gQ2    =  0.;
 
   unsigned int iter = 0;
   bool accept = false;
   while(1) {
      iter++;
      if(iter > kRjMaxIterations) {
         LOG("IBD", pWARN)
           << "Couldn't select a valid Q^2 after " << iter << " iterations";
         evrec->EventFlags()->SetBitNumber(kKineGenErr, true);
         genie::exceptions::EVGThreadException exception;
         exception.SetReason("Couldn't select kinematics");
         exception.SwitchOnFastForward();
         throw exception;
      }
      
      //-- Generate a Q2 value within the allowed phase space
      gQ2 = Q2min + (Q2max-Q2min) * rnd->RndKine().Rndm();
      interaction->KinePtr()->SetQ2(gQ2);
      LOG("IBD", pINFO) << "Trying: Q^2 = " << gQ2;
 
      //-- Computing cross section for the current kinematics
      xsec = fXSecModel->XSec(interaction, kPSQ2fE);
 
      //-- Decide whether to accept the current kinematics
      if(!fGenerateUniformly) {
         this->AssertXSecLimits(interaction, xsec, xsec_max);
         const double t = xsec_max * rnd->RndKine().Rndm();
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
         LOG("IBD", pDEBUG)
             << "dxsec/dQ2 = " << xsec << ", rnd = " << t;
 #endif
         accept = (t < xsec);
      } else {
         accept = (xsec>0);
      }
 
      //-- If the generated kinematics are accepted, finish-up module's job
      if(accept) {
         LOG("IBD", pINFO) << "Selected: Q^2 = " << gQ2;
 
         // reset bits
         interaction->ResetBit(kISkipProcessChk);
         interaction->ResetBit(kISkipKinematicChk);
         interaction->ResetBit(kIAssumeFreeNucleon);
 
         // compute the rest of the kinematical variables
 
         // 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();
         const double E = init_state.ProbeE(kRfHitNucRest);
         const double M = init_state.Tgt().HitNucP4().M();
 
         LOG("IBD", pNOTICE) << "E = " << E << ", M = "<< M;
 
         // The hadronic inv. mass is equal to the recoil nucleon on-shell mass.
         const int rpdgc = interaction->RecoilNucleonPdg();
         assert(rpdgc);
         const double gW = PDGLibrary::Instance()->Find(rpdgc)->Mass();
 
         LOG("IBD", pNOTICE) << "Selected: W = "<< gW;
 
         // (W,Q2) -> (x,y)
         double gx=0, gy=0;
         kinematics::WQ2toXY(E,M,gW,gQ2,gx,gy);
 
         // set the cross section for the selected kinematics
         evrec->SetDiffXSec(xsec,kPSQ2fE);
 
         // for uniform kinematics, compute an event weight as
         // wght = (phase space volume)*(differential xsec)/(event total xsec)
         if(fGenerateUniformly) {
            const double vol     = kinematics::PhaseSpaceVolume(interaction,kPSQ2fE);
            const double totxsec = evrec->XSec();
                  double wght    = (vol/totxsec)*xsec;
            LOG("IBD", pNOTICE)  << "Kinematics wght = "<< wght;
 
            // apply computed weight to the current event weight
            wght *= evrec->Weight();
            LOG("IBD", pNOTICE) << "Current event wght = " << wght;
            evrec->SetWeight(wght);
         }
 
         // 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();
 
         return;
      }
   }// iterations
 }

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

Generator/src/Physics/InverseBetaDecay/EventGen/IBDKinematicsGenerator.h
Generator/src/Physics/InverseBetaDecay/EventGen/IBDKinematicsGenerator.cxx

Public Member Functions

Private Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation