Generates kinematics for diffractive reactions. Is a concrete implementation of the EventRecordVisitorI interface. More...

#include <DFRKinematicsGenerator.h>

Inheritance diagram for genie::DFRKinematicsGenerator:

Public Member Functions
	DFRKinematicsGenerator ()

	DFRKinematicsGenerator (string config)

	~DFRKinematicsGenerator ()

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 *interaction) const

Private Attributes
double	fBeta

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 kinematics for diffractive reactions. Is a concrete implementation of the EventRecordVisitorI interface.

Author: Costas Andreopoulos <constantinos.andreopoulos cern.ch> University of Liverpool & STFC Rutherford Appleton Laboratory

Feb 15, 2009

Definition at line 27 of file DFRKinematicsGenerator.h.

Constructor & Destructor Documentation

DFRKinematicsGenerator::DFRKinematicsGenerator ( )

Definition at line 39 of file DFRKinematicsGenerator.cxx.

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

DFRKinematicsGenerator::DFRKinematicsGenerator ( string config )

Definition at line 45 of file DFRKinematicsGenerator.cxx.

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

DFRKinematicsGenerator::~DFRKinematicsGenerator ( )

Definition at line 51 of file DFRKinematicsGenerator.cxx.

 {
 
 }

Member Function Documentation

double DFRKinematicsGenerator::ComputeMaxXSec ( const Interaction * interaction ) const

privatevirtual

Implements genie::KineGeneratorWithCache.

Definition at line 250 of file DFRKinematicsGenerator.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 this needs to be fast - do not use a very fine grid.
 
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
   LOG("DFRKinematics", pDEBUG)
       << "Computing max xsec in allowed phase space";
 #endif
   double max_xsec = 0.0;
 
   const KPhaseSpace & kps = interaction->PhaseSpace();
   Range1D_t xl  = kps.XLim();
   Range1D_t yl  = kps.YLim();
   Range1D_t Wl  = kps.WLim();
 
   int    Ny      = 20;
   int    Nx      = 20;
   int    Nt      = 10;
   double xmin    = xl.min;
   double xmax    = xl.max;
   double ymin    = yl.min;
   double ymax    = yl.max;
   double dx      = (xmax-xmin)/(Nx-1);
   double dy      = (ymax-ymin)/(Ny-1);
 
 
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
   LOG("DFRKinematics", pDEBUG)
     << "Searching max. in x [" << xmin << ", " << xmax
     << "], y [" << ymin << ", " << ymax << "], z [" << zmin << ", " << zmax << "]";
 #endif
   double xseclast_y = -1;
   bool increasing_y;
 
   for(int i=0; i<Ny; i++) {
      double gy = ymin + i*dy;
      interaction->KinePtr()->Sety(gy);
 
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
      LOG("DFRKinematics", pDEBUG) << "y = " << gy;
 #endif
      for(int j=0; j<Nx; j++) {
         double gx = xmin + j*dx;
         interaction->KinePtr()->Setx(gx);
         kinematics::UpdateWQ2FromXY(interaction);
         Range1D_t Q2l = kps.Q2Lim_W();
 
         // the t range depends on x and y,
         // and you get NaNs if you try to calculate t
         // for an unphysical (x,y) combination
         bool in_phys = math::IsWithinLimits(interaction->KinePtr()->W(), Wl);
         in_phys = in_phys && math::IsWithinLimits(interaction->KinePtr()->Q2(), Q2l);
         if (!in_phys)
           continue;
 
         // t range depends on x and y
         Range1D_t tl = kps.TLim();
         double tmin    = tl.min;
         double tmax    = tl.max;
         double dt      = (tmax-tmin)/(Nt-1);
         for(int k=0; k<Nt; k++) {
           double gt = tmin + k*dt;
           interaction->KinePtr()->Sett(gt);
 
           double xsec = fXSecModel->XSec(interaction, kPSxytfE);
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
           LOG("DFRKinematics", pINFO)
             << "xsec(y=" << gy << ", x=" << gx << ", t=" << gt << ") = " << xsec;
 #endif
           // update maximum xsec
           max_xsec = TMath::Max(xsec, max_xsec);
         } // t
       } // x
     increasing_y = max_xsec-xseclast_y>=0;
     xseclast_y   = max_xsec;
     if(!increasing_y) {
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
       LOG("DFRKinematics", pDEBUG)
         << "d2xsec/dxdy stopped increasing. Exiting y loop";
 #endif
       break;
     }
   }// y
 
   // Apply safety factor, since value retrieved from the cache might
   // correspond to a slightly different energy
   max_xsec *= 3;
 
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
   SLOG("DFRKinematics", pDEBUG) << interaction->AsString();
   SLOG("DFRKinematics", pDEBUG) << "Max xsec in phase space = " << max_xsec;
   SLOG("DFRKinematics", pDEBUG) << "Computed using alg = " << *fXSecModel;
 #endif
 
   return max_xsec;
 }

void DFRKinematicsGenerator::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 213 of file DFRKinematicsGenerator.cxx.

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

void DFRKinematicsGenerator::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 219 of file DFRKinematicsGenerator.cxx.

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

void DFRKinematicsGenerator::LoadConfig ( void )

private

Definition at line 225 of file DFRKinematicsGenerator.cxx.

 {
 // Reads its configuration data from its configuration Registry and loads them
 // in private data members to avoid looking up at the Registry all the time.
 
   //-- 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, 0.8 ) ;
 
   //-- 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 ) ;
 
   GetParam( "DFR-Beta", fBeta ) ;
 
 }

void DFRKinematicsGenerator::ProcessEventRecord ( GHepRecord * event_rec ) const

virtual

Implements genie::EventRecordVisitorI.

Definition at line 56 of file DFRKinematicsGenerator.cxx.

 {
   if(fGenerateUniformly) {
     LOG("DFRKinematics", 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
   Interaction * interaction = evrec->Summary();
   interaction->SetBit(kISkipProcessChk);
 
   //-- Get neutrino energy and hit 'nucleon mass'
   const InitialState & init_state = interaction->InitState();
   double Ev  = init_state.ProbeE(kRfHitNucRest);
   double M   = init_state.Tgt().HitNucP4().M(); // can be off m-shell
 
   //-- Get the physical W range
   const KPhaseSpace & kps = interaction->PhaseSpace();
 
   Range1D_t xl = kps.Limits(kKVx);
   Range1D_t yl = kps.Limits(kKVy);
 
   // Note that the t limits used here are NOT the same as what you get from KPhaseSpace::TLim().
   // We use a larger range here because the limits from KPhaseSpace::TLim() depend on x and y,
   // and using the rejection method in a region that's changing depending on some of the
   // values guarantees that some regions will be oversampled.  We want to avoid that.
   Range1D_t tl;
   tl.min = 0;
   tl.max = KPhaseSpace::GetTMaxDFR();
 
   LOG("DFRKinematics", pNOTICE) << "x: [" << xl.min << ", " << xl.max << "]";
   LOG("DFRKinematics", pNOTICE) << "y: [" << yl.min << ", " << yl.max << "]";
   LOG("DFRKinematics", pNOTICE) << "t: [" << tl.min << ", " << tl.max << "]";
 
 /*
   Range1D_t W  = kps.Limits(kKVW);
   if(W.max <=0 || W.min>=W.max) {
      LOG("DFRKinematics", pWARN) << "No available phase space";
      evrec->EventFlags()->SetBitNumber(kKineGenErr, true);
      genie::exceptions::EVGThreadException exception;
      exception.SetReason("No available phase space");
      exception.SwitchOnFastForward();
      throw exception;
   }
 */
 
   assert(xl.min>0 && yl.min>0);
 
   //-- 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);
 
   //-- Try to select a valid (x,y,t) triplet using the rejection method
 
   double dx = xl.max - xl.min;
   double dy = yl.max - yl.min;
   double dt = tl.max - tl.min;
   double gx=-1, gy=-1, gt=-1, gW=-1, gQ2=-1, xsec=-1;
 
   unsigned int iter = 0;
   bool accept = false;
   while(true) {
      iter++;
      if(iter > kRjMaxIterations) {
        LOG("DFRKinematics", pWARN)
          << " Couldn't select kinematics after " << iter << " iterations";
        evrec->EventFlags()->SetBitNumber(kKineGenErr, true);
        genie::exceptions::EVGThreadException exception;
        exception.SetReason("Couldn't select kinematics");
        exception.SwitchOnFastForward();
        throw exception;
      }
 
      //-- random x,y,t
      gx = xl.min + dx * rnd->RndKine().Rndm();
      gy = yl.min + dy * rnd->RndKine().Rndm();
      gt = tl.min + dt * rnd->RndKine().Rndm();
 
      interaction->KinePtr()->Setx(gx);
      interaction->KinePtr()->Sety(gy);
      interaction->KinePtr()->Sett(gt);
 
      LOG("DFRKinematics", pDEBUG)
        << "Trying: x = " << gx << ", y = " << gy << ", t = " << gt;
 
      //-- compute the cross section for current kinematics
      xsec = fXSecModel->XSec(interaction, kPSxytfE);
 
      //-- decide whether to accept the current kinematics
      if(!fGenerateUniformly) {
         this->AssertXSecLimits(interaction, xsec, xsec_max);
         double n = xsec_max * rnd->RndKine().Rndm();
         double J = 1;
 
 #ifdef __GENIE_LOW_LEVEL_MESG_ENABLED__
         LOG("DFRKinematics", pDEBUG)
               << "xsec= " << xsec << ", J= " << J << ", Rnd= " << n;
 #endif
         accept = (n < J*xsec);
      }
      else {
        accept = (xsec>0);
      }
 
      //-- If the generated kinematics are accepted, finish-up module's job
      if(accept) {
          // reset trust bits
          interaction->ResetBit(kISkipProcessChk);
          interaction->ResetBit(kISkipKinematicChk);
 
          // for uniform kinematics, compute an event weight as
          // wght = (phase space volume)*(differential xsec)/(event total xsec)
          if(fGenerateUniformly) {
             double vol     = kinematics::PhaseSpaceVolume(interaction,kPSxytfE);
             double totxsec = evrec->XSec();
             double wght    = (vol/totxsec)*xsec;
             LOG("DFRKinematics", pNOTICE)  << "Kinematics wght = "<< wght;
 
             // apply computed weight to the current event weight
             wght *= evrec->Weight();
             LOG("DFRKinematics", pNOTICE) << "Current event wght = " << wght;
             evrec->SetWeight(wght);
          }
 
          // compute W,Q2 for selected x,y
          kinematics::XYtoWQ2(Ev,M,gW,gQ2,gx,gy);
 
          LOG("DFRKinematics", pNOTICE)
                 << "Selected x,y => W = " << gW << ", Q2 = " << gQ2;
 
          // set the cross section for the selected kinematics
          evrec->SetDiffXSec(xsec, kPSxytfE);
 
          // lock selected kinematics & clear running values
          interaction->KinePtr()->SetW (gW,  true);
          interaction->KinePtr()->SetQ2(gQ2, true);
          interaction->KinePtr()->Setx (gx,  true);
          interaction->KinePtr()->Sety (gy,  true);
          interaction->KinePtr()->Sett (gt,  true);
          interaction->KinePtr()->ClearRunningValues();
          return;
      }
   } // iterations
 }

Member Data Documentation

double genie::DFRKinematicsGenerator::fBeta

private

Definition at line 46 of file DFRKinematicsGenerator.h.

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

Generator/src/Physics/Diffractive/EventGen/DFRKinematicsGenerator.h
Generator/src/Physics/Diffractive/EventGen/DFRKinematicsGenerator.cxx

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation