genie::rew::GReWeightNuXSecHelper Class Reference

Helper class for cross section model reweighting. More...

#include <GReWeightNuXSecHelper.h>

Public Member Functions
	GReWeightNuXSecHelper ()
	~GReWeightNuXSecHelper ()
void	HandleInitState (const InitialState &init_state)
void	DiffCrossSecType (ScatteringType_t sct, KinePhaseSpace_t kps)
double	NewWeight (const EventRecord &event, bool shape_only=false)

Private Member Functions
void	Initialize ()

Private Attributes
GEVGPool	fGPool
map< ScatteringType_t, KinePhaseSpace_t >	fCrossSecModelPhSp

Detailed Description

Helper class for cross section model reweighting.

Author

Costas Andreopoulos <costas.andreopoulos stfc.ac.uk> University of Liverpool & STFC Rutherford Appleton Lab

October 22, 2005

Copyright (c) 2003-2017, GENIE Neutrino MC Generator Collaboration For the full text of the license visit http://copyright.genie-mc.org or see $GENIE/LICENSE

Definition at line 36 of file GReWeightNuXSecHelper.h.

Constructor & Destructor Documentation

GReWeightNuXSecHelper::GReWeightNuXSecHelper

(

void

)

Definition at line 38 of file GReWeightNuXSecHelper.cxx.

{
  this->Initialize();
}

GReWeightNuXSecHelper::~GReWeightNuXSecHelper

(

void

)

Definition at line 43 of file GReWeightNuXSecHelper.cxx.

{

}

Member Function Documentation

void GReWeightNuXSecHelper::DiffCrossSecType	(	ScatteringType_t	sct,
		KinePhaseSpace_t	kps
	)

Definition at line 75 of file GReWeightNuXSecHelper.cxx.

{
  fCrossSecModelPhSp.insert(
     map<ScatteringType_t,KinePhaseSpace_t>::value_type(sct,kps));
}

void GReWeightNuXSecHelper::HandleInitState

(

const InitialState &

init_state

)

Definition at line 56 of file GReWeightNuXSecHelper.cxx.

{
  // form initial state filtering out any unwanted info
  InitialState init_state(is.TgtPdg(), is.ProbePdg()); 

  // check for an event generation configured for that initial state
  GEVGDriver * evg_driver = fGPool.FindDriver(init_state);

  // if none was found  then create/configure/store one now
  if(!evg_driver) {
    LOG("ReW", pNOTICE) 
        << "Adding event generation driver for initial state = " 
        << init_state.AsString();
    evg_driver = new GEVGDriver;
    evg_driver->Configure(init_state);
    fGPool.insert( GEVGPool::value_type(init_state.AsString(), evg_driver) );
  }
}

void GReWeightNuXSecHelper::Initialize ( void  )

private

Definition at line 48 of file GReWeightNuXSecHelper.cxx.

{
  this->DiffCrossSecType( kScQuasiElastic,    kPSQ2fE  );
  this->DiffCrossSecType( kScDeepInelastic,   kPSxyfE  );
  this->DiffCrossSecType( kScResonant,        kPSWQ2fE );
  this->DiffCrossSecType( kScCoherent,        kPSxyfE  );
}

double GReWeightNuXSecHelper::NewWeight	(	const EventRecord &	event,
		bool	shape_only = false
	)

Definition at line 82 of file GReWeightNuXSecHelper.cxx.

{
  // Get event summary (Interaction) from the input event
  assert(event.Summary());
  Interaction & interaction = * event.Summary();

  //LOG("ReW", pDEBUG) << "Computing new weight for: \n" << interaction;

  // Find the event generation driver that handles the given initial state
  const InitialState & init_state = interaction.InitState();
  GEVGDriver * evg_driver = fGPool.FindDriver(init_state);
  if(!evg_driver) {
    LOG("ReW", pINFO)
      << "Adding generator driver for init state: " << init_state.AsString();
    evg_driver = new GEVGDriver;
    evg_driver->Configure(init_state);
    fGPool.insert( GEVGPool::value_type(init_state.AsString(), evg_driver) );
  }
  assert(evg_driver);

  // Find the event generation thread that handles the given interaction
  const EventGeneratorI * evg_thread = evg_driver->FindGenerator(&interaction);
  if(!evg_thread) {
    LOG("ReW", pERROR)
      << "No event generator thread for interaction: " << interaction;
    return 0;
  }

  // Get the cross section model associated with that thread
  const XSecAlgorithmI * xsec_model = evg_thread->CrossSectionAlg();
  if(!xsec_model) {
    LOG("ReW", pERROR)
      << "No cross section model for interaction: " << interaction;
    return 0;
  }

  // Get the kinematical phase space used for computing the differential
  // cross sections stored in the event
  ScatteringType_t sct = interaction.ProcInfo().ScatteringTypeId();
  map<ScatteringType_t, KinePhaseSpace_t>::const_iterator 
                               kpsi = fCrossSecModelPhSp.find(sct); 

  if(kpsi == fCrossSecModelPhSp.end()) return 1;
  KinePhaseSpace_t kps = kpsi->second;
  if(kps==kPSNull) return 1;

  // Copy the 'selected' kinematics into the 'running' kinematics
  interaction.KinePtr()->UseSelectedKinematics();

  // hack to match what was stored during event generation
  // -- is currently revisited -- 
  if(interaction.ProcInfo().IsQuasiElastic()) 
                interaction.SetBit(kIAssumeFreeNucleon);

  double old_xsec   = event.DiffXSec();
  double old_weight = event.Weight();
  double new_xsec   = xsec_model->XSec(&interaction,kps);
  double new_weight = old_weight * (new_xsec/old_xsec);

  if(shape_only) {
    double old_integrated_xsec = event.XSec();
    double new_integrated_xsec = xsec_model->Integral(&interaction);
    assert(new_integrated_xsec > 0);
    new_weight *= (old_integrated_xsec/new_integrated_xsec);
  }

  // hack - closing parenthesis
  if(interaction.ProcInfo().IsQuasiElastic()) 
                interaction.ResetBit(kIAssumeFreeNucleon);

  // Clear the 'running' kinematics buffer
  interaction.KinePtr()->ClearRunningValues();

  LOG("ReW", pINFO)
     << "Event d{xsec}/dK : " << old_xsec   << " --> " << new_xsec;
  LOG("ReW", pINFO)
     << "Event weight     : " << old_weight << " ---> " << new_weight;

  return new_weight;
}

Member Data Documentation

map<ScatteringType_t, KinePhaseSpace_t> genie::rew::GReWeightNuXSecHelper::fCrossSecModelPhSp

private

Definition at line 51 of file GReWeightNuXSecHelper.h.

GEVGPool genie::rew::GReWeightNuXSecHelper::fGPool

private

Definition at line 50 of file GReWeightNuXSecHelper.h.

---

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

• GENIE/src/ReWeight/GReWeightNuXSecHelper.h
• GENIE/src/ReWeight/GReWeightNuXSecHelper.cxx