Utilities for simulating nucleon decay. More...

#include <NucleonDecayPrimaryVtxGenerator.h>

Inheritance diagram for genie::NucleonDecayPrimaryVtxGenerator:

Collaboration diagram for genie::NucleonDecayPrimaryVtxGenerator:

Public Member Functions
	NucleonDecayPrimaryVtxGenerator ()
	NucleonDecayPrimaryVtxGenerator (string config)
	~NucleonDecayPrimaryVtxGenerator ()
void	ProcessEventRecord (GHepRecord *event) 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.
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	AddInitialState (GHepRecord *event) const
void	GenerateDecayedNucleonPosition (GHepRecord *event) const
void	GenerateFermiMomentum (GHepRecord *event) const
void	GenerateDecayProducts (GHepRecord *event) const

Private Attributes
int	fCurrInitStatePdg
NucleonDecayMode_t	fCurrDecayMode
int	fCurrDecayedNucleon
bool	fNucleonIsBound
TGenPhaseSpace	fPhaseSpaceGenerator
const NuclearModelI *	fNuclModel

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::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.
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::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

Utilities for simulating nucleon decay.

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

Created:\n November 03, 2011

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 30 of file NucleonDecayPrimaryVtxGenerator.h.

Constructor & Destructor Documentation

◆ NucleonDecayPrimaryVtxGenerator() [1/2]

NucleonDecayPrimaryVtxGenerator::NucleonDecayPrimaryVtxGenerator ( )

Definition at line 34 of file NucleonDecayPrimaryVtxGenerator.cxx.

                                                                 :
EventRecordVisitorI("genie::NucleonDecayPrimaryVtxGenerator")
{
 
}

References genie::EventRecordVisitorI::EventRecordVisitorI().

◆ NucleonDecayPrimaryVtxGenerator() [2/2]

NucleonDecayPrimaryVtxGenerator::NucleonDecayPrimaryVtxGenerator ( string config )

Definition at line 40 of file NucleonDecayPrimaryVtxGenerator.cxx.

                 :
EventRecordVisitorI("genie::NucleonDecayPrimaryVtxGenerator",config)
{
 
}

References genie::EventRecordVisitorI::EventRecordVisitorI().

◆ ~NucleonDecayPrimaryVtxGenerator()

NucleonDecayPrimaryVtxGenerator::~NucleonDecayPrimaryVtxGenerator ( )

Definition at line 47 of file NucleonDecayPrimaryVtxGenerator.cxx.

{
 
}

Member Function Documentation

◆ AddInitialState()

void NucleonDecayPrimaryVtxGenerator::AddInitialState ( GHepRecord * event ) const

private

Definition at line 72 of file NucleonDecayPrimaryVtxGenerator.cxx.

{
//
// Add initial state in the event record.
//
// If the decayed nucleon is one bound in a nucleus, the event record is
// initialized as follows:
//    id: 0, nucleus (kIStInitialState)
//    |
//    |---> { id: 1, nucleon         (kIStDecayedState)
//          { id: 2, remnant nucleus (kIStStableFinalState)
//
// If the decayed nucleon is a free one, the event record is initialized as
// follows:
//    id: 0, nucleon (kIStInitialState)
//    |
//    |---> id: 1, nucleon (kIStDecayedState)
//
 
  TLorentzVector v4(0,0,0,0);
 
  GHepStatus_t stis = kIStInitialState;
  GHepStatus_t stdc = kIStDecayedState;
  GHepStatus_t stfs = kIStStableFinalState;
 
  int ipdg = fCurrInitStatePdg;
 
  // Decayed nucleon is a bound one.
  if(fNucleonIsBound)
  {
    // add initial nucleus
    double Mi  = PDGLibrary::Instance()->Find(ipdg)->Mass();
    TLorentzVector p4i(0,0,0,Mi);
    event->AddParticle(ipdg,stis,-1,-1,-1,-1, p4i, v4);
 
    // add decayed nucleon
    int dpdg = fCurrDecayedNucleon;
    double mn = PDGLibrary::Instance()->Find(dpdg)->Mass();
    TLorentzVector p4n(0,0,0,mn);
    event->AddParticle(dpdg,stdc, 0,-1,-1,-1, p4n, v4);
 
    // add nuclear remnant
    int A = pdg::IonPdgCodeToA(ipdg);
    int Z = pdg::IonPdgCodeToZ(ipdg);
    A--;
    if(dpdg == kPdgProton) { Z--; }
    int rpdg = pdg::IonPdgCode(A, Z);
    double Mf  = PDGLibrary::Instance()->Find(rpdg)->Mass();
    TLorentzVector p4f(0,0,0,Mf);
    event->AddParticle(rpdg,stfs,0,-1,-1,-1, p4f, v4);
  }
 
  // Decayed nucleon is a free one
  else
  {
    // Initial state is either a neutron or a proton.
    // Convert the initial state PDG code from the ion convention (10LZZZAAAI)
    // to the usual code for neutrons or protons
    int ipdg_short = -1;
    if(ipdg == kPdgTgtFreeP) ipdg_short = kPdgProton;
    if(ipdg == kPdgTgtFreeN) ipdg_short = kPdgNeutron;
 
    // Decayed nucleon code
    int dpdg = fCurrDecayedNucleon;
 
    if(dpdg != ipdg_short) {
       LOG("NucleonDecay", pWARN)
           << "Couldn't generate given decay ("
           << utils::nucleon_decay::AsString(fCurrDecayMode, fCurrDecayedNucleon) << ")"
           << " for given initial state (PDG = " << ipdg_short << ")";
       genie::exceptions::EVGThreadException exception;
       exception.SetReason("Decay-mode / Initial-state mismatch!");
       exception.SwitchOnFastForward();
       throw exception;
    }
    // add initial nucleon
    double mn  = PDGLibrary::Instance()->Find(ipdg)->Mass();
    TLorentzVector p4i(0,0,0,mn);
    event->AddParticle(dpdg,stis,-1,-1,-1,-1, p4i, v4);
    // add decayed nucleon
    event->AddParticle(dpdg,stdc,0,-1,-1,-1, p4i, v4);
  }
}

References genie::utils::nucleon_decay::AsString(), fCurrDecayedNucleon, fCurrDecayMode, fCurrInitStatePdg, genie::PDGLibrary::Find(), fNucleonIsBound, genie::PDGLibrary::Instance(), genie::pdg::IonPdgCode(), genie::pdg::IonPdgCodeToA(), genie::pdg::IonPdgCodeToZ(), genie::kIStDecayedState, genie::kIStInitialState, genie::kIStStableFinalState, genie::kPdgNeutron, genie::kPdgProton, genie::kPdgTgtFreeN, genie::kPdgTgtFreeP, LOG, pWARN, genie::exceptions::EVGThreadException::SetReason(), and genie::exceptions::EVGThreadException::SwitchOnFastForward().

Referenced by ProcessEventRecord().

◆ Configure() [1/2]

void NucleonDecayPrimaryVtxGenerator::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 392 of file NucleonDecayPrimaryVtxGenerator.cxx.

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

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

◆ Configure() [2/2]

void NucleonDecayPrimaryVtxGenerator::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 398 of file NucleonDecayPrimaryVtxGenerator.cxx.

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

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

◆ GenerateDecayedNucleonPosition()

void NucleonDecayPrimaryVtxGenerator::GenerateDecayedNucleonPosition ( GHepRecord * event ) const

private

Definition at line 157 of file NucleonDecayPrimaryVtxGenerator.cxx.

{
  GHepParticle * initial_nucleus = event->Particle(0);
  int A = initial_nucleus->A();
  if(A <= 2) {
    return;
  }
 
  RandomGen * rnd = RandomGen::Instance();
 
  double R0 = 1.3;
  double dA = (double)A;
  double R = R0 * TMath::Power(dA, 1./3.);
 
  LOG("NucleonDecay", pINFO)
      << "Generating vertex according to a realistic nuclear density profile";
 
  // get inputs to the rejection method
  double ymax = -1;
  double rmax = 3*R;
  double dr   = R/40.;
  for(double r = 0; r < rmax; r+=dr) {
      ymax = TMath::Max(ymax, r*r * utils::nuclear::Density(r,A));
  }
  ymax *= 1.2;
 
  // select a vertex using the rejection method
  TLorentzVector vtx(0,0,0,0);
  unsigned int iter = 0;
  while(1) {
    iter++;
 
    // throw an exception if it hasn't find a solution after many attempts
    if(iter > controls::kRjMaxIterations) {
       LOG("NucleonDecay", pWARN)
           << "Couldn't generate a vertex position after " << iter << " iterations";
       genie::exceptions::EVGThreadException exception;
       exception.SetReason("Couldn't generate vertex");
       exception.SwitchOnFastForward();
       throw exception;
    }
 
    double r = rmax * rnd->RndFsi().Rndm();
    double t = ymax * rnd->RndFsi().Rndm();
    double y = r*r * utils::nuclear::Density(r,A);
    if(y > ymax) {
       LOG("NucleonDecay", pERROR)
          << "y = " << y << " > ymax = " << ymax << " for r = " << r << ", A = " << A;
    }
    bool accept = (t < y);
    if(accept) {
       double phi      = 2*constants::kPi * rnd->RndFsi().Rndm();
       double cosphi   = TMath::Cos(phi);
       double sinphi   = TMath::Sin(phi);
       double costheta = -1 + 2 * rnd->RndFsi().Rndm();
       double sintheta = TMath::Sqrt(1-costheta*costheta);
       vtx.SetX(r*sintheta*cosphi);
       vtx.SetY(r*sintheta*sinphi);
       vtx.SetZ(r*costheta);
       vtx.SetT(0.);
       break;
    }
  } // while 1
 
  GHepParticle * decayed_nucleon = event->Particle(1);
  assert(decayed_nucleon);
  decayed_nucleon->SetPosition(vtx);
}

References genie::GHepParticle::A(), genie::utils::nuclear::Density(), genie::RandomGen::Instance(), genie::constants::kPi, genie::controls::kRjMaxIterations, LOG, pERROR, pINFO, pWARN, genie::RandomGen::RndFsi(), genie::GHepParticle::SetPosition(), genie::exceptions::EVGThreadException::SetReason(), and genie::exceptions::EVGThreadException::SwitchOnFastForward().

Referenced by ProcessEventRecord().

◆ GenerateDecayProducts()

void NucleonDecayPrimaryVtxGenerator::GenerateDecayProducts ( GHepRecord * event ) const

private

accept_decay

Definition at line 269 of file NucleonDecayPrimaryVtxGenerator.cxx.

{
  LOG("NucleonDecay", pINFO) << "Generating decay...";
 
  PDGCodeList pdgv = utils::nucleon_decay::DecayProductList(fCurrDecayMode, fCurrDecayedNucleon);
  LOG("NucleonDecay", pINFO) << "Decay product IDs: " << pdgv;
  assert ( pdgv.size() >  1);
 
  LOG("NucleonDecay", pINFO) << "Performing a phase space decay...";
 
  // Get the decay product masses
 
  vector<int>::const_iterator pdg_iter;
  int i = 0;
  double * mass = new double[pdgv.size()];
  double   sum  = 0;
  for(pdg_iter = pdgv.begin(); pdg_iter != pdgv.end(); ++pdg_iter) {
    int pdgc = *pdg_iter;
    double m = PDGLibrary::Instance()->Find(pdgc)->Mass();
    mass[i++] = m;
    sum += m;
  }
 
  LOG("NucleonDecay", pINFO)
    << "Decaying N = " << pdgv.size() << " particles / total mass = " << sum;
 
  int decayed_nucleon_id = 1;
  GHepParticle * decayed_nucleon = event->Particle(decayed_nucleon_id);
  assert(decayed_nucleon);
  TLorentzVector * p4d = decayed_nucleon->GetP4();
  TLorentzVector * v4d = decayed_nucleon->GetX4();
 
  LOG("NucleonDecay", pINFO)
    << "Decaying system p4 = " << utils::print::P4AsString(p4d);
 
  // Set the decay
  bool permitted = fPhaseSpaceGenerator.SetDecay(*p4d, pdgv.size(), mass);
  if(!permitted) {
     LOG("NucleonDecay", pERROR)
       << " *** Phase space decay is not permitted \n"
       << " Total particle mass = " << sum << "\n"
       << " Decaying system p4 = " << utils::print::P4AsString(p4d);
     // clean-up
     delete [] mass;
     delete p4d;
     delete v4d;
     // throw exception
     genie::exceptions::EVGThreadException exception;
     exception.SetReason("Decay not permitted kinematically");
     exception.SwitchOnFastForward();
     throw exception;
  }
 
  // Get the maximum weight
  //double wmax = fPhaseSpaceGenerator.GetWtMax();
  double wmax = -1;
  for(int idec=0; idec<200; idec++) {
     double w = fPhaseSpaceGenerator.Generate();
     wmax = TMath::Max(wmax,w);
  }
  assert(wmax>0);
  wmax *= 2;
 
  LOG("NucleonDecay", pNOTICE)
     << "Max phase space gen. weight @ current hadronic system: " << wmax;
 
  // Generate an unweighted decay
  RandomGen * rnd = RandomGen::Instance();
 
  bool accept_decay=false;
  unsigned int itry=0;
  while(!accept_decay)
  {
     itry++;
 
     if(itry > controls::kMaxUnweightDecayIterations) {
       // report, clean-up and return
       LOG("NucleonDecay", pWARN)
           << "Couldn't generate an unweighted phase space decay after "
           << itry << " attempts";
       // clean up
       delete [] mass;
       delete p4d;
       delete v4d;
       // throw exception
       genie::exceptions::EVGThreadException exception;
       exception.SetReason("Couldn't select decay after N attempts");
       exception.SwitchOnFastForward();
       throw exception;
     }
     double w  = fPhaseSpaceGenerator.Generate();
     if(w > wmax) {
        LOG("NucleonDecay", pWARN)
           << "Decay weight = " << w << " > max decay weight = " << wmax;
     }
     double gw = wmax * rnd->RndHadro().Rndm();
     accept_decay = (gw<=w);
 
     LOG("NucleonDecay", pINFO)
        << "Decay weight = " << w << " / R = " << gw
        << " - accepted: " << accept_decay;
 
  } //!accept_decay
 
  // Insert final state products into a TClonesArray of GHepParticle's
  TLorentzVector v4(*v4d);
  int idp = 0;
  for(pdg_iter = pdgv.begin(); pdg_iter != pdgv.end(); ++pdg_iter) {
     int pdgc = *pdg_iter;
     TLorentzVector * p4fin = fPhaseSpaceGenerator.GetDecay(idp);
     GHepStatus_t ist =
        utils::nucleon_decay::DecayProductStatus(fNucleonIsBound, pdgc);
     event->AddParticle(pdgc, ist, decayed_nucleon_id,-1,-1,-1, *p4fin, v4);
     idp++;
  }
 
  // Clean-up
  delete [] mass;
  delete p4d;
  delete v4d;
}

References genie::utils::nucleon_decay::DecayProductList(), genie::utils::nucleon_decay::DecayProductStatus(), fCurrDecayedNucleon, fCurrDecayMode, genie::PDGLibrary::Find(), fNucleonIsBound, fPhaseSpaceGenerator, genie::GHepParticle::GetP4(), genie::GHepParticle::GetX4(), genie::PDGLibrary::Instance(), genie::RandomGen::Instance(), genie::controls::kMaxUnweightDecayIterations, LOG, genie::utils::print::P4AsString(), pERROR, pINFO, pNOTICE, pWARN, genie::RandomGen::RndHadro(), genie::exceptions::EVGThreadException::SetReason(), and genie::exceptions::EVGThreadException::SwitchOnFastForward().

Referenced by ProcessEventRecord().

◆ GenerateFermiMomentum()

void NucleonDecayPrimaryVtxGenerator::GenerateFermiMomentum ( GHepRecord * event ) const

private

Definition at line 227 of file NucleonDecayPrimaryVtxGenerator.cxx.

{
  GHepParticle * initial_nucleus = event->Particle(0);
  int A = initial_nucleus->A();
  if(A <= 2) {
    return;
  }
 
  GHepParticle * decayed_nucleon = event->Particle(1);
  GHepParticle * remnant_nucleus = event->Particle(2);
  assert(decayed_nucleon);
  assert(remnant_nucleus);
 
  // generate a Fermi momentum & removal energy
  Target tgt(initial_nucleus->Pdg());
  tgt.SetHitNucPdg(decayed_nucleon->Pdg());
  fNuclModel->GenerateNucleon(tgt);
  TVector3 p3 = fNuclModel->Momentum3();
  double w    = fNuclModel->RemovalEnergy();
 
  LOG("FermiMover", pINFO)
     << "Generated nucleon momentum: ("
     << p3.Px() << ", " << p3.Py() << ", " << p3.Pz() << "), "
     << "|p| = " << p3.Mag();
  LOG("NucleonDecay", pINFO)
     << "Generated nucleon removal energy: w = " << w;
 
  double pF2 = p3.Mag2(); // (fermi momentum)^2
 
  double Mi  = PDGLibrary::Instance()->Find(initial_nucleus->Pdg())-> Mass(); // initial nucleus mass
  double Mf  = PDGLibrary::Instance()->Find(remnant_nucleus->Pdg())-> Mass(); // remnant nucleus mass
 
  double EN = Mi - TMath::Sqrt(pF2 + Mf*Mf);
 
  TLorentzVector p4nucleon(   p3.Px(),    p3.Py(),    p3.Pz(), EN);
  TLorentzVector p4remnant(-1*p3.Px(), -1*p3.Py(), -1*p3.Pz(), Mi-EN);
 
  decayed_nucleon->SetMomentum(p4nucleon);
  remnant_nucleus->SetMomentum(p4remnant);
}

References genie::GHepParticle::A(), genie::PDGLibrary::Find(), fNuclModel, genie::PDGLibrary::Instance(), LOG, genie::GHepParticle::Pdg(), pINFO, genie::Target::SetHitNucPdg(), and genie::GHepParticle::SetMomentum().

Referenced by ProcessEventRecord().

◆ LoadConfig()

void NucleonDecayPrimaryVtxGenerator::LoadConfig ( void )

private

Definition at line 404 of file NucleonDecayPrimaryVtxGenerator.cxx.

{
//  AlgConfigPool * confp = AlgConfigPool::Instance();
//  const Registry * gc = confp->GlobalParameterList();
 
  fNuclModel = 0;
 
  RgKey nuclkey = "NuclearModel";
  fNuclModel = dynamic_cast<const NuclearModelI *> (this->SubAlg(nuclkey));
  assert(fNuclModel);
}

References fNuclModel, and genie::Algorithm::SubAlg().

Referenced by Configure(), and Configure().

◆ ProcessEventRecord()

void NucleonDecayPrimaryVtxGenerator::ProcessEventRecord ( GHepRecord * event ) const

virtual

Implements genie::EventRecordVisitorI.

Definition at line 52 of file NucleonDecayPrimaryVtxGenerator.cxx.

{
  Interaction * interaction = event->Summary();
  fCurrInitStatePdg = interaction->InitState().Tgt().Pdg();
  fCurrDecayMode = (NucleonDecayMode_t) interaction->ExclTag().DecayMode();
  fCurrDecayedNucleon = interaction->InitState().Tgt().HitNucPdg();
 
  LOG("NucleonDecay", pNOTICE)
    << "Simulating decay " << utils::nucleon_decay::AsString(fCurrDecayMode, fCurrDecayedNucleon)
    << " for an initial state with code: " << fCurrInitStatePdg;
 
  fNucleonIsBound = (pdg::IonPdgCodeToA(fCurrInitStatePdg) > 1);
 
  this->AddInitialState(event);
  this->GenerateDecayedNucleonPosition(event);
  this->GenerateFermiMomentum(event);
  this->GenerateDecayProducts(event);
}