genie::flux::GAstroFlux Class Reference

A base class for the concrete astrophysical neutrino flux drivers. More...

#include <GAstroFlux.h>

Inheritance diagram for genie::flux::GAstroFlux:

Classes
class	NuGenerator
class	NuPropagator

Public Member Functions
virtual	~GAstroFlux ()
virtual const PDGCodeList &	FluxParticles (void)
	declare list of flux neutrinos that can be generated (for init. purposes) More...
virtual double	MaxEnergy (void)
	declare the max flux neutrino energy that can be generated (for init. purposes) More...
virtual bool	GenerateNext (void)
	generate the next flux neutrino (return false in err) More...
virtual int	PdgCode (void)
	returns the flux neutrino pdg code More...
virtual double	Weight (void)
	returns the flux neutrino weight (if any) More...
virtual const TLorentzVector &	Momentum (void)
	returns the flux neutrino 4-momentum More...
virtual const TLorentzVector &	Position (void)
	returns the flux neutrino 4-position (note: expect SI rather than physical units) More...
virtual bool	End (void)
	true if no more flux nu's can be thrown (eg reaching end of beam sim ntuples) More...
virtual long int	Index (void)
	returns corresponding index for current flux neutrino (e.g. for a flux ntuple returns the current entry number) More...
virtual void	Clear (Option_t *opt)
	reset state variables based on opt More...
virtual void	GenerateWeighted (bool gen_weighted)
	set whether to generate weighted or unweighted neutrinos More...
void	ForceMinEnergy (double emin)
void	ForceMaxEnergy (double emax)
void	SetDetectorPosition (double latitude, double longitude, double depth, double size)
void	SetRelNuPopulations (double nnue=1, double nnumu=2, double nnutau=0, double nnuebar=1, double nnumubar=2, double nnutaubar=0)
void	SetEnergyPowLawIdx (double n)
void	SetUserCoordSystem (TRotation &rotation)
	rotation Topocentric Horizontal -> User-defined Topocentric Coord System More...
Public Member Functions inherited from genie::GFluxI
virtual	~GFluxI ()

Protected Member Functions
	GAstroFlux ()
void	Initialize (void)
void	CleanUp (void)
void	ResetSelection (void)
Protected Member Functions inherited from genie::GFluxI
	GFluxI ()

Protected Attributes
PDGCodeList *	fPdgCList
	declared list of neutrino pdg-codes that can be thrown by current instance More...
int	fgPdgC
	(current) generated nu pdg-code More...
TLorentzVector	fgP4
	(current) generated nu 4-momentum More...
TLorentzVector	fgX4
	(current) generated nu 4-position More...
double	fgWeight
	(current) generated nu weight More...
double	fMaxEvCut
	(config) user-defined maximum energy cut More...
double	fMinEvCut
	(config) user-defined minimum energy cut More...
bool	fGenWeighted
	(config) generate a weighted or unweighted flux? More...
double	fDetGeoLatitude
	(config) detector: geographic latitude More...
double	fDetGeoLongitude
	(config) detector: geographic longitude More...
double	fDetGeoDepth
	(config) detector: depth from surface More...
double	fDetSize
	(config) detector: size (detector should be enclosed in sphere of this radius) More...
map< int, double >	fRelNuPopulations
	(config) relative neutrino populations More...
TRotation	fRotGEF2THz
	(config) coord. system rotation: GEF translated to detector centre -> THZ More...
TRotation	fRotTHz2User
	(config) coord. system rotation: THZ -> Topocentric user-defined More...
TVector3	fDetCenter
TH1D *	fEnergySpectrum
TH2D *	fSolidAngleAcceptance
NuGenerator *	fNuGen
NuPropagator *	fNuPropg

Detailed Description

A base class for the concrete astrophysical neutrino flux drivers.

<<<< NOTE: CODE UNDER DEVELOPMENT >>>>

COORDINATE SYSTEMS / NEUTRINO GENERATION & PROPAGATION :

Neutrinos are generated on a sphere with radius R_{earth}. Especially,

• For diffuse fluxes: Neutrinos can be generated anywhere on that surface.
• For point sources: Neutrinos are generated at fixed right ascension and declination. Then time is randomized, to account for Earth's rotation, and the Equatorial Coordinates are converted to GEF. So, neutrinos from each point source are generated on circles parallel to the Earth's Equator.

Initially, neutrino coordinates are generated in the Geocentric Earth- Fixed (GEF) Coordinate System (later to be converted to the appropriate detector coordinate system - See further below).

Definition: Geocentric Earth-Fixed (GEF) Coordinate System +z: Points to North Pole. xy: Equatorial plane. +x: Points to the Prime Meridian. +y: As needed to make a right-handed coordinate system.

Neutrinos are then propagated towards the detector. The Earth opaqueness to ultra high energy neutrinos is taken into account. The Earth density profile is modelled using the PREM (Preliminary Earth Model, The Encyclopedia of Solid Earth Geophysics, David E. James, ed., Van Nostrand Reinhold, New York, 1989, p.331).

The detector position is determined in the Spherical/Geographic System by its geographic latitude (angle relative to Equator), its geographic longitude (angle relative to Prime Meridian) and its depth from the surface.

The generated flux neutrinos, propagated through the Earth towards the detector) are then positioned on the surface of a sphere with radius Rd which should fully enclose the neutrino detector. The centre of that sphere is taken to be the origin of the detector coordinate system. The transverse coords are appropriately randomized so that neutrinos from any given direction bath the entire sphere enclosing the detector.

The final flux neutrino coordinates are given in the detector coordinate system. The default detector coordinate system is the Topocentric Horizontal (THZ) Coordinate System. Alternative user-defined topocentric systems can be defined by specifying the appropriate rotation from THZ.

Definition: Topocentric Horizontal (THZ) Coordinate System (default detector coordinate system) +z: Points towards the local zenith. +x: On same plane as local meridian, pointing south. +y: As needed to make a right-handed coordinate system. origin: detector centre

WEIGHTING SCHEMES:

For a detector with geometrical cross section ~ 1km^2, the solid angle acceptance changes by ~10 orders of magnitude across the surface of the Earth.

The driver supports both weighted and un-weighted flux generation schemes. However, because of the enormous changes in solid angle acceptance and energy, only the weighted scheme is practical.

PHYSICS:

The relative neutrino population needs to be set by the user using the SetRelNuPopulations() method. If run without arguments, the following relative populations are set: nue:numu:nutau:nuebar:numubar:nutaubar = 1:2:0:1:2:0

The energy spectrum is follows a power law. The user needs to specify the power-law index by calling SetEnergyPowLawIdx().

Author

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

March 27, 2010

Copyright (c) 2003-2020, The GENIE Collaboration For the full text of the license visit http://copyright.genie-mc.org

Definition at line 126 of file GAstroFlux.h.

Constructor & Destructor Documentation

GAstroFlux::~GAstroFlux ( )

virtual

Definition at line 37 of file GAstroFlux.cxx.

{
  this->CleanUp();
}

GAstroFlux::GAstroFlux ( )

protected

Definition at line 32 of file GAstroFlux.cxx.

{
  this->Initialize();
}

Member Function Documentation

void GAstroFlux::CleanUp ( void  )

protected

Definition at line 342 of file GAstroFlux.cxx.

{
  LOG("Flux", pNOTICE) << "Cleaning up...";

  fRelNuPopulations.clear();
  fPdgCList->clear();

  delete fPdgCList;
  if(fEnergySpectrum) delete fEnergySpectrum;
  if(fSolidAngleAcceptance) delete fSolidAngleAcceptance;

  delete fNuGen;
  delete fNuPropg;
}

void GAstroFlux::Clear ( Option_t *  opt )

virtual

reset state variables based on opt

Implements genie::GFluxI.

Definition at line 150 of file GAstroFlux.cxx.

{
// Dummy clear method needed to conform to GFluxI interface
//
  LOG("Flux", pERROR) << "No clear method implemented for option:"<< opt;
}

virtual bool genie::flux::GAstroFlux::End ( void  )

inlinevirtual

true if no more flux nu's can be thrown (eg reaching end of beam sim ntuples)

Implements genie::GFluxI.

Definition at line 141 of file GAstroFlux.h.

{ return false;      }

virtual const PDGCodeList& genie::flux::GAstroFlux::FluxParticles ( void  )

inlinevirtual

declare list of flux neutrinos that can be generated (for init. purposes)

Implements genie::GFluxI.

Definition at line 134 of file GAstroFlux.h.

{ return *fPdgCList; }

void GAstroFlux::ForceMaxEnergy

(

double

emax

)

Definition at line 144 of file GAstroFlux.cxx.

{
  emax = TMath::Max(0., emax/units::GeV);
  fMaxEvCut = emax;
}

void GAstroFlux::ForceMinEnergy

(

double

emin

)

Definition at line 138 of file GAstroFlux.cxx.

{
  emin = TMath::Max(0., emin/units::GeV);
  fMinEvCut = emin;
}

bool GAstroFlux::GenerateNext ( void  )

virtual

generate the next flux neutrino (return false in err)

Implements genie::GFluxI.

Reimplemented in genie::flux::GPointSourceAstroFlux.

Definition at line 47 of file GAstroFlux.cxx.

{
  // Reset previously generated neutrino code / 4-p / 4-x
  this->ResetSelection();

  if(!fEnergySpectrum) {
    return false;
  }
  if(!fSolidAngleAcceptance) {
    return false;
  }
  if(fRelNuPopulations.size() == 0) {
    return false;
  }

  //
  // Generate neutrino energy & starting position at the Geocentric
  // coordinate system
  //

  double log10Emin = TMath::Log10(TMath::Max(kAstroDefMinEv,fMinEvCut));
  double log10Emax = TMath::Log10(TMath::Min(kAstroDefMaxEv,fMaxEvCut));

  double wght_species = 1.;
  double wght_energy  = 1.;
  double wght_origin  = 1.;

  int    nupdg     = 0;
  double log10E    = -99999;
  double phi       = -999999;
  double costheta  = -999999;

  bool status = true;

  status = fNuGen->SelectNuPdg(
     fGenWeighted, fRelNuPopulations, nupdg, wght_species);
  if(!status) {
     return false;
  }

  status = fNuGen->SelectEnergy(
     fGenWeighted, *fEnergySpectrum, log10Emin, log10Emax, log10E, wght_energy);
  if(!status) {
     return false;
  }
  double Ev = TMath::Power(10.,log10E);

  status = fNuGen->SelectOrigin(
    fGenWeighted, *fSolidAngleAcceptance, phi, costheta, wght_origin);
  if(!status) {
     return false;
  }

  //
  // Propagate through the Earth: Get position, 4-momentum and neutrino
  // pdg code at the boundary of the detector volume
  //

  status = fNuPropg->Go(phi, costheta, fDetCenter, fDetSize, nupdg, Ev);
  if(!status) {
     return false;
  }

  int        pnupdg = fNuPropg->NuPdgAtDetVolBoundary();
  TVector3 & px3    = fNuPropg->X3AtDetVolBoundary();
  TVector3 & pp3    = fNuPropg->P3AtDetVolBoundary();

  //
  // Rotate vectors:

  // GEF translated to detector centre -> THZ
  px3 = fRotGEF2THz * px3;
  pp3 = fRotGEF2THz * pp3;

  // THZ -> Topocentric user-defined detetor system
  px3 = fRotTHz2User * px3;
  pp3 = fRotTHz2User * pp3;

  //
  // Set position, momentum, pdg code and weight variables reported back
  //
  fgWeight = wght_species * wght_energy * wght_origin;
  fgPdgC   = pnupdg;
  fgX4.SetVect(px3*(units::m/units::km));
  fgX4.SetT(0.);
  fgP4.SetVect(pp3);
  fgP4.SetE(pp3.Mag());

  return true;
}

void GAstroFlux::GenerateWeighted ( bool  gen_weighted )

virtual

set whether to generate weighted or unweighted neutrinos

Implements genie::GFluxI.

Definition at line 157 of file GAstroFlux.cxx.

{
  fGenWeighted = gen_weighted;
}

virtual long int genie::flux::GAstroFlux::Index ( void  )

inlinevirtual

returns corresponding index for current flux neutrino (e.g. for a flux ntuple returns the current entry number)

Implements genie::GFluxI.

Definition at line 142 of file GAstroFlux.h.

{ return -1;         }

void GAstroFlux::Initialize ( void  )

protected

Definition at line 286 of file GAstroFlux.cxx.

{
  LOG("Flux", pNOTICE) << "Initializing flux driver";

  bool allow_dup = false;
  fPdgCList = new PDGCodeList(allow_dup);

  // Default: No min/max energy cut
  this->ForceMinEnergy(kAstroDefMinEv);
  this->ForceMaxEnergy(kAstroDefMaxEv);

  // Generate weighted or un-weighted flux?
  fGenWeighted = true;

  // Detector position & size
  fDetGeoLatitude  = -1.;
  fDetGeoLongitude = -1.;
  fDetGeoDepth     = -1.;
  fDetSize         = -1.;
  fDetCenter.SetXYZ(0,0,0); // in the geocentric coord system

  // Normalized 2-D histogram (phi,costheta): detector solid angle
  // as seen from different positions across the face of the Earth
  fSolidAngleAcceptance = 0;

  // Neutrino energy spectrum
  // To be set via SetEnergyPowLawIdx()
  // Can be trivially modified to accomodate different spectra
  fEnergySpectrum = 0;

  // Relative neutrino populations
  // To be set via SetRelNuPopulations()
  // Default nue:numu:nutau:nuebar:numubar:nutaubar = 1:2:0:1:2:0
  fRelNuPopulations.clear();

  // Rotations
  fRotGEF2THz.SetToIdentity();
  fRotTHz2User.SetToIdentity();

  // Utility objects for generating and propagating neutrinos
  fNuGen   = new NuGenerator();
  fNuPropg = new NuPropagator(1.0*units::km);

  // Reset `current' selected flux neutrino
  this->ResetSelection();
}

double GAstroFlux::MaxEnergy ( void  )

virtual

declare the max flux neutrino energy that can be generated (for init. purposes)

Implements genie::GFluxI.

Definition at line 42 of file GAstroFlux.cxx.

{
  return TMath::Min(kAstroDefMaxEv, fMaxEvCut);
}

virtual const TLorentzVector& genie::flux::GAstroFlux::Momentum ( void  )

inlinevirtual

returns the flux neutrino 4-momentum

Implements genie::GFluxI.

Definition at line 139 of file GAstroFlux.h.

{ return fgP4;       }

virtual int genie::flux::GAstroFlux::PdgCode ( void  )

inlinevirtual

returns the flux neutrino pdg code

Implements genie::GFluxI.

Definition at line 137 of file GAstroFlux.h.

{ return fgPdgC;     }

virtual const TLorentzVector& genie::flux::GAstroFlux::Position ( void  )

inlinevirtual

returns the flux neutrino 4-position (note: expect SI rather than physical units)

Implements genie::GFluxI.

Definition at line 140 of file GAstroFlux.h.

{ return fgX4;       }

void GAstroFlux::ResetSelection ( void  )

protected

Definition at line 333 of file GAstroFlux.cxx.

{
// initializing running neutrino pdg-code, 4-position, 4-momentum

  fgPdgC = 0;
  fgP4.SetPxPyPzE (0.,0.,0.,0.);
  fgX4.SetXYZT    (0.,0.,0.,0.);
}

void GAstroFlux::SetDetectorPosition	(	double	latitude,
		double	longitude,
		double	depth,
		double	size
	)

Definition at line 162 of file GAstroFlux.cxx.

{
  depth = TMath::Max(0., depth/units::km);
  size  = TMath::Max(0., size /units::km);

  assert(latitude  >= -kPi/2. && latitude  <= kPi/2.);
  assert(longitude >= 0.      && longitude < 2.*kPi );

  // set inputs
  fDetGeoLatitude   = latitude;
  fDetGeoLongitude  = longitude;
  fDetGeoDepth      = depth;
  fDetSize          = size;

  //
  // Compute detector/topocentric coordinate system center in the
  // geocentric coordinate system.
  //

  double REarth = constants::kREarth/units::km;
  double radius = REarth - fDetGeoDepth;

  double theta = kPi/2. - fDetGeoLatitude;
  double phi   = fDetGeoLongitude;

  double sintheta = TMath::Sin(theta);
  double costheta = TMath::Cos(theta);
  double sinphi   = TMath::Sin(phi);
  double cosphi   = TMath::Cos(phi);

  double xdc = radius * sintheta * cosphi;
  double ydc = radius * sintheta * sinphi;
  double zdc = radius * costheta;

  fDetCenter.SetXYZ(xdc,ydc,zdc);

  //
  // Coordinate System Rotation:
  // GEF translated to detector centre -> THZ
  //
  // ...
  // ... TODO
  // ...
}

void GAstroFlux::SetEnergyPowLawIdx

(

double

n

)

Definition at line 258 of file GAstroFlux.cxx.

{
  if(fEnergySpectrum) delete fEnergySpectrum;

  double log10Emin = TMath::Log10(kAstroDefMinEv);
  double log10Emax = TMath::Log10(kAstroDefMaxEv);

  fEnergySpectrum =
    new TH1D("fEnergySpectrum","",kAstroNlog10EvBins,log10Emin,log10Emax);
  fEnergySpectrum->SetDirectory(0);

  for(int i=1; i<=kAstroNlog10EvBins; i++) {
    double log10E = fEnergySpectrum->GetBinCenter(i);
    double Ev     = TMath::Power(10., log10E);
    double flux   = TMath::Power(Ev, -1*n);
    fEnergySpectrum->SetBinContent(i,flux);
  }

  // normalize
  double max = fEnergySpectrum->GetMaximum();
  fEnergySpectrum->Scale(1./max);
}

void GAstroFlux::SetRelNuPopulations	(	double	nnue = 1,
		double	nnumu = 2,
		double	nnutau = 0,
		double	nnuebar = 1,
		double	nnumubar = 2,
		double	nnutaubar = 0
	)

Definition at line 208 of file GAstroFlux.cxx.

{
  fRelNuPopulations.clear();
  fPdgCList->clear();

  if(nnue>0.) {
    fRelNuPopulations.insert(
       map<int,double>::value_type(kPdgNuE, nnue));
    fPdgCList->push_back(kPdgNuE);
  }
  if(nnumu>0.) {
    fRelNuPopulations.insert(
       map<int,double>::value_type(kPdgNuMu, nnumu));
    fPdgCList->push_back(kPdgNuMu);
  }
  if(nnutau>0.) {
    fRelNuPopulations.insert(
       map<int,double>::value_type(kPdgNuTau, nnutau));
    fPdgCList->push_back(kPdgNuTau);
  }
  if(nnuebar>0.) {
    fRelNuPopulations.insert(
       map<int,double>::value_type(kPdgAntiNuE, nnuebar));
    fPdgCList->push_back(kPdgAntiNuE);
  }
  if(nnumubar>0.) {
    fRelNuPopulations.insert(
       map<int,double>::value_type(kPdgAntiNuMu, nnumubar));
    fPdgCList->push_back(kPdgAntiNuMu);
  }
  if(nnutaubar>0.) {
    fRelNuPopulations.insert(
       map<int,double>::value_type(kPdgAntiNuTau, nnutaubar));
    fPdgCList->push_back(kPdgAntiNuTau);
  }

  double tot = nnue + nnumu + nnutau + nnuebar + nnumubar + nnutaubar;
  assert(tot>0.);

  // normalize to 1.
  map<int,double>::iterator iter = fRelNuPopulations.begin();
  for ( ; iter != fRelNuPopulations.end(); ++iter) {
    double fraction = iter->second;
    double norm_fraction = fraction/tot;
    fRelNuPopulations[iter->first] = norm_fraction;
  }
}

void GAstroFlux::SetUserCoordSystem

(

TRotation &

rotation

)

rotation Topocentric Horizontal -> User-defined Topocentric Coord System

Definition at line 281 of file GAstroFlux.cxx.

{
  fRotTHz2User = rotation;
}

virtual double genie::flux::GAstroFlux::Weight ( void  )

inlinevirtual

returns the flux neutrino weight (if any)

Implements genie::GFluxI.

Definition at line 138 of file GAstroFlux.h.

{ return fgWeight;   }

Member Data Documentation

TVector3 genie::flux::GAstroFlux::fDetCenter

protected

Definition at line 190 of file GAstroFlux.h.

double genie::flux::GAstroFlux::fDetGeoDepth

protected

(config) detector: depth from surface

Definition at line 184 of file GAstroFlux.h.

double genie::flux::GAstroFlux::fDetGeoLatitude

protected

(config) detector: geographic latitude

Definition at line 182 of file GAstroFlux.h.

double genie::flux::GAstroFlux::fDetGeoLongitude

protected

(config) detector: geographic longitude

Definition at line 183 of file GAstroFlux.h.

double genie::flux::GAstroFlux::fDetSize

protected

(config) detector: size (detector should be enclosed in sphere of this radius)

Definition at line 185 of file GAstroFlux.h.

TH1D* genie::flux::GAstroFlux::fEnergySpectrum

protected

Definition at line 191 of file GAstroFlux.h.

bool genie::flux::GAstroFlux::fGenWeighted

protected

(config) generate a weighted or unweighted flux?

Definition at line 181 of file GAstroFlux.h.

TLorentzVector genie::flux::GAstroFlux::fgP4

protected

(current) generated nu 4-momentum

Definition at line 175 of file GAstroFlux.h.

int genie::flux::GAstroFlux::fgPdgC

protected

(current) generated nu pdg-code

Definition at line 174 of file GAstroFlux.h.

double genie::flux::GAstroFlux::fgWeight

protected

(current) generated nu weight

Definition at line 177 of file GAstroFlux.h.

TLorentzVector genie::flux::GAstroFlux::fgX4

protected

(current) generated nu 4-position

Definition at line 176 of file GAstroFlux.h.

double genie::flux::GAstroFlux::fMaxEvCut

protected

(config) user-defined maximum energy cut

Definition at line 179 of file GAstroFlux.h.

double genie::flux::GAstroFlux::fMinEvCut

protected

(config) user-defined minimum energy cut

Definition at line 180 of file GAstroFlux.h.

NuGenerator* genie::flux::GAstroFlux::fNuGen

protected

Definition at line 193 of file GAstroFlux.h.

NuPropagator* genie::flux::GAstroFlux::fNuPropg

protected

Definition at line 194 of file GAstroFlux.h.

PDGCodeList* genie::flux::GAstroFlux::fPdgCList

protected

declared list of neutrino pdg-codes that can be thrown by current instance

Definition at line 173 of file GAstroFlux.h.

map<int,double> genie::flux::GAstroFlux::fRelNuPopulations

protected

(config) relative neutrino populations

Definition at line 186 of file GAstroFlux.h.

TRotation genie::flux::GAstroFlux::fRotGEF2THz

protected

(config) coord. system rotation: GEF translated to detector centre -> THZ

Definition at line 187 of file GAstroFlux.h.

TRotation genie::flux::GAstroFlux::fRotTHz2User

protected

(config) coord. system rotation: THZ -> Topocentric user-defined

Definition at line 188 of file GAstroFlux.h.

TH2D* genie::flux::GAstroFlux::fSolidAngleAcceptance

protected

Definition at line 192 of file GAstroFlux.h.

---

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

• Generator/src/Tools/Flux/GAstroFlux.h
• Generator/src/Tools/Flux/GAstroFlux.cxx