marley::BetaFitNeutrinoSource Class Reference

"Beta-fit" neutrino source More...

#include <NeutrinoSource.hh>

Inheritance diagram for marley::BetaFitNeutrinoSource:

Public Member Functions
	BetaFitNeutrinoSource (int particle_id=marley_utils::ELECTRON_NEUTRINO, double Emin=0., double Emax=50., double Emean=13., double beta=4.5)
virtual double	get_Emax () const override
	Get the maximum neutrino energy (MeV) that can be sampled by this source.
virtual double	get_Emin () const override
	Get the minimum neutrino energy (MeV) that can be sampled by this source.
virtual double	pdf (double E) const override
	Probability density function describing the incident neutrino energy distribution.
Public Member Functions inherited from marley::NeutrinoSource
	NeutrinoSource (int particle_id)
virtual int	get_pid () const
	Get the PDG particle ID for the neutrino type produced by this source.
virtual double	sample_incident_neutrino (int &pdg, marley::Generator &gen) const
	Samples an incident neutrino energy and loads pdg with the PDG code of the appropriate neutrino type.

Protected Attributes
double	alpha_
	pinching parameter (stored as alpha = beta - 1)
double	C_
	dimensionless normalization constant
double	Emax_
double	Emean_
	mean neutrino energy
double	Emin_
	minimum neutrino energy (MeV)
Protected Attributes inherited from marley::NeutrinoSource
int	pid_
	PDG particle ID for the neutrinos produced by this source.

Additional Inherited Members
Static Public Member Functions inherited from marley::NeutrinoSource
static bool	pdg_is_allowed (const int pdg)

Detailed Description

"Beta-fit" neutrino source

Neutrino energies from this source are sampled from a "beta-fit" spectrum (see, for example, equation 7 in Huang, Guo, & Young, Chinese Physics C, 40, 073102 (2016)) with mean neutrino energy \(E_\text{mean}\) and fit parameter \(\beta\). This parameterization is related to the alpha-fit form by \(\alpha = \beta - 1\). The probability density function is given by

\begin{align*}P(E) &= C\left(E/\,E_\text{mean}\right)^{\beta - 1} \exp\left(-\beta\,E/\,E_\text{mean}\right) & \text{E}_\text{min} \leq E \leq \text{E}_\text{max} \end{align*}

where \(C\) is a normalization constant.

Definition at line 204 of file NeutrinoSource.hh.

Constructor & Destructor Documentation

BetaFitNeutrinoSource()

marley::BetaFitNeutrinoSource::BetaFitNeutrinoSource	(	int	particle_id = marley_utils::ELECTRON_NEUTRINO,
		double	Emin = 0.,
		double	Emax = 50.,
		double	Emean = 13.,
		double	beta = 4.5 )

Parameters

particle_id	PDG particle ID for the neutrinos produced by this source
Emin	minimum allowed neutrino energy (MeV)
Emax	maximum allowed neutrino energy (MeV)
Emean	mean neutrino energy (MeV)
beta	dimensionless fit parameter

Definition at line 119 of file NeutrinoSource.cc.

  : NeutrinoSource(particle_id), Emin_(Emin), Emax_(Emax), Emean_(Emean),
  alpha_(beta - 1.), C_(1.)
{
  if ( beta <= 0. ) {
    throw marley::Error("For a \"beta-fit\" neutrino source, a value of"
      " the fit parameter beta <= 0 prevents normalization of the"
      " energy distribution. Please choose a positive value and try again.");
  }
 
  if ( alpha_ < 0. && Emin_ == 0. ) {
    MARLEY_LOG(WARN, "init.config.source") << "For a beta-fit source with"
      " beta < 1 (i.e., alpha < 0) and Emin = 0, the PDF diverges at E = 0.";
  }
 
  // Normalize the source spectrum (not strictly necessary, but having the
  // spectrum approximately normalized makes the default rejection sampling
  // tolerance of 1e-8 reliable for finding the maximum of the spectrum)
  double integral = marley_utils::num_integrate(
    [this](double E) -> double { return this->pdf(E); }, Emin_, Emax_);
 
  // Update the normalization constant, thereby normalizing this object's
  // pdf in the process.
  C_ /= integral;
}

References marley::NeutrinoSource::NeutrinoSource(), alpha_, C_, Emax_, Emean_, Emin_, and pdf().

Member Function Documentation

get_Emax()

double marley::BetaFitNeutrinoSource::get_Emax ( ) const

inlineoverridevirtual

Get the maximum neutrino energy (MeV) that can be sampled by this source.

Implements marley::NeutrinoSource.

Definition at line 349 of file NeutrinoSource.hh.

{ return Emax_; }

References Emax_.

get_Emin()

double marley::BetaFitNeutrinoSource::get_Emin ( ) const

inlineoverridevirtual

Get the minimum neutrino energy (MeV) that can be sampled by this source.

Implements marley::NeutrinoSource.

Definition at line 350 of file NeutrinoSource.hh.

{ return Emin_; }

References Emin_.

pdf()

double marley::BetaFitNeutrinoSource::pdf ( double E ) const

overridevirtual

Probability density function describing the incident neutrino energy distribution.

The neutrino spectrum produced by this source will be folded with the relevant cross sections by a Generator object during event creation

Parameters

E	neutrino energy (MeV)

Returns

Probability density (MeV ^-1)

Implements marley::NeutrinoSource.

Definition at line 146 of file NeutrinoSource.cc.

                                                      {
  return C_ * gamma_pdf_unnorm(E, Emean_, alpha_, Emin_, Emax_);
}

References alpha_, C_, Emax_, Emean_, and Emin_.

Referenced by BetaFitNeutrinoSource().

Member Data Documentation

alpha_

double marley::BetaFitNeutrinoSource::alpha_

protected

pinching parameter (stored as alpha = beta - 1)

Definition at line 229 of file NeutrinoSource.hh.

Referenced by BetaFitNeutrinoSource(), and pdf().

C_

double marley::BetaFitNeutrinoSource::C_

protected

dimensionless normalization constant

Definition at line 230 of file NeutrinoSource.hh.

Referenced by BetaFitNeutrinoSource(), and pdf().

Emax_

double marley::BetaFitNeutrinoSource::Emax_

protected

maximum neutrino energy (MeV)

Definition at line 223 of file NeutrinoSource.hh.

Referenced by BetaFitNeutrinoSource(), get_Emax(), and pdf().

Emean_

double marley::BetaFitNeutrinoSource::Emean_

protected

mean neutrino energy

Note

This is exactly the mean neutrino energy only if \(E_\text{min} = 0 \) and \( Emax = \infty \). Truncating the distribution may alter the mean value appreciably.

Definition at line 228 of file NeutrinoSource.hh.

Referenced by BetaFitNeutrinoSource(), and pdf().

Emin_

double marley::BetaFitNeutrinoSource::Emin_

protected

minimum neutrino energy (MeV)

Definition at line 222 of file NeutrinoSource.hh.

Referenced by BetaFitNeutrinoSource(), get_Emin(), and pdf().

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

• /home/sjg/Desktop/marley/include/marley/NeutrinoSource.hh
• /home/sjg/Desktop/marley/src/NeutrinoSource.cc