Abstract base class for compound nucleus de-excitation channels. More...

#include <ExitChannel.hh>

Inheritance diagram for marley::ExitChannel:

Public Member Functions
	ExitChannel ()=default

	ExitChannel (int pdgi, int qi, double Exi, int twoJi, marley::Parity Pi, double rho_i, marley::StructureDatabase &sdb)

virtual void	do_decay (double &Exf, int &two_Jf, marley::Parity &Pf, const std::shared_ptr< HepMC3::GenParticle > &compound_nucleus, std::shared_ptr< HepMC3::GenParticle > &emitted_particle, std::shared_ptr< HepMC3::GenParticle > &residual_nucleus, int &qIon, marley::Generator &gen) const =0
	Simulates a nuclear decay into this channel.

virtual bool	emits_fragment () const =0
	Returns true if this channel involves fragment emission or false if it involves gamma-ray emission.

virtual int	emitted_particle_pdg () const =0
	Returns the PDG code for the particle (gamma-ray or nuclear fragment) emitted by decays into this ExitChannel.

virtual int	final_nucleus_pdg () const =0
	Returns the PDG code for the final nucleus.

virtual bool	is_continuum () const =0
	Returns true if this channel accesses the particle-unbound continuum of nuclear levels or false otherwise.

double	width () const
	Get the total decay width into this channel (MeV)

Static Public Member Functions
template<typename It>
static marley::IteratorToPointerMember< It, double >	make_width_iterator (It it)
	Convert an iterator that points to an ExitChannel object into an iterator to the ExitChannel's width_ member variable.

Protected Member Functions
virtual void	compute_total_width ()=0

virtual void	prepare_products (const std::shared_ptr< HepMC3::GenParticle > &compound_nucleus, std::shared_ptr< HepMC3::GenParticle > &emitted_particle, std::shared_ptr< HepMC3::GenParticle > &residual_nucleus, double Exf, int &qf, marley::Generator &gen) const
	Helper function that prepares Particle objects representing the products of the two-body decay.

Protected Attributes
double	Exi_
	Initial nuclear excitation energy \( E_x \) (MeV)

double	one_over_two_pi_rho_i_

int	pdgi_
	PDG code for the initial nucleus.

marley::Parity	Pi_
	Initial nuclear parity \( \Pi \).

int	qi_

marley::StructureDatabase *	sdb_
	StructureDatabase to use in calculations.

int	twoJi_
	Two times the initial nuclear spin \( J \).

double	width_
	Total decay width into this channel (MeV)

Detailed Description

Abstract base class for compound nucleus de-excitation channels.

Definition at line 36 of file ExitChannel.hh.

Constructor & Destructor Documentation

◆ ExitChannel() [1/2]

marley::ExitChannel::ExitChannel ( )

default

Note: This line keeps old versions (4.9.3) of GCC happy

◆ ExitChannel() [2/2]

marley::ExitChannel::ExitChannel	(	int	pdgi,
		int	qi,
		double	Exi,
		int	twoJi,
		marley::Parity	Pi,
		double	rho_i,
		marley::StructureDatabase &	sdb )

inline

Parameters

pdgi	PDG code for the initial nucleus
qi	Net charge (in units of the elementary charge) of the initial atom or ion
Exi	Initial nuclear excitation energy \( E_x \) (MeV)
twoJi	Two times the initial nuclear spin \( J \)
Pi	Initial nuclear parity \( \Pi \)
rho_i	Initial nuclear level density \( \rho(E_x, J, \Pi) \) in the vicinity of the initial level (MeV^-1). This value will be used to compute an overall normalization factor for decay widths in this exit channel.
sdb	Reference to the StructureDatabase that will be used in decay width calculations by this ExitChannel object

Definition at line 55 of file ExitChannel.hh.

                                                     : pdgi_( pdgi ),
        qi_( qi ), Exi_( Exi ), twoJi_( twoJi ), Pi_( Pi ), sdb_( &sdb )
      {
        one_over_two_pi_rho_i_ = std::pow( 2. * marley_utils::pi * rho_i, -1 );
      }

References Exi_, one_over_two_pi_rho_i_, pdgi_, Pi_, qi_, sdb_, and twoJi_.

Member Function Documentation

◆ compute_total_width()

virtual void marley::ExitChannel::compute_total_width ( )

protectedpure virtual

Helper function that initializes the width_ member variable upon construction

Implemented in marley::ContinuumExitChannel, marley::FragmentDiscreteExitChannel, and marley::GammaDiscreteExitChannel.

◆ do_decay()

virtual void marley::ExitChannel::do_decay	(	double &	Exf,
		int &	two_Jf,
		marley::Parity &	Pf,
		const std::shared_ptr< HepMC3::GenParticle > &	compound_nucleus,
		std::shared_ptr< HepMC3::GenParticle > &	emitted_particle,
		std::shared_ptr< HepMC3::GenParticle > &	residual_nucleus,
		int &	qIon,
		marley::Generator &	gen ) const

pure virtual

Simulates a nuclear decay into this channel.

Parameters

[out]	Exf	The final nuclear excitation energy
[out]	two_Jf	Two times the final nuclear spin
[out]	Pf	The final nuclear parity
[in]	compound_nucleus	Particle object representing the initial nucleus
[out]	emitted_particle	Particle emitted in the de-excitation
[out]	residual_nucleus	Final-state nucleus after particle emission
[out]	qIon	Charge (in units of the elementary charge) of the final-state nucleus (ion) after particle emission
	gen	Generator to use for random sampling

Implemented in marley::ContinuumExitChannel, and marley::DiscreteExitChannel.

◆ emits_fragment()

virtual bool marley::ExitChannel::emits_fragment ( ) const

pure virtual

Returns true if this channel involves fragment emission or false if it involves gamma-ray emission.

Implemented in marley::FragmentExitChannel, and marley::GammaExitChannel.

◆ emitted_particle_pdg()

virtual int marley::ExitChannel::emitted_particle_pdg ( ) const

pure virtual

Returns the PDG code for the particle (gamma-ray or nuclear fragment) emitted by decays into this ExitChannel.

Implemented in marley::FragmentExitChannel, and marley::GammaExitChannel.

Referenced by prepare_products().

◆ final_nucleus_pdg()

virtual int marley::ExitChannel::final_nucleus_pdg ( ) const

pure virtual

Returns the PDG code for the final nucleus.

Implemented in marley::FragmentExitChannel, and marley::GammaExitChannel.

Referenced by prepare_products().

◆ is_continuum()

virtual bool marley::ExitChannel::is_continuum ( ) const

pure virtual

Returns true if this channel accesses the particle-unbound continuum of nuclear levels or false otherwise.

Implemented in marley::ContinuumExitChannel, and marley::DiscreteExitChannel.

Referenced by marley::NucleusDecayer::process_event(), and marley::OMPWeightCalculator::weight().

◆ make_width_iterator()

template<typename It>

static marley::IteratorToPointerMember< It, double > marley::ExitChannel::make_width_iterator ( It it )

inlinestatic

Convert an iterator that points to an ExitChannel object into an iterator to the ExitChannel's width_ member variable.

This is used to load a std::discrete_distribution with decay widths for sampling without redundant storage.

Definition at line 96 of file ExitChannel.hh.

      {
        return marley::IteratorToPointerMember< It,
          double >( it, &marley::ExitChannel::width_ );
      }

References width_.

Referenced by marley::HauserFeshbachDecay::sample_exit_channel().

◆ prepare_products()

void marley::ExitChannel::prepare_products	(	const std::shared_ptr< HepMC3::GenParticle > &	compound_nucleus,
		std::shared_ptr< HepMC3::GenParticle > &	emitted_particle,
		std::shared_ptr< HepMC3::GenParticle > &	residual_nucleus,
		double	Exf,
		int &	qf,
		marley::Generator &	gen ) const

protectedvirtual

Helper function that prepares Particle objects representing the products of the two-body decay.

Parameters

[out]	compound_nucleus	Particle object representing the initial nucleus
[out]	emitted_particle	Particle emitted in the binary decay
[out]	residual_nucleus	Particle representing the daughter nucleus
[in]	Exf	Excitation energy of the daughter nucleus
[out]	qf	Final ion charge after particle emission
	gen	Generator to use for random sampling

Definition at line 405 of file ExitChannel.cc.

{
  const auto& mt = marley::MassTable::Instance();
  int ep_pdg = this->emitted_particle_pdg();
  double ep_mass = mt.get_particle_mass( ep_pdg );
 
  emitted_particle = marley_hepmc3::make_particle( ep_pdg,
    marley_hepmc3::NUHEPMC_FINAL_STATE_STATUS, ep_mass );
 
  // Proton number of the emitted particle
  int ep_Z = marley_utils::get_particle_Z( ep_pdg );
 
  // Final ion charge after particle emission
  qf = qi_ - ep_Z;
 
  double me = mt.get_particle_mass( marley_utils::ELECTRON );
  int remnant_pdg = this->final_nucleus_pdg();
 
  // Approximate the ground state mass of the ion formed when the fragment is
  // emitted by subtracting qf electron masses from the atomic mass for the
  // final nuclide.
  double Mfgs_ion = mt.get_atomic_mass( remnant_pdg ) - qf*me;
 
  residual_nucleus = marley_hepmc3::make_particle( remnant_pdg,
    marley_hepmc3::NUHEPMC_INTERMEDIATE_RESIDUE_STATUS, Mfgs_ion + Exf );
 
  // Now that the PDG codes, masses, and net charges of the binary decay
  // products have been set, choose a direction for the emitted particle.
  // TODO: Consider changing this to a more realistic model instead of
  // isotropic emissions.
  double cos_theta_emitted_particle
    = gen.uniform_random_double( -1., 1., true );
  double phi_emitted_particle
    = gen.uniform_random_double( 0., marley_utils::two_pi, false );
 
  // Handle the kinematics calculations for this decay. Load the
  // final-state particle objects with their full 4-momenta.
  marley_kinematics::two_body_decay( compound_nucleus, emitted_particle,
    residual_nucleus, cos_theta_emitted_particle, phi_emitted_particle );
}

References emitted_particle_pdg(), final_nucleus_pdg(), marley::MassTable::Instance(), qi_, and marley::Generator::uniform_random_double().

Referenced by marley::ContinuumExitChannel::do_decay(), and marley::DiscreteExitChannel::do_decay().

◆ width()

double marley::ExitChannel::width ( ) const

inline

Get the total decay width into this channel (MeV)

Definition at line 103 of file ExitChannel.hh.

103{ return width_; }

References width_.

Member Data Documentation

◆ Exi_

double marley::ExitChannel::Exi_

protected

Initial nuclear excitation energy \( E_x \) (MeV)

Definition at line 142 of file ExitChannel.hh.

Referenced by ExitChannel(), marley::GammaDiscreteExitChannel::compute_total_width(), marley::GammaContinuumExitChannel::E_c_max(), and marley::FragmentExitChannel::max_Exf().

◆ one_over_two_pi_rho_i_

double marley::ExitChannel::one_over_two_pi_rho_i_

protected

Normalization factor needed so that the decay widths have correct units

This factor is equal to \( \left[ 2\pi\rho(E_x, J, \Pi) \right]^{-1} \) where \(\rho\) is the initial nuclear level density (MeV^-1) in the vicinity of the initial nuclear level. This level has excitation energy \( E_x \), total spin \( J \), and parity \( \Pi \).

Definition at line 157 of file ExitChannel.hh.

Referenced by ExitChannel(), marley::FragmentDiscreteExitChannel::compute_total_width(), and marley::GammaDiscreteExitChannel::compute_total_width().

◆ pdgi_

int marley::ExitChannel::pdgi_

protected

PDG code for the initial nucleus.

Definition at line 135 of file ExitChannel.hh.

Referenced by ExitChannel(), marley::GammaDiscreteExitChannel::compute_total_width(), marley::FragmentExitChannel::final_nucleus_pdg(), marley::GammaExitChannel::final_nucleus_pdg(), and marley::FragmentExitChannel::max_Exf().

◆ Pi_

marley::Parity marley::ExitChannel::Pi_

protected

Initial nuclear parity \( \Pi \).

Definition at line 148 of file ExitChannel.hh.

Referenced by ExitChannel(), and marley::FragmentDiscreteExitChannel::compute_total_width().

◆ qi_

int marley::ExitChannel::qi_

protected

Net charge (in units of the elementary charge) of the initial atom or ion

Definition at line 139 of file ExitChannel.hh.

Referenced by ExitChannel(), and prepare_products().

◆ sdb_

marley::StructureDatabase* marley::ExitChannel::sdb_

protected

StructureDatabase to use in calculations.

Definition at line 163 of file ExitChannel.hh.

Referenced by ExitChannel(), marley::FragmentDiscreteExitChannel::compute_total_width(), and marley::GammaDiscreteExitChannel::compute_total_width().

◆ twoJi_

int marley::ExitChannel::twoJi_

protected

Two times the initial nuclear spin \( J \).

Definition at line 145 of file ExitChannel.hh.

Referenced by ExitChannel(), marley::FragmentDiscreteExitChannel::compute_total_width(), and marley::GammaDiscreteExitChannel::compute_total_width().

◆ width_

double marley::ExitChannel::width_

protected

Total decay width into this channel (MeV)

Definition at line 160 of file ExitChannel.hh.

Referenced by marley::ContinuumExitChannel::compute_total_width(), marley::FragmentDiscreteExitChannel::compute_total_width(), marley::GammaDiscreteExitChannel::compute_total_width(), make_width_iterator(), and width().

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

/home/sjg/Desktop/marley/include/marley/ExitChannel.hh
/home/sjg/Desktop/marley/src/ExitChannel.cc

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ ExitChannel() [1/2]

◆ ExitChannel() [2/2]

Member Function Documentation

◆ compute_total_width()

◆ do_decay()

◆ emits_fragment()

◆ emitted_particle_pdg()

◆ final_nucleus_pdg()

◆ is_continuum()

◆ make_width_iterator()

◆ prepare_products()

◆ width()

Member Data Documentation

◆ Exi_

◆ one_over_two_pi_rho_i_

◆ pdgi_

◆ Pi_

◆ qi_

◆ sdb_

◆ twoJi_

◆ width_