marley::NuclearReaction Class Reference

A neutrino-nucleus reaction. More...

#include <NuclearReaction.hh>

Inheritance diagram for marley::NuclearReaction:

Public Member Functions
	NuclearReaction (ProcessType pt, int pdg_a, int pdg_b, int pdg_c, int pdg_d, int q_d, const std::string &source_file)
virtual marley::TargetAtom	atomic_target () const override final
	Returns the target atom involved in this reaction.
double	max_level_energy (double KEa) const
	Get the maximum possible excitation energy (MeV) of the final-state residue that is kinematically allowed.
double	threshold_kinetic_energy () const override
	Get the minimum lab-frame kinetic energy (MeV) of the projectile that allows this reaction to proceed via a transition to the residue's ground state.
double	weak_nuclear_charge () const
Public Member Functions inherited from marley::Reaction
	Reaction (const std::string &source_file)
	Construct a Reaction with the resolved path of the data file.
virtual std::shared_ptr< HepMC3::GenEvent >	create_event (int pdg_a, double KEa, marley::Generator &gen) const =0
	Create an event object for this reaction.
const std::string &	get_description () const
	Get a string that contains the formula for this reaction.
int	pdg_a () const
	Get the projectile PDG code.
int	pdg_b () const
	Get the target PDG code.
ProcessType	process_type () const
	Get the process type for this reaction.
const std::string &	source_file () const
	Get the resolved path of the reaction data file used to construct this Reaction.
virtual double	total_xs (int pdg_a, double KEa) const =0
	Compute the reaction's total cross section (MeV -2)

Protected Member Functions
virtual std::shared_ptr< HepMC3::GenEvent >	make_nuclear_event_object (double KEa, const std::shared_ptr< HepMC3::GenParticle > &ejectile, const std::shared_ptr< HepMC3::GenParticle > &residue, double E_level, int twoJ, const marley::Parity &P) const
	Helper function that makes a complete event object for a nuclear reaction.
virtual std::shared_ptr< HepMC3::GenEvent >	make_nuclear_event_object (double KEa, double pc_cm, double cos_theta_c_cm, double phi_c_cm, double Ec_cm, double Ed_cm, double E_level, int twoJ, const marley::Parity &P) const
	Helper function that makes a complete event object for a nuclear reaction.
void	set_charge_attributes (std::shared_ptr< HepMC3::GenEvent > &event) const
	Helper function that sets the charges of the target and residue in an otherwise complete event record.
virtual void	set_description ()
	Creates the description string based on the PDG code values for the initial and final particles.
void	set_nuclear_residue_attributes (const std::shared_ptr< HepMC3::GenParticle > &residue, double E_level, int twoJ, const marley::Parity &P) const
	Helper function that adds the nuclear level attributes ( \( E_x \), \( 2J \), and parity) needed to keep track of the residue's de-excitation state to an otherwise complete event record.
Protected Member Functions inherited from marley::Reaction
virtual std::shared_ptr< HepMC3::GenEvent >	make_event_object (double KEa, const std::shared_ptr< HepMC3::GenParticle > &ejectile, const std::shared_ptr< HepMC3::GenParticle > &residue) const
	Helper function that makes an event object.
virtual std::shared_ptr< HepMC3::GenEvent >	make_event_object (double KEa, double pc_cm, double cos_theta_c_cm, double phi_c_cm, double Ec_cm, double Ed_cm, int residue_status) const
	Helper function that makes an event object.
void	two_two_scatter (double KEa, double &s, double &Ec_cm, double &pc_cm, double &Ed_cm) const
	Helper function that handles CM frame kinematics for the reaction.

Protected Attributes
int	Af_
	Residue mass number.
int	Ai_
	Target mass number.
double	KEa_threshold_
	Lab-frame kinetic energy of the projectile at threshold for this reaction (i.e., the residue is produced in its ground state, and all final-state particles are at rest in the CM frame)
double	md_gs_
	Ground state mass (MeV) of the residue.
int	q_d_
	Net charge of the residue (in units of the proton charge) following this reaction.
int	Zf_
	Residue atomic number.
int	Zi_
	Target atomic number.
Protected Attributes inherited from marley::Reaction
std::string	description_
	String that contains a formula describing the reaction.
double	ma_
	Projectile mass (MeV)
double	mb_
	Target mass (MeV)
double	mc_
	Ejectile mass (MeV)
double	md_
	Residue mass (MeV)
int	pdg_a_
	PDG code for the projectile.
int	pdg_b_
	PDG code for the target.
int	pdg_c_
	PDG code for the ejectile.
int	pdg_d_
	PDG code for the residue.
ProcessType	process_type_
	Type of scattering process (CC, NC) represented by this reaction.
const std::string	source_file_
	Resolved path of the reaction data file.

Additional Inherited Members
Public Types inherited from marley::Reaction
enum	DataFormat { DiscreteStrengths = 0 , MultipoleResponses = 1 }
	Enumerated type describing the file format for reaction data. More...
enum	ProcessType {   Unknown = -1 , NeutrinoCC_Discrete = 0 , AntiNeutrinoCC_Discrete = 1 , NC_Discrete = 2 ,   NuElectronElastic = 3 , NeutrinoCC_Continuum = 4 , AntiNeutrinoCC_Continuum = 5 , NC_Continuum = 6 ,   StandaloneDecay = 7 }
	Enumerated type describing the kind of scattering process represented by a Reaction. More...
Static Public Member Functions inherited from marley::Reaction
static int	get_ejectile_pdg (int pdg_a, ProcessType proc_type)
static void	get_residue_pdg_and_charge (ProcessType proc_type, int pdg_b, int &pdg_d, int &q_d)
static std::vector< std::unique_ptr< Reaction > >	load_from_file (const std::string &filename, StructureDatabase &db, CoulombCorrector::CoulombMode coulomb_mode, const JSON &ff_config)
static std::string	proc_type_to_string (const ProcessType &pt)
Static Protected Member Functions inherited from marley::Reaction
static const std::vector< int > &	get_projectiles (ProcessType proc_type)

Detailed Description

A neutrino-nucleus reaction.

Definition at line 40 of file NuclearReaction.hh.

Constructor & Destructor Documentation

NuclearReaction()

marley::NuclearReaction::NuclearReaction	(	ProcessType	pt,
		int	pdg_a,
		int	pdg_b,
		int	pdg_c,
		int	pdg_d,
		int	q_d,
		const std::string &	source_file )

Parameters

pt	Type of scattering process represented by this Reaction
pdg_a	Projectile PDG code
pdg_b	Target PDG code
pdg_c	Ejectile PDG code
pdg_d	Residue PDG code
q_d	Charge of the residue after the prompt 2->2 scatter represented by this NuclearReaction object

Definition at line 35 of file NuclearReaction.cc.

  : Reaction( source_file ), q_d_( q_d )
{
  // Initialize the process type (NC, neutrino/antineutrino CC)
  process_type_ = pt;
 
  // Initialize the PDG codes for the 2->2 scatter particles
  pdg_a_ = pdg_a;
  pdg_b_ = pdg_b;
  pdg_c_ = pdg_c;
  pdg_d_ = pdg_d;
 
  // Get initial and final values of the nuclear charge and mass number from
  // the PDG codes
  Zi_ = (pdg_b_ % 10000000) / 10000;
  Ai_ = (pdg_b_ % 10000) / 10;
  Zf_ = (pdg_d_ % 10000000) / 10000;
  Af_ = (pdg_d_ % 10000) / 10;
 
  const marley::MassTable& mt = marley::MassTable::Instance();
 
  // Get the particle masses from the mass table
  ma_ = mt.get_particle_mass( pdg_a_ );
  mc_ = mt.get_particle_mass( pdg_c_ );
 
  // If the target (particle b) or residue (particle d)
  // has a particle ID greater than 10^9, assume that it
  // is an atom rather than a bare nucleus
  if ( pdg_b_ > 1000000000 ) mb_ = mt.get_atomic_mass( pdg_b_ );
  else mb_ = mt.get_particle_mass( pdg_b_ );
 
  if ( pdg_d_ > 1000000000 ) {
    // If particle d is an atom and is ionized as a result of this reaction
    // (e.g., q_d_ != 0), then approximate its ground-state ionized mass by
    // subtracting the appropriate number of electron masses from its atomic
    // (i.e., neutral) ground state mass.
    md_gs_ = mt.get_atomic_mass( pdg_d_ )
      - ( q_d_ * mt.get_particle_mass(marley_utils::ELECTRON) );
  }
  else {
    md_gs_ = mt.get_particle_mass( pdg_d_ );
  }
 
  KEa_threshold_ = ( std::pow(mc_ + md_gs_, 2)
    - std::pow(ma_ + mb_, 2) ) / ( 2.*mb_ );
 
  this->set_description();
}

References marley::Reaction::Reaction(), Af_, Ai_, marley::MassTable::get_atomic_mass(), marley::MassTable::get_particle_mass(), marley::MassTable::Instance(), KEa_threshold_, marley::Reaction::ma_, marley::Reaction::mb_, marley::Reaction::mc_, md_gs_, marley::Reaction::pdg_a(), marley::Reaction::pdg_a_, marley::Reaction::pdg_b(), marley::Reaction::pdg_b_, marley::Reaction::pdg_c_, marley::Reaction::pdg_d_, marley::Reaction::process_type_, q_d_, set_description(), marley::Reaction::source_file(), Zf_, and Zi_.

Referenced by marley::DiscreteNuclearReaction::DiscreteNuclearReaction().

Member Function Documentation

atomic_target()

virtual marley::TargetAtom marley::NuclearReaction::atomic_target ( ) const

inlinefinaloverridevirtual

Returns the target atom involved in this reaction.

For nuclear reactions, this is identical to the pdg_b_ member variable. For electron reactions, it is distinct (since particle b is the initial struck electron).

Implements marley::Reaction.

Definition at line 54 of file NuclearReaction.hh.

        { return marley::TargetAtom( pdg_b_ ); }

References marley::Reaction::pdg_b_.

make_nuclear_event_object() [1/2]

std::shared_ptr< HepMC3::GenEvent > marley::NuclearReaction::make_nuclear_event_object ( double KEa, const std::shared_ptr< HepMC3::GenParticle > & ejectile, const std::shared_ptr< HepMC3::GenParticle > & residue, double E_level, int twoJ, const marley::Parity & P ) const

protectedvirtual

Helper function that makes a complete event object for a nuclear reaction.

This function expects pre-made HepMC3::GenParticle objects as input that have four-momenta expressed in the lab frame.

Parameters

KEa	Lab-frame kinetic energy (MeV) of the projectile
ejectile	GenParticle object for the ejectile
residue	GenParticle object for the residue
E_level	Residue excitation energy (MeV)
twoJ	Two times the residue spin
P	Intrinsic parity of the residue

Definition at line 176 of file NuclearReaction.cc.

{
  // Create the event skeleton from the pre-made final-state particles
  auto event = marley::Reaction::make_event_object( KEa, ejectile, residue );
 
  // Attach the charge attributes for the target and residue
  this->set_charge_attributes( event );
 
  // Add the nuclear level attributes needed to keep track of the residue's
  // de-excitation state
  this->set_nuclear_residue_attributes( residue, E_level, twoJ, P );
 
  return event;
}

References marley::Reaction::make_event_object(), set_charge_attributes(), and set_nuclear_residue_attributes().

make_nuclear_event_object() [2/2]

std::shared_ptr< HepMC3::GenEvent > marley::NuclearReaction::make_nuclear_event_object ( double KEa, double pc_cm, double cos_theta_c_cm, double phi_c_cm, double Ec_cm, double Ed_cm, double E_level, int twoJ, const marley::Parity & P ) const

protectedvirtual

Helper function that makes a complete event object for a nuclear reaction.

This function should be called by marley::NuclearReaction::create_event() after CM frame scattering angles have been sampled for the ejectile. In addition to creating the event skeleton (by delegating to marley::Reaction::make_event_object()), it attaches the charge and nuclear level attributes needed to keep track of the residue's de-excitation state.

Parameters

KEa	Lab-frame kinetic energy (MeV) of the projectile
pc_cm	Ejectile 3-momentum magnitude (MeV) in the CM frame
cos_theta_c_cm	Cosine of ejectile's CM frame polar angle
phi_c_cm	Ejectile's CM frame azimuthal angle (radians)
Ec_cm	Ejectile total energy (MeV) in the CM frame
Ed_cm	Residue total energy (MeV) in the CM frame
E_level	Residue excitation energy (MeV)
twoJ	Two times the residue spin
P	Intrinsic parity of the residue

Definition at line 152 of file NuclearReaction.cc.

{
  // Create the event skeleton, marking the residue as an undecayed
  // intermediate state (it will be allowed to decay later if nuclear
  // de-excitation is enabled)
  auto event = marley::Reaction::make_event_object( KEa, pc_cm,
    cos_theta_c_cm, phi_c_cm, Ec_cm, Ed_cm,
    marley_hepmc3::NUHEPMC_UNDECAYED_RESIDUE_STATUS );
 
  // Attach the charge attributes for the target and residue
  this->set_charge_attributes( event );
 
  // Add the nuclear level attributes needed to keep track of the residue's
  // de-excitation state
  auto residue = marley_hepmc3::get_residue( *event );
  this->set_nuclear_residue_attributes( residue, E_level, twoJ, P );
 
  return event;
}

References marley::Reaction::make_event_object(), set_charge_attributes(), and set_nuclear_residue_attributes().

Referenced by marley::ContinuumNuclearReaction::create_event(), and marley::DiscreteNuclearReaction::create_event().

max_level_energy()

double marley::NuclearReaction::max_level_energy

(

double

KEa

)

const

Get the maximum possible excitation energy (MeV) of the final-state residue that is kinematically allowed.

Parameters

KEa	Projectile lab-frame kinetic energy (MeV)

Definition at line 90 of file NuclearReaction.cc.

                                                                 {
  // Calculate the total CM frame energy using known quantities
  // from the lab frame
  double E_CM = std::sqrt( std::pow(ma_ + mb_, 2) + 2*mb_*KEa );
  // The maximum level energy is achieved when the final state
  // particles are produced at rest in the CM frame. Subtracting
  // the ground-state rest masses of particles c and d from the
  // total CM energy leaves us with the energy available to create
  // an excited level in the residue (particle d).
  return E_CM - mc_ - md_gs_;
}

References marley::Reaction::ma_, marley::Reaction::mb_, marley::Reaction::mc_, and md_gs_.

Referenced by marley::DiscreteNuclearReaction::create_event(), marley::DiscreteNuclearReaction::diff_xs(), and marley::DiscreteNuclearReaction::summed_xs_helper().

set_charge_attributes()

void marley::NuclearReaction::set_charge_attributes ( std::shared_ptr< HepMC3::GenEvent > & event ) const

protected

Helper function that sets the charges of the target and residue in an otherwise complete event record.

Definition at line 126 of file NuclearReaction.cc.

{
  // Assume that the target is a neutral atom (q_b = 0)
  auto target = marley_hepmc3::get_target( *event );
  marley_hepmc3::set_particle_charge( *target, 0 );
 
  // Assign the correct charge to the residue
  auto residue = marley_hepmc3::get_residue( *event );
  marley_hepmc3::set_particle_charge( *residue, q_d_ );
}

References q_d_.

Referenced by make_nuclear_event_object(), and make_nuclear_event_object().

set_description()

void marley::NuclearReaction::set_description ( )

protectedvirtual

Creates the description string based on the PDG code values for the initial and final particles.

Reimplemented in marley::ContinuumNuclearReaction, and marley::DiscreteNuclearReaction.

Definition at line 117 of file NuclearReaction.cc.

                                            {
  description_ = marley_utils::get_particle_symbol( pdg_a_ ) + " + ";
  description_ += std::to_string( Ai_ );
  description_ += marley_utils::element_symbols.at( Zi_ ) + " --> ";
  description_ += marley_utils::get_particle_symbol( pdg_c_ ) + " + ";
  description_ += std::to_string( Af_ );
  description_ += marley_utils::element_symbols.at( Zf_ );
}

References Af_, Ai_, marley::Reaction::description_, marley::Reaction::pdg_a_, marley::Reaction::pdg_c_, Zf_, and Zi_.

Referenced by NuclearReaction(), marley::ContinuumNuclearReaction::set_description(), and marley::DiscreteNuclearReaction::set_description().

set_nuclear_residue_attributes()

void marley::NuclearReaction::set_nuclear_residue_attributes ( const std::shared_ptr< HepMC3::GenParticle > & residue, double E_level, int twoJ, const marley::Parity & P ) const

protected

Helper function that adds the nuclear level attributes ( \( E_x \), \( 2J \), and parity) needed to keep track of the residue's de-excitation state to an otherwise complete event record.

Parameters

residue	GenParticle object for the residue
E_level	Residue excitation energy (MeV)
twoJ	Two times the residue spin
P	Intrinsic parity of the residue

Definition at line 138 of file NuclearReaction.cc.

{
  // Add attributes needed to keep track of the nuclear de-excitation state
  residue->add_attribute( "Ex",
    std::make_shared< HepMC3::DoubleAttribute >(E_level) );
  residue->add_attribute( "twoJ",
    std::make_shared< HepMC3::IntAttribute >(twoJ) );
  residue->add_attribute( "parity",
    std::make_shared< HepMC3::IntAttribute >(static_cast<int>( P )) );
}

References HepMC3::GenParticle::add_attribute().

Referenced by make_nuclear_event_object(), and make_nuclear_event_object().

threshold_kinetic_energy()

double marley::NuclearReaction::threshold_kinetic_energy ( ) const

overridevirtual

Get the minimum lab-frame kinetic energy (MeV) of the projectile that allows this reaction to proceed via a transition to the residue's ground state.

Implements marley::Reaction.

Definition at line 102 of file NuclearReaction.cc.

                                                             {
  return KEa_threshold_;
}

References KEa_threshold_.

weak_nuclear_charge()

double marley::NuclearReaction::weak_nuclear_charge

(

)

const

Computes the weak nuclear charge \( Q_W = N - (1 - 4\sin^2\theta_W)Z \) for the target nucleus

In the expression above, \( N \) ( \(Z\)) is the neutron (proton) number of the target nucleus and \( \theta_W \) is the weak mixing angle.

Definition at line 109 of file NuclearReaction.cc.

{
  int Ni = Ai_ - Zi_;
  double Qw = Ni - ( 1. - 4.*marley_utils::sin2thetaw )*Zi_;
  return Qw;
}

References Ai_, and Zi_.

Referenced by marley::DiscreteNuclearReaction::diff_xs().

Member Data Documentation

Af_

int marley::NuclearReaction::Af_

protected

Residue mass number.

Definition at line 139 of file NuclearReaction.hh.

Referenced by NuclearReaction(), and set_description().

Ai_

int marley::NuclearReaction::Ai_

protected

Target mass number.

Definition at line 137 of file NuclearReaction.hh.

Referenced by NuclearReaction(), set_description(), and weak_nuclear_charge().

KEa_threshold_

double marley::NuclearReaction::KEa_threshold_

protected

Lab-frame kinetic energy of the projectile at threshold for this reaction (i.e., the residue is produced in its ground state, and all final-state particles are at rest in the CM frame)

Definition at line 148 of file NuclearReaction.hh.

Referenced by NuclearReaction(), marley::ContinuumNuclearReaction::create_event(), marley::DiscreteNuclearReaction::create_event(), and threshold_kinetic_energy().

md_gs_

double marley::NuclearReaction::md_gs_

protected

Ground state mass (MeV) of the residue.

Definition at line 134 of file NuclearReaction.hh.

Referenced by NuclearReaction(), marley::ContinuumNuclearReaction::create_event(), marley::DiscreteNuclearReaction::create_event(), marley::DiscreteNuclearReaction::diff_xs(), marley::ContinuumNuclearReaction::get_Ec_from_Ex(), max_level_energy(), and marley::ContinuumNuclearReaction::reassign_sub_continuum().

q_d_

int marley::NuclearReaction::q_d_

protected

Net charge of the residue (in units of the proton charge) following this reaction.

Definition at line 143 of file NuclearReaction.hh.

Referenced by NuclearReaction(), and set_charge_attributes().

Zf_

int marley::NuclearReaction::Zf_

protected

Residue atomic number.

Definition at line 138 of file NuclearReaction.hh.

Referenced by NuclearReaction(), and set_description().

Zi_

int marley::NuclearReaction::Zi_

protected

Target atomic number.

Definition at line 136 of file NuclearReaction.hh.

Referenced by NuclearReaction(), set_description(), and weak_nuclear_charge().

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

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