A neutrino-nucleus reaction. More...

#include <NuclearReaction.hh>

Inheritance diagram for marley::NuclearReaction:

Public Types
enum class	CoulombMode { NO_CORRECTION , FERMI_FUNCTION , EMA , MEMA , FERMI_AND_EMA , FERMI_AND_MEMA }
	Enumerated type used to set the method for handling Coulomb corrections for CC nuclear reactions.

Public Types inherited from marley::Reaction
enum	ProcessType { NeutrinoCC = 0 , AntiNeutrinoCC = 1 , NC = 2 , NuElectronElastic = 3 }
	Enumerated type describing the kind of scattering process represented by a Reaction. More...

Public Member Functions
	NuclearReaction (ProcessType pt, int pdg_a, int pdg_b, int pdg_c, int pdg_d, int q_d, const std::shared_ptr< std::vector< marley::MatrixElement > > &mat_els)

virtual marley::TargetAtom	atomic_target () const override final
	Returns the target atom involved in this reaction. More...

double	coulomb_correction_factor (double beta_rel_cd) const

CoulombMode	coulomb_mode () const

virtual marley::Event	create_event (int particle_id_a, double KEa, marley::Generator &gen) const override
	Produces a two-two scattering Event that proceeds via this reaction. More...

double	diff_xs (const marley::MatrixElement &mat_el, double KEa, double cos_theta_c_cm) const
	Differential cross section \(d\sigma/d\cos\theta_{c}^{\mathrm{CM}}\) (MeV^-2) evaluated in the center-of-momentum frame for a transition to a particular final nuclear level. More...

virtual double	diff_xs (int pdg_a, double KEa, double cos_theta_c_cm) const override
	Differential cross section \(d\sigma/d\cos\theta_{c}^{\mathrm{CM}}\) (MeV^-2) summed over all kinematically-allowed final nuclear levels. More...

double	ema_factor (double beta_rel_cd, bool &ok, bool modified_ema) const

double	fermi_function (double beta_c) const
	Compute the Fermi function More...

const std::vector< marley::MatrixElement > &	matrix_elements () const
	Allows access to the owned vector of MatrixElement objects.

double	max_level_energy (double KEa) const
	Get the maximum possible excitation energy (MeV) of the final-state residue that is kinematically allowed. More...

void	set_coulomb_mode (CoulombMode mode)
	Set the method for handling Coulomb corrections for this reaction.

void	set_decay_scheme (marley::DecayScheme *scheme)
	Sets the DecayScheme object to use for sampling excited levels in the residue.

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.

virtual double	total_xs (const marley::MatrixElement &me, double KEa, double &beta_c_cm, bool check_max_E_level=true) const
	Total cross section (MeV^-2) for a given final nuclear level. More...

virtual double	total_xs (int pdg_a, double KEa) const override
	Total reaction cross section (MeV^-2), including all kinematically-allowed final nuclear levels. More...

double	weak_nuclear_charge () const

Public Member Functions inherited from marley::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.

Static Public Member Functions
static CoulombMode	coulomb_mode_from_string (const std::string &str)
	Convert a string to a CoulombMode value.

static std::string	string_from_coulomb_mode (CoulombMode mode)
	Convert a CoulombMode value to a string.

Static Public Member Functions inherited from marley::Reaction
static int	get_ejectile_pdg (int pdg_a, ProcessType proc_type)

static std::vector< std::unique_ptr< Reaction > >	load_from_file (const std::string &filename, marley::StructureDatabase &db)

static std::string	proc_type_to_string (const ProcessType &pt)

Protected Member Functions
virtual marley::Event	make_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 override
	Helper function used by NuclearReaction::create_event()

double	sample_cos_theta_c_cm (const marley::MatrixElement &matrix_el, double beta_c_cm, marley::Generator &gen) const
	Samples a polar angle cosine for the ejectile using the relevant portion of the reaction nuclear matrix element. More...

void	set_description ()
	Creates the description string based on the PDG code values for the initial and final particles.

double	summed_xs_helper (int pdg_a, double KEa, double cos_theta_c_cm, std::vector< double > *level_xsecs, bool differential) const

Protected Member Functions inherited from marley::Reaction
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. More...

Protected Attributes
int	Af_
	Residue mass number.

int	Ai_
	Target mass number.

CoulombMode	coulomb_mode_ = CoulombMode::FERMI_AND_MEMA
	The method to use when computing Coulomb corrections (if needed) for this reaction.

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)

std::shared_ptr< std::vector< marley::MatrixElement > >	matrix_elements_
	Matrix elements representing all of the possible nuclear transitions that may be caused by this reaction.

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.

Static Protected Attributes
static std::map< CoulombMode, std::string >	coulomb_mode_string_map_

Additional Inherited Members
Static Protected Member Functions inherited from marley::Reaction
static const std::vector< int > &	get_projectiles (ProcessType proc_type)

Detailed Description

A neutrino-nucleus reaction.

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::shared_ptr< std::vector< marley::MatrixElement > > &	mat_els
	)

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
mat_els	A vector of MatrixElement objects that should be used to compute cross sections for this NuclearReaction

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.

◆ coulomb_correction_factor()

double marley::NuclearReaction::coulomb_correction_factor ( double beta_rel_cd ) const

Computes an approximate correction factor to account for effects of the Coulomb potential when calculating cross sections

Parameters

beta_rel_cd The relative speed of the final particles c and d (dimensionless)

◆ coulomb_mode()

CoulombMode marley::NuclearReaction::coulomb_mode ( ) const

inline

Return the method used by this reaction for handling Coulomb corrections

◆ create_event()

marley::Event marley::NuclearReaction::create_event	(	int	particle_id_a,
		double	KEa,
		marley::Generator &	gen
	)		const

overridevirtual

Produces a two-two scattering Event that proceeds via this reaction.

Todo:: Add more error checks to NuclearReaction::create_event as necessary

Todo:: Revisit the equipartition assumption made here in favor of something better motivated.

Implements marley::Reaction.

◆ diff_xs() [1/2]

double marley::NuclearReaction::diff_xs	(	const marley::MatrixElement &	mat_el,
		double	KEa,
		double	cos_theta_c_cm
	)		const

Differential cross section \(d\sigma/d\cos\theta_{c}^{\mathrm{CM}}\) (MeV^-2) evaluated in the center-of-momentum frame for a transition to a particular final nuclear level.

Parameters

mat_el	MatrixElement object describing the transition to the final nuclear level
KEa	Lab-frame projectile kinetic energy (MeV)
cos_theta_c_cm	Ejectile scattering cosine as measured in the CM frame

◆ diff_xs() [2/2]

double marley::NuclearReaction::diff_xs	(	int	pdg_a,
		double	KEa,
		double	cos_theta_c_cm
	)		const

overridevirtual

Differential cross section \(d\sigma/d\cos\theta_{c}^{\mathrm{CM}}\) (MeV^-2) summed over all kinematically-allowed final nuclear levels.

Parameters

pdg_a	PDG code for the projectile
KEa	Lab-frame kinetic energy (MeV) of the projectile
cos_theta_c_cm	CM frame scattering cosine of the ejectile

Note: This function returns 0. if pdg_a != pdg_a_.

Implements marley::Reaction.

◆ ema_factor()

double marley::NuclearReaction::ema_factor	(	double	beta_rel_cd,
		bool &	ok,
		bool	modified_ema
	)		const

Computes a Coulomb correction factor according to the effective momentum approximation. See J. Engel, Phys. Rev. C 57, 2004 (1998)

Parameters

	beta_rel_cd	The relative speed of the final particles c and d (dimensionless)
[out]	ok	Flag that is set to false if subtracting the Coulomb potential pulls the event below threshold
	modified_ema	If true, the modified EMA correction factor will be returned instead of that specified by the original EMA

◆ fermi_function()

double marley::NuclearReaction::fermi_function ( double beta_c ) const

Compute the Fermi function

Parameters

beta_c Dimensionless speed of the ejectile

◆ 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)

◆ sample_cos_theta_c_cm()

double marley::NuclearReaction::sample_cos_theta_c_cm	(	const marley::MatrixElement &	matrix_el,
		double	beta_c_cm,
		marley::Generator &	gen
	)		const

protected

Samples a polar angle cosine for the ejectile using the relevant portion of the reaction nuclear matrix element.

Parameters

m_type	Integer representing the type of transition (0 = Fermi, 1 = Gamow-Teller)
beta_c_cm	Dimensionless speed of the ejectile in the CM frame
gen	Reference to the Generator to use for random sampling

◆ summed_xs_helper()

double marley::NuclearReaction::summed_xs_helper	(	int	pdg_a,
		double	KEa,
		double	cos_theta_c_cm,
		std::vector< double > *	level_xsecs,
		bool	differential
	)		const

protected

Helper function for total_xs and summed_diff_xs()

Parameters

pdg_a	PDG code for the projectile
KEa	Lab-frame projectile kinetic energy (MeV)
cos_theta_c_cm	CM frame scattering cosine for the ejectile
level_xsecs	If this pointer is not nullptr, then the std::vector<double> that it points to will be cleared and loaded with the partial cross sections to each individual nuclear level included in the sum. This feature is helpful when computing weights for sampling a nuclear transition in create_event().
differential	Whether the total cross section (false) or the differential cross section (true, \(d\sigma/d\cos\theta_{c}^{\mathrm{CM}}\)) should be summed over all kinematically accessible nuclear levels by this function

Returns: The requested cross section (MeV^-2)

Todo:: Consider whether you should use an exception if pdg_a != pdg_a_

◆ total_xs() [1/2]

double marley::NuclearReaction::total_xs	(	const marley::MatrixElement &	me,
		double	KEa,
		double &	beta_c_cm,
		bool	check_max_E_level = `true`
	)		const

virtual

Total cross section (MeV^-2) for a given final nuclear level.

Parameters

	me	MatrixElement object describing the transition to the final nuclear level
	KEa	Lab-frame projectile kinetic energy (MeV)
[out]	beta_c_cm	After this function is called, this variable will contain the (dimensionless) speed of the ejectile as measured in the center of momentum frame
	check_max_E_level	Whether to check the reaction threshold via a call to max_level_energy(). If this argument is set to false, then the check will be skipped.

◆ total_xs() [2/2]

double marley::NuclearReaction::total_xs	(	int	pdg_a,
		double	KEa
	)		const

overridevirtual

Total reaction cross section (MeV^-2), including all kinematically-allowed final nuclear levels.

Parameters

pdg_a	PDG code for the projectile
KEa	Lab-frame kinetic energy (MeV) of the projectile

Returns: Reaction total cross section (MeV^-2)

Note: This function returns 0. if pdg_a != pdg_a_.

Implements marley::Reaction.

◆ 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.

Member Data Documentation

◆ coulomb_mode_string_map_

std::map< CMode, std::string > marley::NuclearReaction::coulomb_mode_string_map_

staticprotected

Initial value:

=
{
  { CMode::NO_CORRECTION, "none" },
  { CMode::FERMI_FUNCTION, "Fermi" },
  { CMode::EMA, "EMA" },
  { CMode::MEMA, "MEMA" },
  { CMode::FERMI_AND_EMA, "Fermi-EMA" },
  { CMode::FERMI_AND_MEMA, "Fermi-MEMA" },
}

Helper map used by the methods to convert a CoulombMode value to and from a std::string

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

/Users/gardiner/marley/include/marley/NuclearReaction.hh
/Users/gardiner/marley/src/NuclearReaction.cc

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Static Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ NuclearReaction()

Member Function Documentation

◆ atomic_target()

◆ coulomb_correction_factor()

◆ coulomb_mode()

◆ create_event()

◆ diff_xs() [1/2]

◆ diff_xs() [2/2]

◆ ema_factor()

◆ fermi_function()

◆ max_level_energy()

◆ sample_cos_theta_c_cm()

◆ summed_xs_helper()

◆ total_xs() [1/2]

◆ total_xs() [2/2]

◆ weak_nuclear_charge()

Member Data Documentation

◆ coulomb_mode_string_map_