g4db::ElementXsecCache Class Reference

The cache of already computed cross sections. More...

#include <ElementXsecCache.h>

Collaboration diagram for g4db::ElementXsecCache:

Public Member Functions
	ElementXsecCache ()=default
	Default constructor. More...
	ElementXsecCache (std::shared_ptr< PrototypeModel > model)
	Constructor with a model to calculate the cross section.
G4double	get (G4double energy, G4double A, G4double Z)
	Get the value of the cross section for the input variables and calculate the cross section if it wasn't calculated before. More...
void	stream (std::ostream &o) const
	Stream the entire table into the output stream. More...

Private Types
typedef unsigned long int	key_t
	The type for the key we use in the cache.

Private Member Functions
key_t	computeKey (G4double energy, G4double A, G4double Z) const
	Compute a key for the cache map Generating a unique key after making the energy [MeV] an integer. More...

Private Attributes
std::map< key_t, G4double >	the_cache_
	the actual map from cache keys to calculated cross sections
std::shared_ptr< PrototypeModel >	model_
	shared pointer to the model for calculating cross sections

Static Private Attributes
static const key_t	MAX_A {1000}
	The maximum value of A.
static const key_t	MAX_E {1500000}
	The maximum value for energy [MeV].

Friends
std::ostream &	operator<< (std::ostream &o, const ElementXsecCache c)
	Overload the streaming operator for ease. More...

Detailed Description

The cache of already computed cross sections.

We make a specific class for the cache in order to keep the key encoding/decoding process in a central location.

Constructor & Destructor Documentation

ElementXsecCache()

g4db::ElementXsecCache::ElementXsecCache ( )

default

Default constructor.

Does nothing interesting, but no model for calculating cross section has been set.

Member Function Documentation

computeKey()

ElementXsecCache::key_t g4db::ElementXsecCache::computeKey ( G4double  energy, G4double  A, G4double  Z  ) const

private

Compute a key for the cache map Generating a unique key after making the energy [MeV] an integer.

The atomic mass (A) and charge (Z) are given by Geant4 as doubles as well, so I cast them to integers before computing the key.

This is what you would edit if you want a more/less find-grained cache of Xsecs. Right now, since the internal unit of energy in Geant4 is MeV, the cache is binned at the 1MeV scale.

Parameters

[in]	energy	Energy of incident lepton [MeV]
[in]	A	atomic mass of element [atomic mass units]
[in]	Z	atomic number of element [num protons]

Returns

unsigned integer cache key for these three inputs

Note

This implicitly converts the input double to a unsigned long int. Since the internal units for energy are MeV, this means the cache is binned at a 1 MeV level. The atomic inputs A and Z also undergo the implicit conversion; however, this is less of a worry since different elements are separated by at least one whole unit in A and Z.

get()

G4double g4db::ElementXsecCache::get	(	G4double	energy,
		G4double	A,
		G4double	Z
	)

Get the value of the cross section for the input variables and calculate the cross section if it wasn't calculated before.

Exceptions

std::runtime_error

if no model is available for calculating cross sections

Parameters

[in]	energy	Energy of incident lepton [MeV]
[in]	A	atomic mass of element [atomic mass units]
[in]	Z	atomic number of element [num protons]

Returns

cross section corresponding to the input parameters (including units Geant4 style)

stream()

void g4db::ElementXsecCache::stream

(

std::ostream &

o

)

const

Stream the entire table into the output stream.

Parameters

[in,out]

o

ostream to write to

Friends And Related Function Documentation

operator<<

std::ostream& operator<< ( std::ostream &  o, const ElementXsecCache  c  )

friend

Overload the streaming operator for ease.

Parameters

[in]	o	ostream to write to
[in]	c	cache to write out

Returns

modified ostream

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

• include/G4DarkBreM/ElementXsecCache.h
• src/G4DarkBreM/ElementXsecCache.cxx