g4db::ElementXsecInterpolation Class Reference

Interpolation of cross sections by element. More...

#include <ElementXsecInterpolation.h>

Collaboration diagram for g4db::ElementXsecInterpolation:

Classes
class	SampleSet
	A sample set is two parallel vectors limited to operate for our interpolation goal. More...

Public Member Functions
	ElementXsecInterpolation ()=default
	Default constructor. More...
	ElementXsecInterpolation (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. More...
void	stream (std::ostream &o) const
	Stream the table of sample points into the output stream. More...

Private Attributes
std::map< int, SampleSet >	the_samples_
	each element has its own set of sample points
std::shared_ptr< PrototypeModel >	model_
	shared pointer to the model for calculating cross sections

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

Detailed Description

Interpolation of cross sections by element.

The interpolation method is a modified quadratic interpolation where the main modification is - since we have a way to calculate new sample points - we expand the set of sample points if a cross section is requested for a energy and/or element outside of our current sample range.

Constructor & Destructor Documentation

ElementXsecInterpolation()

g4db::ElementXsecInterpolation::ElementXsecInterpolation ( )

default

Default constructor.

Does nothing interesting, but no model for calculating cross section has been set. If interpolation is attempted with a default-constructed interpolator, an exception will be thrown.

Member Function Documentation

get()

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

Get the value of the cross section for the input variables.

For the interpolation to be successful, we impose the kinematic limit immediately - i.e. if energy is less than twice the A' mass, the cross section is zero.

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)

Note

Implicit conversion to integer from the double form of Z. This may not function properly if users have a custom element that is an averaged Z, but since elements close in Z behave similarly, this may not matter either.

When there is no entry for an element yet, we initialize the samples by calculating the cross section in 10% energy steps from the kinematic minimum up to the requested energy.

When the requested energy is below the lowest sample point, we determine two more samples. One at the requested energy and one below it.

When the requested energy is above the highest sample point, we determine two more samples. One at the requested energy and one above it.

When the requested energy is within the range set by our samples, we do a quadratic interpolation using the three points that enclose the requested energy.

We do the interpolation with the first set of three points that encloses the requested energy, so this prefers the point set that has two samples below and one above.

stream()

void g4db::ElementXsecInterpolation::stream

(

std::ostream &

o

)

const

Stream the table of sample points 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 ElementXsecInterpolation  c  )

friend

Overload the streaming operator for ease.

Parameters

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

Returns

modified ostream

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

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