The Isotope represents a nuclide at some temperature. More...

#include "pinspec/src/Isotope.h"

Public Member Functions
	Isotope (char *_isotope_name)
	Isotope constructor. More...

virtual	~Isotope ()
	Isotope destructor deletes arrays of cross-section values that have been assigned to this isotope.

void	parseName (char *isotope_name)
	Parse input name and set atomic number for isotope.

void	makeFissionable ()
	Inform isotope that it is fissionable.

char *	getIsotopeName () const
	Returns the name of the of isotope. More...

int	getUid () const
	Returns the unique ID auto-generated for the isotope. More...

int	getA () const
	Returns the atomic number of this isotope. More...

float	getAlpha () const
	Returns the alpha $\alpha = ((A-1)/(A+1))^2$ values for this isotope. More...

float	getTemperature () const
	Return the temperature in degrees Kelvin for this isotope. More...

float	getMuAverage () const
	Return the average value of the cosine of the scattering angle. More...

bool	isFissionable () const
	Return whether this isotope is fissionable (true) or not (false) More...

float	getThermalScatteringCutoff ()
	Return the thermal scattering high energy cutoff. More...

int	getNumXSEnergies (char *xs_type) const
	Returns the number of energies for a particular cross-section type. More...

float	getElasticXS (float energy) const
	Returns the microscopic elastic scattering cross-section value for some energy. More...

float	getElasticXS (int energy_index) const
	Returns the microscopic elastic cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data. More...

float	getAbsorptionXS (float energy) const
	Returns the microscopic absorption cross-section value for some energy. More...

float	getAbsorptionXS (int energy_index) const
	Returns the microscopic absorption cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data. More...

float	getCaptureXS (float energy) const
	Returns the microscopic capture cross-section value for some energy. More...

float	getCaptureXS (int energy_index) const
	Returns the microscopic capture cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data. More...

float	getFissionXS (float energy) const
	Returns the microscopic fission cross-section value for some energy. More...

float	getFissionXS (int energy_index) const
	Returns the microscopic fission cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data. More...

float	getTotalXS (float energy) const
	Returns the microscopic total cross-section value for some energy. More...

float	getTotalXS (int energy_index) const
	Returns the microscopic total cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data. More...

float	getTransportXS (int energy_index) const
	Returns the microscopic transport cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data. More...

float	getTransportXS (float energy) const
	Returns the microscopic transport cross-section value for some energy. More...

bool	usesThermalScattering ()
	This method returns true if the thermal scattering distributions for this isotope are to be used when sampling outgoing collision energy. More...

bool	isRescaled () const
	This method returns whether or not the Isotope's cross-sections have been rescaled to a uniform lethargy grid. More...

int	getEnergyGridIndex (float energy) const
	This method returns the index for a certain energy (eV) into the Isotope's uniform lethargy grid. More...

void	retrieveXSEnergies (float energies, int num_xs, char xs_type) const
	Fills an array with cross-section energy values. More...

void	retrieveXS (float xs, int num_xs, char xs_type) const
	Fills an array with microscopic cross-section values. More...

void	setElasticXS (double energies, int num_energies, double elastic_xs, int num_xs)
	Sets the elastic cross-section data for this isotope. More...

void	setCaptureXS (double energies, int num_energies, double capture_xs, int num_xs)
	Sets the capture cross-section data for this isotope. More...

void	setFissionXS (double energies, int num_energies, double fission_xs, int num_xs)
	Sets the fission cross-section data for this isotope. More...

void	setMultigroupElasticXS (double energies, int num_energies, double elastic_xs, int num_xs)
	Sets the multigroup elastic cross-section data for this isotope. More...

void	setMultigroupCaptureXS (double energies, int num_energies, double capture_xs, int num_xs)
	Sets the multigroup capture cross-section data for this isotope. More...

void	setMultigroupFissionXS (double energies, int num_energies, double fission_xs, int num_xs)
	Sets the multigroup fission cross-section data for this isotope. More...

void	loadXS (char *xs_type)
	Load the ENDF cross-section data for a particular cross-section from an ASCII file into the appropriate array for this isotope. More...

void	setA (int A)
	Set the atomic number and update alpha, eta and rho. More...

void	setTemperature (float T)
	Set the temperature of the isotope in degrees Kelvin. More...

void	neglectThermalScattering ()
	Informs isotope not to use thermal scattering to sample outgoing collision energies.

void	setThermalScatteringCutoff (float cutoff_energy)
	Sets the thermal scattering high energy cutoff energy. More...

void	useThermalScattering ()
	Informs isotope to use thermal scattering to sample outgoing collision energies.

Isotope *	clone ()
	This method clones a given Isotope class object by executing a deep copy of all of the Isotope's class attributes and giving them to a new Isotope class object. More...

void	sampleCollisionType (neutron *neutron)
	Determines a random collision type based on the values of each of the isotope's cross-section values at a given enery. More...

float	getDistanceTraveled (neutron *neutron)
	For a given neutron, this method samples a distance traveled to next collision. More...

void	collideNeutron (neutron *neutron)
	For a given energy, this method samples a collision type, updates the neutron's outgoing energy and kills the neutron if it sampled absorption or leakage. More...

float	getThermalScatteringEnergy (float energy)
	For a given neutron energy (eV) in a scattering collision, this function returns the outgoing energy in eV, , for the collision based on its thermal scattering distributions. More...

int	getNumThermalCDFs ()
	Returns the number of thermal scattering CDFs. More...

int	getNumThermalCDFBins ()
	Returns the number of energy bins for each thermal scattering CDF. More...

void	retrieveThermalCDFs (float *cdfs, int num_values)
	Loads an input array with the values for each of the isotope's thermal CDFs. More...

void	retrieveThermalPDFs (float *pdfs, int num_values)
	Loads an input array with the energies for each of the isotope's thermal PDFs. More...

void	retrieveEtokT (float *E_to_kT, int num_cdfs)
	Loads an input array with the $\frac{E}{kT}$ values for each thermal scattering CDF. More...

void	retrieveEprimeToE (float *Eprime_to_E, int num_bins)
	Loads an input array with the $\frac{E'}{E}$ values for each thermal scattering CDF. More...

Private Member Functions
void	loadXS ()
	Load the ENDF cross-section data from ASCII files into arrays for this isotope. More...

void	setElasticXS (float elastic_xs, float elastic_xs_energies, int num_elastic_xs)
	Set the elastic cross-section for this isotope. More...

void	setCaptureXS (float capture_xs, float capture_xs_energies, int num_capture_xs)
	Set the capture cross-section for this isotope. More...

void	setFissionXS (float fission_xs, float fission_xs_energies, int num_fission_xs)
	Set the fission cross-section for this isotope. More...

void	rescaleXS (float start_energy, float end_energy, int num_energies)
	Rescales all of the isotope's cross-sections onto a uniform lethargy grid. More...

void	generateAbsorptionXS (float start_energy, float end_energy, int num_energies)
	Computes the microscopic absorption cross-section from the isotope's capture and fission (if applicable) cross-sections. More...

void	generateTotalXS (float start_energy, float end_energy, int num_energies)
	Computes the microscopic total cross-section from the isotope's capture, elastic scatter and fission (if applicable) cross-sections. More...

void	initializeThermalScattering (float start_energy, float end_energy, int num_bins, int num_distributions)
	This method initializes the probability distributions for thermal scattering. More...

float	thermalScatteringProb (float E_prime_to_E, int dist_index)
	This function computes the thermal scattering probability for a ratio of initial to final energies. More...

Private Attributes
char *	_isotope_name

int	_uid

int	_A

int	_A_squared

int	_A_plus_one_squared

float	_alpha

float	_eta

float	_rho

float	_AO

float	_T

float	_mu_avg

bool	_fissionable

bool	_rescaled

int	_num_elastic_xs

float *	_elastic_xs

float *	_elastic_xs_energies

bool	_elastic_rescaled

int	_num_capture_xs

float *	_capture_xs

float *	_capture_xs_energies

bool	_capture_rescaled

int	_num_fission_xs

float *	_fission_xs

float *	_fission_xs_energies

bool	_fission_rescaled

int	_num_absorb_xs

float *	_absorb_xs

float *	_absorb_xs_energies

int	_num_total_xs

float *	_total_xs

float *	_total_xs_energies

int	_num_energies

float	_start_lethargy

float	_end_lethargy

float	_delta_lethargy

bool	_use_thermal_scattering

float	_thermal_cutoff

float	_kB

int	_num_thermal_cdfs

int	_num_thermal_cdf_bins

float *	_thermal_dist

float **	_thermal_cdfs

float *	_E_to_kT

float *	_Eprime_to_E

Static Private Attributes
static int	_n = 1

Detailed Description

The Isotope represents a nuclide at some temperature.

The Isotope class represents a nuclide and all of its properties which are relevant to reactor physics calculations.

Constructor & Destructor Documentation

Isotope::Isotope ( char * isotope_name )

Isotope constructor.

Searches the cross-section library for appropriately named files using the isotope name and loads the capture, scatter, and fission (if file is found) cross-sectoins. By default, the constructor rescales the cross-sections onto a uniform lethargy grid of 100,000 values between 1E-5 eV and 20 MeV. In addition, the constructor creates thermal scattering CDFs for the isotope at 300K by default.

Member Function Documentation

Isotope * Isotope::clone ( )

This method clones a given Isotope class object by executing a deep copy of all of the Isotope's class attributes and giving them to a new Isotope class object.

Returns: a pointer to the new cloned Isotope class object

void Isotope::collideNeutron ( neutron * neutron )

For a given energy, this method samples a collision type, updates the neutron's outgoing energy and kills the neutron if it sampled absorption or leakage.

Parameters

neutron the neutron struct of interest

void Isotope::generateAbsorptionXS	(	float	start_energy,
		float	end_energy,
		int	num_energies
	)

private

Computes the microscopic absorption cross-section from the isotope's capture and fission (if applicable) cross-sections.

This class method computes the absorption cross-section on a uniform lethargy grid.

Parameters

start_energy	the highest lethargy value in the grid
end_energy	the lowest lethargy value in the grid
num_energies	the number of energies represented in the grid

void Isotope::generateTotalXS	(	float	start_energy,
		float	end_energy,
		int	num_energies
	)

private

Computes the microscopic total cross-section from the isotope's capture, elastic scatter and fission (if applicable) cross-sections.

This class method computes the total cross-section on a uniform lethargy grid.

Parameters

start_energy	the highest lethargy value in the grid
end_energy	the lowest lethargy value in the grid
num_energies	the number of energies represented in the grid

int Isotope::getA ( ) const

Returns the atomic number of this isotope.

Returns: the atomic number

float Isotope::getAbsorptionXS ( float energy ) const

Returns the microscopic absorption cross-section value for some energy.

Uses linear interpolation to compute the cross-section at a a certain energy (eV).

Parameters

energy the energy (eV) of interest

Returns: the microscopic absorption cross-section

float Isotope::getAbsorptionXS ( int energy_index ) const

Returns the microscopic absorption cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data.

Parameters

energy_index the index into the energy array

Returns: the microscopic absorption cross-section

float Isotope::getAlpha ( ) const

Returns the alpha $\alpha = ((A-1)/(A+1))^2$ values for this isotope.

Returns: alpha

float Isotope::getCaptureXS ( float energy ) const

Returns the microscopic capture cross-section value for some energy.

Uses linear interpolation to compute the cross-section at a a certain energy (eV).

Parameters

energy the energy (eV) of interest

Returns: the microscopic absorption cross-section

float Isotope::getCaptureXS ( int energy_index ) const

Returns the microscopic capture cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data.

Parameters

energy_index the index into the energy array

Returns: the microscopic capture cross-section

float Isotope::getDistanceTraveled ( neutron * neutron )

For a given neutron, this method samples a distance traveled to next collision.

Parameters

neutron the neutron struct of interest

Returns: the distance traveled

float Isotope::getElasticXS ( float energy ) const

Returns the microscopic elastic scattering cross-section value for some energy.

Uses linear interpolation to compute the cross-section at a a certain energy (eV).

Parameters

energy the energy (eV) of interest

Returns: the microscopic elastic scattering cross-section

float Isotope::getElasticXS ( int energy_index ) const

Returns the microscopic elastic cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data.

Parameters

energy_index the index into the energy array

Returns: the microscopic elastic cross-section

int Isotope::getEnergyGridIndex ( float energy ) const

inline

This method returns the index for a certain energy (eV) into the Isotope's uniform lethargy grid.

The index computed is that of nearest energy less than or equal to the input energy.

Parameters

energy the energy (eV) of interest

Returns: the index into the uniform lethargy grid

float Isotope::getFissionXS ( float energy ) const

Returns the microscopic fission cross-section value for some energy.

Uses linear interpolation to compute the cross-section at a a certain energy (eV).

Parameters

energy the energy (eV) of interest

Returns: the microscopic fission cross-section

float Isotope::getFissionXS ( int energy_index ) const

Returns the microscopic fission cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data.

Parameters

energy_index the index into the energy array

Returns: the microscopic fission cross-section

char * Isotope::getIsotopeName ( ) const

Returns the name of the of isotope.

Returns: character array with name of isotope

float Isotope::getMuAverage ( ) const

Return the average value of the cosine of the scattering angle.

Returns the average value of cosine of theta for this isotope in a scattering collision: $\left<\mu\right> = \frac{2}{3A}$

Returns: the average for mu

int Isotope::getNumThermalCDFBins ( )

Returns the number of energy bins for each thermal scattering CDF.

Returns: the number of energy bins per thermal scattering CDF

int Isotope::getNumThermalCDFs ( )

Returns the number of thermal scattering CDFs.

Returns: the number of thermal scattering CDFs

int Isotope::getNumXSEnergies ( char * xs_type ) const

Returns the number of energies for a particular cross-section type.

Returns the number of energies for 'capture', 'elastic', 'fission', 'fission' and 'absorption cross-section types.

Parameters

xs_type a character array for the xs_type

Returns

float Isotope::getTemperature ( ) const

Return the temperature in degrees Kelvin for this isotope.

Returns: the temperature of this isotope

float Isotope::getThermalScatteringCutoff ( )

Return the thermal scattering high energy cutoff.

Returns: the thermal scattering high energy cutoff (eV)

float Isotope::getThermalScatteringEnergy ( float energy )

For a given neutron energy (eV) in a scattering collision, this function returns the outgoing energy in eV, $ E' $ , for the collision based on its thermal scattering distributions.

Parameters

energy the energy of the neutron of interest (eV)

Returns: the outgoing energy (eV)

float Isotope::getTotalXS ( float energy ) const

Returns the microscopic total cross-section value for some energy.

Uses linear interpolation to compute the cross-section at a a certain energy (eV).

Parameters

energy the energy (eV) of interest

Returns: the microscopic total cross-section

float Isotope::getTotalXS ( int energy_index ) const

Returns the microscopic total cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data.

Parameters

energy_index the index into the energy array

Returns: the microscopic total cross-section

float Isotope::getTransportXS ( int energy_index ) const

Returns the microscopic transport cross-section value for a certain energy index in this isotope's rescaled uniform lethargy grid of cross-section data.

The transport cross-section corrects for anisotropic scattering using a linear approximation and is computed as follows:

$\sigma_{tr} = \sigma_t - \left<\mu\right>\sigma_s$

Parameters

energy_index the index into the energy array

Returns: the microscopic transport cross-section

float Isotope::getTransportXS ( float energy ) const

Returns the microscopic transport cross-section value for some energy.

Uses linear interpolation to compute the cross-section at a a certain energy (eV). The transport cross-section corrects for anisotropic scattering and is computed as follows:

$\sigma_{tr} = \sigma_t - \left<\mu\right>\sigma_s$

Parameters

energy the energy (eV) of interest

Returns: the microscopic transport cross-section

int Isotope::getUid ( ) const

Returns the unique ID auto-generated for the isotope.

Returns: a unique ID for the isotope

void Isotope::initializeThermalScattering	(	float	start_energy,
		float	end_energy,
		int	num_bins,
		int	num_distributions
	)

private

This method initializes the probability distributions for thermal scattering.

It takes in arguments for the starting energy and end energy (ratios of kT) and the number of distributions which it uses to generate logarithmically spaced energies for the distributions.

Parameters

start_energy	the first distribution's energy (ratio of kT)
end_energy	the final distribution's energy (ratio of kT)
num_bins	the number of bins per distribution
num_distributions	the number of scattering distributions

bool Isotope::isFissionable ( ) const

Return whether this isotope is fissionable (true) or not (false)

Returns: whether this isotope is fissionable

bool Isotope::isRescaled ( ) const

This method returns whether or not the Isotope's cross-sections have been rescaled to a uniform lethargy grid.

Returns: whether or not the cross-sections have been rescaled

void Isotope::loadXS ( )

private

Load the ENDF cross-section data from ASCII files into arrays for this isotope.

This method finds the appropriate ENDF data files for the isotope in the PINSPEC cross-section library based on the user-defined name of the isotope. If the appropriate files are not found the method will return an exception. If only capture and elastic scattering cross-section data files are discovered in the cross-section library then the isotope is not fissionable; otherwise if a fission cross-section file is found then the isotope is fissionable. Finally, after all cross-sections are parsed in from data files, this method computes a total cross-section and an absorption cross-section and then rescales all cross-sections onto a uniform lethargy grid to allow for fast O(1) data lookup.

void Isotope::loadXS ( char * xs_type )

Load the ENDF cross-section data for a particular cross-section from an ASCII file into the appropriate array for this isotope.

This method finds the appropriate ENDF data file for the isotope in the PINSPEC cross-section library based on the user-defined name of the isotope as well as the type of cross-section input ('capture' 'elastic', or 'fission'). If the appropriate file is not found the method will return an exception. Finally, after the cross-section is parsed in from the data file, this method recomputes a total cross-section and an absorption cross-section and then rescales all cross-sections onto a uniform lethargy grid to allow for fast O(1) data lookup.

Parameters

xs_type a character array for the cross-section type

void Isotope::rescaleXS	(	float	start_energy,
		float	end_energy,
		int	num_energies
	)

private

Rescales all of the isotope's cross-sections onto a uniform lethargy grid.

Cross-section rescaling is useful because it allows for a fast O(1) table lookup (and linear interpolation) to compute cross-section values for any given energy.

Parameters

start_energy	the highest lethargy value in the grid
end_energy	the lowest lethargy value in the grid
num_energies	the number of energies represented in the grid

void Isotope::retrieveEprimeToE	(	float *	Eprime_to_E,
		int	num_bins
	)

Loads an input array with the $\frac{E'}{E}$ values for each thermal scattering CDF.

This method is intended to make data available to the PINSPEC user in Python. Although this function appears to require two input arguments, in reality it only requires one argument for the array in Python. This method would be called in Python as follows:

num_bins = isotope.getNumThermalCDFBins()

Eprime_to_E = isotope.retrieveEprimeToE(num_bins)

Parameters

Eprime_to_E	an array of $\frac{E'}{E}$ values
num_bins	the number of bins per thermal scattering CDF

void Isotope::retrieveEtokT	(	float *	E_to_kT,
		int	num_cdfs
	)

Loads an input array with the $\frac{E}{kT}$ values for each thermal scattering CDF.

This method is intended to make data available to the PINSPEC user in Python. Although this function appears to require two input argument, in reality it only requires one argument for the array in Python. This method would be called in Python as follows:

num_cdfs = isotope.getNumThermalCDFs()

E_to_kT = isotope.retrieveEtokT(num_cdfs)

Parameters

E_to_kT	an array of $\frac{E}{kT}$ values
num_cdfs	the number of thermal scattering CDFs

void Isotope::retrieveThermalCDFs	(	float *	cdfs,
		int	num_values
	)

Loads an input array with the values for each of the isotope's thermal CDFs.

This method is intended to make the CDF data available to the PINSPEC user in Python. Although this function appears to require two input arguments - the cdfs array and the length of the array - in reality it only requires one argument for the array in Python. This method would be called in Python as follows:

num_cdfs = isotope.getNumThermalCDFs()
num_bins = isotope.getNumThermalCDFBins()
cdfs = isotope.retrieveThermalCDFs(num_cdfs * num_bins)

Parameters

cdfs	an input array for to fill with CDF values
num_values	the number of CDF bins multiplied by the number of CDFs

void Isotope::retrieveThermalPDFs	(	float *	pdfs,
		int	num_values
	)

Loads an input array with the energies for each of the isotope's thermal PDFs.

This method is intended to make the PDF data available to the PINSPEC user in Python. Although this function appears to require two input arguments - the PDFs array and the length of the array - in reality it only requires one argument for the array in Python. This method would be called in Python as follows:

num_cdfs = isotope.getNumThermalCDFs()
num_bins = isotope.getNumThermalCDFBins()
pdfs = isotope.retrieveThermalDistributions(num_cdfs * num_bins)

Parameters

pdfs	an input array for to fill with CDF values
num_values	the number of CDF bins multiplied by the number of CDFs

void Isotope::retrieveXS	(	float *	xs,
		int	num_xs,
		char *	xs_type
	)		const

Fills an array with microscopic cross-section values.

This method is a helper function to allow PINSPEC users to get access to the isotope's nuclear data in Python. A user must initialize a numpy array of the correct size (ie, a float64 array the length of the number of cross-section values) as input to this function. This function then fills the numpy array with the data values for one of the isotope's cross-sections. An example of how this function might be called in Python is as follows:

num_xs = isotope.getNumXSEnergies()

xs = isotope.retrieveXS(num_energies, 'capture')

Parameters

xs	an array to fill with the microscopic cross-section data
num_xs	the number of cross-section values
xs_type	the type of cross-section

void Isotope::retrieveXSEnergies	(	float *	energies,
		int	num_xs,
		char *	xs_type
	)		const

Fills an array with cross-section energy values.

This method is a helper function to allow PINSPEC users to get access to the isotope's nuclear data in Python. A user must initialize a numpy array of the correct size (ie, a float64 array the length of the number of cross-section values) as input to this function. This function then fills the numpy array with the energy values for the isotope's cross-section data. An example of how this function might be called in Python is as follows:

num_energies = isotope.getNumXSEnergies()

energies = isotope.retrieveXSEnergies(num_energies, 'capture')

Parameters

energies	an array to fill with the cross-section energies
num_xs	the number of cross-section values
xs_type	the type of cross-section

void Isotope::sampleCollisionType ( neutron * neutron )

Determines a random collision type based on the values of each of the isotope's cross-section values at a given enery.

Parameters

neutron a pointer to structure the of interest

void Isotope::setA ( int A )

Set the atomic number and update alpha, eta and rho.

Computes alpha, eta, rho and mu as follows:

$\alpha = \left(\frac{A-1}{A+1}\right)^2$ $\eta = \left(\frac{A+1}{2\sqrt{A}}\right)^2$ $\rho = \left(\frac{A-1}{2\sqrt{A}}\right)^2$

Parameters

A	the isotope's atomic number

void Isotope::setCaptureXS	(	float *	capture_xs,
		float *	capture_xs_energies,
		int	num_capture_xs
	)

private

Set the capture cross-section for this isotope.

Parameters

capture_xs	a float array of microscopic capture cross-sections
capture_xs_energies	a float array of energies (eV)
num_capture_xs	the number of capture cross-section

void Isotope::setCaptureXS	(	double *	energies,
		int	num_energies,
		double *	capture_xs,
		int	num_xs
	)

Sets the capture cross-section data for this isotope.

This is a helper function for users to assign the cross-section data for an isotope from a numpy array in Python. Although the prototype for this function seems to require four arguments - two with arrays of data for energies and cross-sections and two for the length of each array - in Python one must only give the method a handle to each of two arrays. A user may call this method from within Python as follows:

energies = numpy.array([1E-3, 0.1, 1., 10., 1000.])
xs = numpy.array([1000., 1000., 10., 1., 0.1])
isotope.setCaptureXS(energies, xs)

Parameters

energies	an array of energy values
num_energies	the number of data points
capture_xs	the microscopic elastic cross-section values
num_xs	the number of cross-section values

void Isotope::setElasticXS	(	float *	elastic_xs,
		float *	elastic_xs_energies,
		int	num_elastic_xs
	)

private

Set the elastic cross-section for this isotope.

Parameters

elastic_xs	a float array of microscopic elastic cross-sections
elastic_xs_energies	a float array of energies (eV)
num_elastic_xs	the number of elastic cross-section values

void Isotope::setElasticXS	(	double *	energies,
		int	num_energies,
		double *	elastic_xs,
		int	num_xs
	)

Sets the elastic cross-section data for this isotope.

This is a helper function for users to assign the cross-section data for an isotope from a numpy array in Python. Although the prototype for this function seems to require four arguments - two with arrays of data for energies and cross-sections and two for the length of each array - in Python one must only give the method a handle to each of two arrays. A user may call this method from within Python as follows:

energies = numpy.array([1E-3, 0.1, 1., 10., 1000.])
xs = numpy.array([1000., 1000., 10., 1., 0.1])
isotope.setElasticXS(energies, xs)

Parameters

energies	an array of energy values
num_energies	the number of data points
elastic_xs	the microscopic elastic cross-section values
num_xs	the number of cross-section values

void Isotope::setFissionXS	(	float *	fission_xs,
		float *	fission_xs_energies,
		int	num_fission_xs
	)

private

Set the fission cross-section for this isotope.

Parameters

fission_xs	a float array of microscopic fission cross-sections
fission_xs_energies	a float array of energies (eV)
num_fission_xs	the number of fission cross-sections values

void Isotope::setFissionXS	(	double *	energies,
		int	num_energies,
		double *	fission_xs,
		int	num_xs
	)

Sets the fission cross-section data for this isotope.

This is a helper function for users to assign the cross-section data for an isotope from a numpy array in Python. Although the prototype for this function seems to require four arguments - two with arrays of data for energies and cross-sections and two for the length of each array - in Python one must only give the method a handle to each of two arrays. A user may call this method from within Python as follows:

energies = numpy.array([1E-3, 0.1, 1., 10., 1000.])
xs = numpy.array([1000., 1000., 10., 1., 0.1])
isotope.setFissionXS(energies, xs)

Parameters

energies	an array of energy values
num_energies	the number of data points
fission_xs	the microscopic fission cross-section values
num_xs	the number of cross-section values

void Isotope::setMultigroupCaptureXS	(	double *	energies,
		int	num_energies,
		double *	capture_xs,
		int	num_xs
	)

Sets the multigroup capture cross-section data for this isotope.

This is a helper function for users to assign the cross-section data for an isotope from a numpy array in Python. Although the prototype for this function seems to require four arguments - two with arrays of data for energies and cross-sections and two for the length of each array - in Python one must only give the method a handle to each of two arrays. A user may call this method from within Python as follows:

energies = numpy.array([1E-3, 0.1, 1., 10., 1000., 1E7])
xs = numpy.array([1000., 1000., 10., 1., 0.1])
isotope.setMultigroupCaptureXS(energies, xs)

Parameters

energies	an array of energy bounds
num_energies	the number of energy bounds
capture_xs	the microscopic capture multigroup cross-sections
num_xs	the number of multigroup cross-sections

void Isotope::setMultigroupElasticXS	(	double *	energies,
		int	num_energies,
		double *	elastic_xs,
		int	num_xs
	)

Sets the multigroup elastic cross-section data for this isotope.

This is a helper function for users to assign the cross-section data for an isotope from a numpy array in Python. Although the prototype for this function seems to require four arguments - two with arrays of data for energies and cross-sections and two for the length of each array - in Python one must only give the method a handle to each of two arrays. A user may call this method from within Python as follows:

energies = numpy.array([1E-3, 0.1, 1., 10., 1000., 1E7])
xs = numpy.array([1000., 1000., 10., 1., 0.1])
isotope.setMultigroupElasticXS(energies, xs)

Parameters

energies	an array of energy bounds
num_energies	the number of energy bounds
elastic_xs	the microscopic elastic multigroup cross-sections
num_xs	the number of multigroup cross-sections

void Isotope::setMultigroupFissionXS	(	double *	energies,
		int	num_energies,
		double *	fission_xs,
		int	num_xs
	)

Sets the multigroup fission cross-section data for this isotope.

This is a helper function for users to assign the cross-section data for an isotope from a numpy array in Python. Although the prototype for this function seems to require four arguments - two with arrays of data for energies and cross-sections and two for the length of each array - in Python one must only give the method a handle to each of two arrays. A user may call this method from within Python as follows:

energies = numpy.array([1E-3, 0.1, 1., 10., 1000., 1E7])
xs = numpy.array([1000., 1000., 10., 1., 0.1])
isotope.setMultigroupFissionXS(energies, xs)

Parameters

energies	an array of energy bounds
num_energies	the number of energy bounds
fission_xs	the microscopic fission multigroup cross-sections
num_xs	the number of multigroup cross-sections

void Isotope::setTemperature ( float T )

Set the temperature of the isotope in degrees Kelvin.

Parameters

T	the temperature in degrees Kelvin

void Isotope::setThermalScatteringCutoff ( float cutoff_energy )

Sets the thermal scattering high energy cutoff energy.

Parameters

cutoff_energy the thermal scattering high energy cutoff energy (eV)

float Isotope::thermalScatteringProb	(	float	E_prime_to_E,
		int	dist_index
	)

private

This function computes the thermal scattering probability for a ratio of initial to final energies.

Parameters

E_prime_to_E	a ratio of initial to final energies
dist_index	the distribution of interest

Returns: the probability of the ratio occurring

bool Isotope::usesThermalScattering ( )

This method returns true if the thermal scattering distributions for this isotope are to be used when sampling outgoing collision energy.

Returns: boolean if the thermal scattering distributions exist

Member Data Documentation

int Isotope::_A

private

Atomic number

int Isotope::_A_plus_one_squared

private

Atomic number plus one squared (an optimization for speeup): $ (A+1)^2 $

int Isotope::_A_squared

private

Atomic number squared (an optimization for speedup)

float* Isotope::_absorb_xs

private

Array of microscopic absorption cross-section values

float* Isotope::_absorb_xs_energies

private

Array of absorption cross-section energies (eV)

float Isotope::_alpha

private

$\alpha = \left(\frac{A-1}{A+1}\right)^2$

float Isotope::_AO

private

Atomic number ratio

bool Isotope::_capture_rescaled

private

Whether or not the capture cross-section is rescaled onto a uniform lethargy grid

float* Isotope::_capture_xs

private

Array of microscopic capture cross-section values

float* Isotope::_capture_xs_energies

private

Array of capture cross-section energies (eV)

float Isotope::_delta_lethargy

private

Space between lethargies in uniform grid

float* Isotope::_E_to_kT

private

Array of the $\frac{E}{kT}$ values for each PDF/CDF

bool Isotope::_elastic_rescaled

private

Whether or not the elastic scattering cross-section is rescaled onto a uniform lethargy grid

float* Isotope::_elastic_xs

private

Array of microscopic elastic scattering cross-section values

float* Isotope::_elastic_xs_energies

private

Array of elastic scattering cross-section energies (eV)

float Isotope::_end_lethargy

private

Final lethargy for uniform lethargy grid

float* Isotope::_Eprime_to_E

private

Array of $\frac{E}{E'}$ for each PDF/CDF

float Isotope::_eta

private

$\eta = \left(\frac{A+1}{2\sqrt{A}}\right)^2$

bool Isotope::_fission_rescaled

private

Whether or not the fission cross-section is rescaled onto a uniform lethargy grid

float* Isotope::_fission_xs

private

Array of microscopic fission cross-section values

float* Isotope::_fission_xs_energies

private

Array of fission cross-section energies (eV)

bool Isotope::_fissionable

private

Whether isotope is fissionable or not

char* Isotope::_isotope_name

private

The name of the isotope-periodic table name followed by atomic number

float Isotope::_kB

private

Boltzmann's constant

float Isotope::_mu_avg

private

The average cosine of the scattering angle: $\left<\mu\right> = \frac{2}{3A}$

int Isotope::_n = 1

staticprivate

A static class variable to generate a UID for each new isotope

int Isotope::_num_absorb_xs

private

The number of absorption cross-section data points

int Isotope::_num_capture_xs

private

The number of capture cross-section data points

int Isotope::_num_elastic_xs

private

The number of elastic scattering cross-section data points

int Isotope::_num_energies

private

Number of rescaled cross-section values on uniform lethargy grid

int Isotope::_num_fission_xs

private

The number of fission cross-section data points

int Isotope::_num_thermal_cdf_bins

private

The number of bins per thermal scattering CDFs

int Isotope::_num_thermal_cdfs

private

The number of thermal scattering CDFs

int Isotope::_num_total_xs

private

The number of total cross-section data points

bool Isotope::_rescaled

private

Whether cross-sections are rescaled on uniform lethargy grid

float Isotope::_rho

private

$\rho = \left(\frac{A+1}{2\sqrt{A}}\right)$

float Isotope::_start_lethargy

private

Starting lethargy for uniform lethargy grid

float Isotope::_T

private

Temperature of the isotope in degrees Kelvin

float** Isotope::_thermal_cdfs

private

2D array of thermal scattering CDFs

float Isotope::_thermal_cutoff

private

The high energy cutoff for the thermal scattering treatment (eV)

float* Isotope::_thermal_dist

private

The number of thermal scattering PDFs

float* Isotope::_total_xs

private

Array of microscopic total cross-section values

float* Isotope::_total_xs_energies

private

Whether or not the total cross-section is rescaled onto a uniform lethargy grid

int Isotope::_uid

private

The isotope's unique identifier

bool Isotope::_use_thermal_scattering

private

Whether or not to use thermal scattering

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

pinspec/src/Isotope.h
pinspec/src/Isotope.cpp

Public Member Functions

Private Member Functions

Private Attributes

Static Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation