Class MultiGroupXS

Nested Relationships

Nested Types

Class Documentation

class MultiGroupXS

Public Functions

inline MultiGroupXS()
void Scale(double factor)

Scale the cross sections by the specified factor.

Note

Scaling factors do not compound. Each time this routine is called, the cross sections are scaled from the original, unscaled data.

inline double GetScaleFactor() const
void ExportToOpenSnXSFile(const std::string &file_name, double fission_scaling = 1.0) const

Exports the cross-section information to OpenSn format.

Parameters:

  • file_name – The name of the file to save the cross sections to.

  • fission_scaling – A factor to scale fission data to. This is generally equal to \( 1/k_{eff} \). Generally, this is done to create exactly critical cross sections for a transient initial condition.

inline unsigned int GetNumGroups() const
inline unsigned int GetScatteringOrder() const
inline unsigned int GetNumPrecursors() const
inline bool IsFissionable() const
inline void SetAdjointMode(bool val)
inline bool GetAdjointMode() const
inline const std::vector<double> &GetSigmaTotal() const
inline const std::vector<double> &GetSigmaAbsorption() const
inline const std::vector<double> &GetEnergyDeposition() const
inline const std::vector<double> &GetStoppingPower() const
inline const std::vector<ParticleType> &GetParticleTypes() const
std::vector<std::pair<unsigned int, unsigned int>> GetStoppingPowerGroupRanges() const

Returns contiguous half-open ranges of groups with nonzero stopping power.

inline const std::vector<SparseMatrix> &GetTransferMatrices() const
inline const SparseMatrix &GetTransferMatrix(unsigned int ell) const
inline const std::vector<double> &GetChi() const
inline const std::vector<double> &GetSigmaFission() const
inline const std::vector<double> &GetNuSigmaF() const
inline const std::vector<double> &GetNuPromptSigmaF() const
inline const std::vector<double> &GetNuDelayedSigmaF() const
inline const std::vector<std::vector<double>> &GetProductionMatrix() const

Note

The LBS source and fission-production routines assume this matrix represents prompt production when delayed-neutrons are enabled, and add delayed production from nu_delayed_sigma_f separately. If production_matrix_ ever includes delayed contributions, those routines must be updated to avoid double counting.

inline const std::vector<Precursor> &GetPrecursors() const
inline const std::vector<double> &GetInverseVelocity() const
inline bool DiffusionInitialized() const
inline const std::vector<double> &GetSigmaTransport() const
inline const std::vector<double> &GetDiffusionCoefficient() const
inline const std::vector<double> &GetSigmaRemoval() const
inline const std::vector<double> &GetSigmaSGtoG() const
std::vector<double> GetDeltaE() const
inline bool HasEnergyGroupBounds() const

Returns true when a complete energy group structure is available.

std::pair<double, double> GetEnergyGroupBounds(unsigned int g) const

Returns the upper and lower energy bounds of group g in the imported energy units.

This accounts for the shared maximum energy at CEPXS particle-species transitions. Throws std::out_of_range if group bounds are unavailable or g is out of range.

std::vector<double> ComputeCollisionEnergyLossCoefficients(const EnergyGroupStructure &energy) const

Computes the per-group collision energy-loss coefficients for this material.

bool HasCustomXS(const std::string &name) const
const std::vector<double> &GetCustomXS(const std::string &name) const
std::vector<std::string> GetCustomXSNames() const
const std::vector<double> *GetByName(const std::string &xs_name) const

Public Static Functions

static EnergyGroupStructure ResolveEnergyGroupStructure(const std::map<unsigned int, std::shared_ptr<MultiGroupXS>> &xs_map, unsigned int num_groups)

Resolves one energy group structure from a collection of material cross sections.

Materials may omit their group structure, but all supplied structures must have identical per-group bounds. At least one complete structure is required.

static MultiGroupXS CreateSimpleOneGroup(double sigma_t, double c, double velocity = 0.0)

Makes a simple material with a 1-group cross-section set.

static MultiGroupXS LoadFromOpenSn(const std::string &filename)
static MultiGroupXS LoadFromCEPXS(const std::string &filename, int material_id = 0, bool csda_format = false, const std::vector<std::string> &particle_order = {})

Loads multi-group cross sections from a CEPXS-BFP binary file.

Parameters:

  • filename – Path to the CEPXS-BFP binary file.

  • material_id – Zero-based index of the material to read from the file.

  • csda_format – When true, reads the CSDA row layout produced by the modified CEPXS, which adds stopping power and requires physical energy group bounds. When false, reads the standard CEPXS row layout and imports no stopping power.

  • particle_order – Optional particle species for each energy block, in BXSLIB order. Accepted values are photon, electron, and positron, with at most one block of each type. When omitted for CSDA data, a single block with nonzero stopping power is inferred as electrons. A single zero-stopping-power block remains unknown so that void materials can inherit the species from other materials. Multi-block CSDA libraries require this argument.

static MultiGroupXS LoadFromOpenMC(const std::string &file_name, const std::string &dataset_name, double temperature, const std::vector<std::string> &extra_xs_names = {})

This method populates transport cross sections from an OpenMC cross-section file.

static MultiGroupXS Combine(const std::vector<std::pair<std::shared_ptr<MultiGroupXS>, double>> &combinations)

Populates the cross section from a combination of others.

Public Static Attributes

static double STOPPING_POWER_TOLERANCE = 1.0e-12
struct Precursor

A struct containing data for a delayed neutron precursor.

Public Members

double decay_constant = 0.0
double fractional_yield = 0.0
std::vector<double> emission_spectrum