celeritas::XsCalculator Class Reference

Find and interpolate scaled cross sections on a uniform log grid. More...

#include <XsCalculator.hh>

Public Types
Type aliases
using	Energy = Quantity< XsGridData::EnergyUnits >
using	Values = Collection< real_type, Ownership::const_reference, MemSpace::native >

Public Member Functions
CELER_FUNCTION	XsCalculator (XsGridData const &grid, Values const &values)
	Construct from cross section data.
CELER_FUNCTION real_type	operator() (Energy energy) const
	Calculate the cross section. More...
CELER_FUNCTION real_type	operator[] (size_type index) const
	Get the cross section at the given index.
CELER_FUNCTION Energy	energy_min () const
CELER_FUNCTION Energy	energy_max () const

Detailed Description

Find and interpolate scaled cross sections on a uniform log grid.

This cross section calculator uses the same representation and interpolation as Geant4's physics tables for EM physics:

• The energy grid is uniformly spaced in log(E),
• Values greater than or equal to an index i' are scaled by E,
• Linear interpolation between energy points is used to calculate the final value, and
• If the energy is at or above the i' index, the final result is scaled by 1/E.

This scaling and interpolation exactly reproduces functions \( f(E) \sim a E + b \) below the E' threshold and \( f(E) \sim \frac{a'}{E} + b' \) above that threshold.

Note that linear interpolation is applied with energy points, not log-energy points.

XsCalculator calc_xs(xs_grid, xs_params.reals);
real_type xs = calc_xs(particle.energy());

Member Function Documentation

operator()()

CELER_FUNCTION real_type celeritas::XsCalculator::operator() ( Energy  energy ) const

inline

Calculate the cross section.

If needed, we can add a "log(energy/MeV)" accessor if we constantly reuse that value and don't want to repeat the std::log operation.

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

• XsCalculator.hh