celeritas::TsaiUrbanDistribution Class Reference

Sample exiting polar angle for pair production and bremsstrahlung. More...

#include <TsaiUrbanDistribution.hh>

Public Types
Type aliases
using	Energy = units::MevEnergy
using	Mass = units::MevMass
using	result_type = real_type

Public Member Functions
CELER_FUNCTION	TsaiUrbanDistribution (Energy energy, Mass mass)
	Construct from input data.
template<class Engine >
CELER_FUNCTION result_type	operator() (Engine &rng)
template<class Engine >
CELER_FUNCTION real_type	operator() (Engine &rng)
	Sample the cosine of the polar angle of the exiting gamma.

Detailed Description

Sample exiting polar angle for pair production and bremsstrahlung.

For pair production, the polar angle of the electron (or positron) is defined with respect to the direction of the parent photon. The energy- angle distribution given by Tsai is quite complicated to sample and can be approximated by a density function suggested by Urban.

The angular distribution of the emitted photons is obtained from a simplified formula based on the Tsai cross-section, which is expected to become isotropic in the low energy limit.

The sample result is the cosine of the exiting angle with respect to the incident angle.

Note

This performs the same sampling routine as in Geant4's ModifiedTsai class, based on derivation from [tsai-1974] and documented in section 6.5.2 (pair-production), and 10.2.1 and 10.2.4 (bremsstrahlung) of the Geant4 Physics Reference [g4prm] (release 10.6).

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

• TsaiUrbanDistribution.hh