Physics data for a track. More...

#include <PhysicsTrackView.hh>

Public Types
Type aliases
using	Initializer_t = PhysicsTrackInitializer

using	PhysicsParamsRef = NativeCRef< PhysicsParamsData >

using	PhysicsStateRef = NativeRef< PhysicsStateData >

using	Energy = units::MevEnergy

using	ModelFinder = GridIdFinder< Energy, ParticleModelId >

Public Member Functions
CELER_FUNCTION	PhysicsTrackView (PhysicsParamsRef const &params, PhysicsStateRef const &states, ParticleId particle, MaterialId material, TrackSlotId tid)
	Construct from shared and state data. More...

CELER_FUNCTION PhysicsTrackView &	operator= (Initializer_t const &)
	Initialize the track view.

CELER_FUNCTION void	interaction_mfp (real_type)
	Set the distance to the next interaction, in mean free paths. More...

CELER_FUNCTION void	reset_interaction_mfp ()
	Set the distance to the next interaction, in mean free paths. More...

CELER_FUNCTION void	dedx_range (real_type)
	Set the energy loss range for the current material and particle energy. More...

CELER_FUNCTION void	msc_range (MscRange const &)
	Set the range properties for multiple scattering. More...

CELER_FORCEINLINE_FUNCTION bool	has_interaction_mfp () const
	Whether the remaining MFP has been calculated.

CELER_FORCEINLINE_FUNCTION real_type	interaction_mfp () const
	Remaining MFP to interaction.

CELER_FORCEINLINE_FUNCTION real_type	dedx_range () const
	Energy loss range.

CELER_FORCEINLINE_FUNCTION MscRange const &	msc_range () const
	Persistent range properties for multiple scattering within a same volume.

CELER_FORCEINLINE_FUNCTION MaterialId	material_id () const
	Current material identifier.

CELER_FUNCTION ParticleProcessId::size_type	num_particle_processes () const
	Number of processes that apply to this track.

CELER_FUNCTION ProcessId	process (ParticleProcessId) const
	Process ID for the given within-particle process index.

CELER_FUNCTION ValueGridId	value_grid (ValueGridType table, ParticleProcessId) const
	Return value grid data for the given table type and process if available. More...

CELER_FUNCTION IntegralXsProcess const &	integral_xs_process (ParticleProcessId ppid) const
	Get data for processes that use the integral approach. More...

CELER_FUNCTION real_type	calc_xs (ParticleProcessId ppid, MaterialView const &material, Energy energy) const
	Calculate macroscopic cross section for the process.

CELER_FUNCTION real_type	calc_max_xs (IntegralXsProcess const &process, ParticleProcessId ppid, MaterialView const &material, Energy energy) const
	Estimate maximum macroscopic cross section for the process over the step. More...

CELER_FUNCTION ModelFinder	make_model_finder (ParticleProcessId) const
	Models that apply to the given process ID.

CELER_FUNCTION ValueTableId	value_table (ParticleModelId) const
	Return value table data for the given particle/model/material. More...

CELER_FUNCTION TabulatedElementSelector	make_element_selector (ValueTableId, Energy) const
	Construct an element selector to sample an element from tabulated xs data.

CELER_FUNCTION bool	has_at_rest () const
	Whether the particle can have a discrete interaction at rest.

CELER_FUNCTION ModelId	action_to_model (ActionId) const
	Convert an action to a model ID for diagnostics, false if not a model.

CELER_FUNCTION ActionId	model_to_action (ModelId) const
	Convert a selected model ID into a simulation action ID.

CELER_FUNCTION ModelId	model_id (ParticleModelId) const
	Get the model ID corresponding to the given ParticleModelId.

CELER_FUNCTION real_type	range_to_step (real_type range) const
	Calculate scaled step range. More...

CELER_FORCEINLINE_FUNCTION PhysicsParamsScalars const &	scalars () const
	Access scalar properties (options, IDs).

CELER_FUNCTION size_type	num_particles () const
	Number of particle types.

template<class T >
CELER_FUNCTION T	make_calculator (ValueGridId) const
	Construct a grid calculator of the given type. More...

CELER_FUNCTION ModelId	hardwired_model (ParticleProcessId ppid, Energy energy) const
	Return the model ID that applies to the given process ID and energy if the process is hardwired to calculate macroscopic cross sections on the fly. More...

CELER_FUNCTION ParticleProcessId	eloss_ppid () const
	Particle-process ID of the process with the de/dx and range tables.

Detailed Description

Physics data for a track.

The physics track view provides an interface for data and operations common to most processes and models.

Constructor & Destructor Documentation

◆ PhysicsTrackView()

CELER_FUNCTION celeritas::PhysicsTrackView::PhysicsTrackView	(	PhysicsParamsRef const &	params,
		PhysicsStateRef const &	states,
		ParticleId	pid,
		MaterialId	mid,
		TrackSlotId	tid
	)

inline

Construct from shared and state data.

Particle and material IDs are derived from other class states.

Member Function Documentation

◆ calc_max_xs()

CELER_FUNCTION real_type celeritas::PhysicsTrackView::calc_max_xs	(	IntegralXsProcess const &	process,
		ParticleProcessId	ppid,
		MaterialView const &	material,
		Energy	energy
	)		const

inline

Estimate maximum macroscopic cross section for the process over the step.

If this is a particle with an energy loss process, this returns the estimate of the maximum cross section over the step. If the energy of the global maximum of the cross section (calculated at initialization) is in the interval \( [\xi E_0, E_0) \), where \( E_0 \) is the pre-step energy and \( \xi \) is min_eprime_over_e (defined by default as \( \xi = 1 - \alpha \), where \( \alpha \) is max_step_over_range), \( \sigma_{\max} \) is set to the global maximum. Otherwise, \( \sigma_{\max} = \max( \sigma(E_0), \sigma(\xi E_0) ) \). If the cross section is not monotonic in the interval \( [\xi E_0, E_0) \) and the interval does not contain the global maximum, the post-step cross section \( \sigma(E_1) \) may be larger than \( \sigma_{\max} \).

◆ dedx_range()

CELER_FUNCTION void celeritas::PhysicsTrackView::dedx_range ( real_type range )

inline

Set the energy loss range for the current material and particle energy.

This value will be calculated once at the beginning of each step.

◆ hardwired_model()

CELER_FUNCTION ModelId celeritas::PhysicsTrackView::hardwired_model	(	ParticleProcessId	ppid,
		Energy	energy
	)		const

inline

Return the model ID that applies to the given process ID and energy if the process is hardwired to calculate macroscopic cross sections on the fly.

If the result is null, tables should be used for this process/energy.

◆ integral_xs_process()

CELER_FUNCTION auto celeritas::PhysicsTrackView::integral_xs_process ( ParticleProcessId ppid ) const

inline

Get data for processes that use the integral approach.

Particles that have energy loss processes will have a different energy at the pre- and post-step points. This means the assumption that the cross section is constant along the step is no longer valid. Instead, Monte Carlo integration can be used to sample the interaction length for the discrete process with the correct probability from the exact distribution,

\[ p = 1 - \exp \left( -\int_{E_0}^{E_1} n \sigma(E) \dif s \right), \]

where \( E_0 \) is the pre-step energy, \( E_1 \) is the post-step energy, n is the atom density, and s is the interaction length.

At the start of the step, the maximum value of the cross section over the step \( \sigma_{max} \) is estimated and used as the macroscopic cross section for the process rather than \( \sigma_{E_0} \). After the step, the new value of the cross section \( \sigma(E_1) \) is calculated, and the discrete interaction for the process occurs with probability

\[ p = \frac{\sigma(E_1)}{\sigma_{\max}}. \]

See section 7.4 of the Geant4 Physics Reference (release 10.6) for details.

◆ interaction_mfp()

CELER_FUNCTION void celeritas::PhysicsTrackView::interaction_mfp ( real_type mfp )

inline

Set the distance to the next interaction, in mean free paths.

This value will be decremented at each step.

◆ make_calculator()

template<class T >

CELER_FUNCTION T celeritas::PhysicsTrackView::make_calculator ( ValueGridId id ) const

inline

Construct a grid calculator of the given type.

The calculator must take two arguments: a reference to XsGridRef, and a reference to the Values data structure.

◆ msc_range()

CELER_FUNCTION void celeritas::PhysicsTrackView::msc_range ( MscRange const & msc_range )

inline

Set the range properties for multiple scattering.

These values will be calculated at the first step in every tracking volume.

◆ range_to_step()

CELER_FUNCTION real_type celeritas::PhysicsTrackView::range_to_step ( real_type range ) const

inline

Calculate scaled step range.

This is the updated step function given by Eq. 7.4 of Geant4 Physics Reference Manual, Release 10.6:

\[ s = \alpha r + \rho (1 - \alpha) (2 - \frac{\rho}{r}) \]

where alpha is max_step_over_range and rho is min_range .

Below min_range, no step scaling is applied, but the step can still be arbitrarily small.

◆ reset_interaction_mfp()

CELER_FUNCTION void celeritas::PhysicsTrackView::reset_interaction_mfp ( )

inline

Set the distance to the next interaction, in mean free paths.

This value will be decremented at each step.

◆ value_grid()

CELER_FUNCTION auto celeritas::PhysicsTrackView::value_grid	(	ValueGridType	table_type,
		ParticleProcessId	ppid
	)		const

inline

Return value grid data for the given table type and process if available.

If the result is not null, it can be used to instantiate a grid Calculator.

If the result is null, it's likely because the process doesn't have the associated value (e.g. if the table type is "energy_loss" and the process is not a slowing-down process).

◆ value_table()

CELER_FUNCTION ValueTableId celeritas::PhysicsTrackView::value_table ( ParticleModelId pmid ) const

inline

Return value table data for the given particle/model/material.

A null result means either the model is material independent or the material only has one element, so no cross section CDF tables are stored.

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

PhysicsTrackView.hh

Public Types

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ PhysicsTrackView()

Member Function Documentation

◆ calc_max_xs()

◆ dedx_range()

◆ hardwired_model()

◆ integral_xs_process()

◆ interaction_mfp()

◆ make_calculator()

◆ msc_range()

◆ range_to_step()

◆ reset_interaction_mfp()

◆ value_grid()

◆ value_table()