celeritas::FieldPropagator< SubstepperT, GTV > Class Template Reference

Propagate a charged particle in a field. More...

#include <FieldPropagator.hh>

Public Types
Type aliases
using	result_type = Propagation

Public Member Functions
CELER_FUNCTION	FieldPropagator (SubstepperT &&advance, ParticleTrackView const &particle, GTV &&geo)
	Construct with shared field parameters and the field driver.
CELER_FUNCTION result_type	operator() ()
	Propagate a charged particle until it hits a boundary.
CELER_FUNCTION result_type	operator() (real_type dist)
	Propagate a charged particle in a field.
CELER_FUNCTION short int	max_substeps () const
	Limit on substeps.
CELER_FUNCTION real_type	delta_intersection () const
	Distance close enough to a boundary to mark as being on the boundary.
CELER_FUNCTION real_type	bump_distance () const
	Distance to bump or to consider a "zero" movement.
CELER_FUNCTION real_type	minimum_substep () const
	Distance to bump or to consider a "zero" movement.

Static Public Member Functions
static CELER_CONSTEXPR_FUNCTION bool	tracks_can_loop ()
	Whether it's possible to have tracks that are looping.

Detailed Description

template<class SubstepperT, class GTV>
class celeritas::FieldPropagator< SubstepperT, GTV >

Propagate a charged particle in a field.

For a given initial state (position, momentum), it propagates a charged particle along a curved trajectory up to an interaction length proposed by a chosen physics process for the step, possibly integrating sub-steps by an adaptive step control with a required accuracy of tracking in a field. It updates the final state (position, momentum, boundary) along with the step actually taken. If the final position is outside the current volume, it returns a geometry limited step and the state at the intersection between the curve trajectory and the first volume boundary using an iterative step control method within a tolerance error imposed on the closest distance between two positions by the field stepper and the linear projection to the volume boundary.

Note

This follows similar methods to Geant4's G4PropagatorInField class.

Member Function Documentation

delta_intersection()

template<class SubstepperT , class GTV >

CELER_FUNCTION real_type celeritas::FieldPropagator< SubstepperT, GTV >::delta_intersection ( ) const

inline

Distance close enough to a boundary to mark as being on the boundary.

TODO: change delta intersection from property in FieldDriverOptions to another FieldPropagatorOptions

max_substeps()

template<class SubstepperT , class GTV >

CELER_FUNCTION short int celeritas::FieldPropagator< SubstepperT, GTV >::max_substeps ( ) const

inline

Limit on substeps.

Maximum number of substeps.

operator()()

template<class SubstepperT , class GTV >

CELER_FUNCTION auto celeritas::FieldPropagator< SubstepperT, GTV >::operator() ( real_type  step )

inline

Propagate a charged particle in a field.

It utilises a field driver (based on an adaptive step control to limit the length traveled based on the magnetic field behavior and geometric tolerances) to track a charged particle along a curved trajectory for a given step length within a required accuracy or intersects with a new volume (geometry limited step).

The position of the internal OdeState state_ should be consistent with the geometry geo_'s position, but the geometry's direction will be a series of "trial" directions that are the chords between the start and end points of a curved substep through the field. At the end of the propagation step, the geometry state's direction is updated based on the actual value of the calculated momentum.

Caveats:

• The physical (geometry track state) position may deviate from the exact curved propagation position up to a driver-based tolerance at every boundary crossing. The momentum will always be conserved, though.
• In some unusual cases (e.g. a very small caller-requested step, or an unusual accumulation in the driver's substeps) the distance returned may be slightly higher (again, up to a driver-based tolerance) than the physical distance travelled.

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

• FieldPropagator.hh