Template Class ImpactPointEstimator

Nested Relationships

Class Documentation

template<typename input_track_t, typename propagator_t, typename propagator_options_t = PropagatorOptions<>>
class Acts::ImpactPointEstimator

Estimator for impact point calculations.

Public Functions

ImpactPointEstimator(const Config &cfg)

Constructor.

Parameters

  • cfg: Configuration object

Result<double> calculate3dDistance(const GeometryContext &gctx, const BoundParameters &trkParams, const Vector3D &vtxPos) const

Calculates 3D distance between a track and a 3D point.

Return

Distance

Parameters

  • gctx: The geometry context

  • trkParams: Track parameters

  • vtxPos: Position to calculate distance to

Result<std::unique_ptr<const BoundParameters>> estimate3DImpactParameters(const GeometryContext &gctx, const Acts::MagneticFieldContext &mctx, const BoundParameters &trkParams, const Vector3D &vtxPos) const

Creates track parameters bound to plane at point of closest approach in 3d to given reference position.

The parameters and errors are defined on the plane intersecting the track at point of closest approach, with track orthogonal to the plane and center of the plane defined as the given reference point (vertex).

Return

New track params

Parameters

  • gctx: The geometry context

  • mctx: The magnetic field context

  • trkParams: Track parameters

  • vtxPos: Reference position (vertex)

Result<ImpactParametersAndSigma> estimateImpactParameters(const BoundParameters &track, const Vertex<input_track_t> &vtx, const GeometryContext &gctx, const MagneticFieldContext &mctx) const

Estimates the impact parameters and their errors of a given track w.r.t.

a vertex by propagating the trajectory state towards the vertex position.

Parameters

  • track: Track to estimate IP from

  • vtx: Vertex the track belongs to

  • gctx: The geometry context

  • mctx: The magnetic field context

Result<double> get3dVertexCompatibility(const GeometryContext &gctx, const BoundParameters *trkParams, const Vector3D &vertexPos) const

Estimates the compatibility of a track to a vertex position based on the 3d distance between the track and the vertex.

Return

The compatibility value

Parameters

  • gctx: The Geometry context

  • track: Track parameters at point of closest approach in 3d as retrieved by estimate3DImpactParameters

  • vertexPos: The vertex position

struct Config

Public Functions

Config(const BField_t &bIn, std::shared_ptr<propagator_t> prop)

Config constructor if magnetic field is present.

Parameters

  • bIn: The magnetic field

  • prop: The propagator

template<typename T = BField_t, std::enable_if_t<std::is_same<T, NullBField>::value, int> = 0>
Config(std::shared_ptr<propagator_t> prop)

Config constructor if BField_t == NullBField (no B-Field provided)

Parameters

  • prop: The propagator

Public Members

BField_t bField

Magnetic field.

int maxIterations = 20

Max. number of iterations in Newton method.

double maxRho = 1e+15

Maximum curvature value.

double minQoP = 1e-15

Minimum q/p value.

double precision = 1.e-10

Desired precision in deltaPhi in Newton method.

std::shared_ptr<propagator_t> propagator

Propagator.