Estimate track parameters from seed

Detailed Description

The implemented method is based on the conformal map transformation.

It estimates the full free track parameters, i.e. (x, y, z, t, dx, dy, dz, q/p) at the bottom space point. The magnetic field (which can be along any direction) is also necessary for the momentum estimation.

It resembles the method used in ATLAS for the track parameters estimated from seed, i.e. the function InDet::SiTrackMaker_xk::getAtaPlane here: https://acode-browser.usatlas.bnl.gov/lxr/source/athena/InnerGeometry/InDetRecTools/SiTrackMakerTool_xk/src/SiTrackMaker_xk.cxx

Classes
struct	Acts::EstimateTrackParamCovarianceConfig
	Configuration for the estimation of the covariance matrix of the track parameters with estimateTrackParamCovariance. More...

Functions
BoundMatrix	Acts::estimateTrackParamCovariance (const EstimateTrackParamCovarianceConfig &config, const BoundVector &params, bool hasTime)
	Estimate the covariance matrix of the given track parameters based on the provided configuration.
Result< BoundVector >	Acts::estimateTrackParamsFromSeed (const GeometryContext &gctx, const Surface &surface, const Vector3 &sp0, double t0, const Vector3 &sp1, const Vector3 &sp2, const Vector3 &bField)
	Estimate bound track parameters from three space points.
template<std::ranges::range space_point_range_t>
Result< BoundVector >	Acts::estimateTrackParamsFromSeed (const GeometryContext &gctx, space_point_range_t spRange, const Surface &surface, const Vector3 &bField)
	Estimate bound track parameters from three space points.
FreeVector	Acts::estimateTrackParamsFromSeed (const Vector3 &sp0, const Vector3 &sp1, const Vector3 &sp2, const Vector3 &bField)
	Estimate free track parameters from three space points.
FreeVector	Acts::estimateTrackParamsFromSeed (const Vector3 &sp0, double t0, const Vector3 &sp1, const Vector3 &sp2, const Vector3 &bField)
	Estimate free track parameters from three space points.
template<std::ranges::range space_point_range_t>
FreeVector	Acts::estimateTrackParamsFromSeed (space_point_range_t spRange, const Vector3 &bField)
	Estimate free track parameters from three space points.

Function Documentation

estimateTrackParamCovariance()

BoundMatrix Acts::estimateTrackParamCovariance	(	const EstimateTrackParamCovarianceConfig &	config,
		const BoundVector &	params,
		bool	hasTime )

Estimate the covariance matrix of the given track parameters based on the provided configuration.

The assumption is that we can model the uncertainty of the track parameters as a diagonal matrix with the provided initial sigmas. The inflation factors are used to inflate the initial variances based on the provided configuration. The uncertainty of q/p is estimated based on the relative uncertainty of the q/pt and the theta uncertainty.

Parameters

config	is the configuration for the estimation
params	is the track parameters
hasTime	is true if the track parameters have time

Returns

the covariance matrix of the track parameters

estimateTrackParamsFromSeed() [1/5]

Result< BoundVector > Acts::estimateTrackParamsFromSeed	(	const GeometryContext &	gctx,
		const Surface &	surface,
		const Vector3 &	sp0,
		double	t0,
		const Vector3 &	sp1,
		const Vector3 &	sp2,
		const Vector3 &	bField )

Estimate bound track parameters from three space points.

Parameters

gctx	is the geometry context
surface	is the surface of the bottom space point. The estimated bound track parameters will be represented at this surface.
sp0	is the bottom space point
t0	is the time of the bottom space point
sp1	is the middle space point
sp2	is the top space point
bField	is the magnetic field vector

Returns

bound parameters

estimateTrackParamsFromSeed() [2/5]

template<std::ranges::range space_point_range_t>

Result< BoundVector > Acts::estimateTrackParamsFromSeed	(	const GeometryContext &	gctx,
		space_point_range_t	spRange,
		const Surface &	surface,
		const Vector3 &	bField )

Estimate bound track parameters from three space points.

Template Parameters

space_point_range_t

The type of space point range

Parameters

gctx	is the geometry context
spRange	is the range of space points
surface	is the surface of the bottom space point. The estimated bound track parameters will be represented at this surface.
bField	is the magnetic field vector

Returns

bound parameters

estimateTrackParamsFromSeed() [3/5]

FreeVector Acts::estimateTrackParamsFromSeed	(	const Vector3 &	sp0,
		const Vector3 &	sp1,
		const Vector3 &	sp2,
		const Vector3 &	bField )

Estimate free track parameters from three space points.

This is a purely spatial estimation, i.e. the time parameter will be set to 0.

Parameters

sp0	is the bottom space point
sp1	is the middle space point
sp2	is the top space point
bField	is the magnetic field vector

Returns

the free parameters

estimateTrackParamsFromSeed() [4/5]

FreeVector Acts::estimateTrackParamsFromSeed	(	const Vector3 &	sp0,
		double	t0,
		const Vector3 &	sp1,
		const Vector3 &	sp2,
		const Vector3 &	bField )

Estimate free track parameters from three space points.

Parameters

sp0	is the bottom space point
t0	is the time of the bottom space point
sp1	is the middle space point
sp2	is the top space point
bField	is the magnetic field vector

Returns

the free parameters

estimateTrackParamsFromSeed() [5/5]

template<std::ranges::range space_point_range_t>

FreeVector Acts::estimateTrackParamsFromSeed	(	space_point_range_t	spRange,
		const Vector3 &	bField )

Estimate free track parameters from three space points.

Template Parameters

space_point_range_t

The type of space point range

Parameters

spRange	is the range of space points
bField	is the magnetic field vector

Returns

the free parameters