#include <acts/blob/sPHENIX/Core/include/Acts/Utilities/SpacePointUtility.hpp>

Collaboration diagram for Acts::SpacePointUtility:

Public Member Functions
	SpacePointUtility (SpacePointBuilderConfig cfg)
	Constructor.

std::pair< Vector3, Vector2 >	globalCoords (const GeometryContext &gctx, const SourceLink &slink, const SourceLinkSurfaceAccessor &surfaceAccessor, const BoundVector &par, const BoundSquareMatrix &cov) const
	Getter method for the global coordinates of a SourceLink.

Vector2	rhoZCovariance (const GeometryContext &gctx, const Surface &surface, const Vector3 &globalPos, const SquareMatrix2 &localCov) const
	Get rho and z covariance from the local position and covariance.

Vector2	calcRhoZVars (const GeometryContext &gctx, const SourceLink &slinkFront, const SourceLink &slinkBack, const SourceLinkSurfaceAccessor &surfaceAccessor, const std::function< std::pair< const BoundVector, const BoundSquareMatrix >(SourceLink)> &paramCovAccessor, const Vector3 &globalPos, const double theta) const
	Calculate the rho and z covariance from the front and back SourceLink in the strip SP formation.

Result< void >	calculateStripSPPosition (const std::pair< Vector3, Vector3 > &stripEnds1, const std::pair< Vector3, Vector3 > &stripEnds2, const Vector3 &posVertex, SpacePointParameters &spParams, const double stripLengthTolerance) const
	This function performs a straight forward calculation of a space point and returns whether it was successful or not.

Result< void >	recoverSpacePoint (SpacePointParameters &spParams, double stripLengthGapTolerance) const
	This function tests if a space point can be estimated by a more tolerant treatment of construction. In fact, this function indirectly allows shifts of the vertex.

Result< double >	differenceOfMeasurementsChecked (const Vector3 &pos1, const Vector3 &pos2, const Vector3 &posVertex, const double maxDistance, const double maxAngleTheta2, const double maxAnglePhi2) const
	Calculates (Delta theta)^2 + (Delta phi)^2 between two SourceLinks.

Result< double >	calcPerpendicularProjection (const std::pair< Vector3, Vector3 > &stripEnds1, const std::pair< Vector3, Vector3 > &stripEnds2, SpacePointParameters &spParams) const
	Calculates a space point without using the vertex.

Private Attributes
SpacePointBuilderConfig	m_config

std::error_code	m_error

Detailed Description

Definition at line 63 of file SpacePointUtility.hpp.

View newest version in sPHENIX GitHub at line 63 of file SpacePointUtility.hpp

Constructor & Destructor Documentation

Acts::SpacePointUtility::SpacePointUtility ( SpacePointBuilderConfig cfg )

inline

Constructor.

Definition at line 66 of file SpacePointUtility.hpp.

View newest version in sPHENIX GitHub at line 66 of file SpacePointUtility.hpp

Member Function Documentation

Result< double > Acts::SpacePointUtility::calcPerpendicularProjection	(	const std::pair< Vector3, Vector3 > &	stripEnds1,
		const std::pair< Vector3, Vector3 > &	stripEnds2,
		SpacePointParameters &	spParams
	)		const

Calculates a space point without using the vertex.

Note: This is mostly to resolve space points from cosmic data

Parameters

stripEnds1	The ends of one strip
stripEnds2	The ends of another strip
spParams	SpacePointParamaters for the SP

Returns

parameter that indicates the location of the space point; returns

if it failed

Note: The meaning of the parameter is explained in more detail in the function body

This approach assumes that no vertex is available. This option aims to approximate the space points from cosmic data. The underlying assumption is that the best point is given by the closest distance between both lines describing the SDEs. The point x on the first SDE is parametrized as a + lambda0 * q with the top end a of the strip and the vector q = a - b(ottom end of the strip). An analogous parametrization is performed of the second SDE with y = c + lambda1 * r. x get resolved by resolving lambda0 from the condition that |x-y| is the shortest distance between two skew lines.

Definition at line 290 of file SpacePointUtility.cpp.

View newest version in sPHENIX GitHub at line 290 of file SpacePointUtility.cpp

References ac(), Acts::UnitConstants::e, Acts::SpacePointParameters::firstBtmToTop, m_error, and Acts::SpacePointParameters::secondBtmToTop.

Here is the call graph for this function:

Vector2 Acts::SpacePointUtility::calcRhoZVars	(	const GeometryContext &	gctx,
		const SourceLink &	slinkFront,
		const SourceLink &	slinkBack,
		const SourceLinkSurfaceAccessor &	surfaceAccessor,
		const std::function< std::pair< const BoundVector, const BoundSquareMatrix >(SourceLink)> &	paramCovAccessor,
		const Vector3 &	globalPos,
		const double	theta
	)		const

Calculate the rho and z covariance from the front and back SourceLink in the strip SP formation.

Parameters

gctx	The current geometry context object, e.g. alignment
slinkFront	The SourceLink on the front layer
slinkBack	The SourceLink on the back layer
paramCovAccessor	function to extract local position and covariance from SourceLink
surfaceAccessor	function to extract surface from SourceLink
globalPos	global position
theta	The angle between the two strips

Returns: (rho, z) components of the global covariance

Definition at line 90 of file SpacePointUtility.cpp.

View newest version in sPHENIX GitHub at line 90 of file SpacePointUtility.cpp

References rhoZCovariance(), and writeMapConfig::surface.

Here is the call graph for this function:

Result< void > Acts::SpacePointUtility::calculateStripSPPosition	(	const std::pair< Vector3, Vector3 > &	stripEnds1,
		const std::pair< Vector3, Vector3 > &	stripEnds2,
		const Vector3 &	posVertex,
		SpacePointParameters &	spParams,
		const double	stripLengthTolerance
	)		const

This function performs a straight forward calculation of a space point and returns whether it was successful or not.

Parameters

[in]	stripEnds1	Top and bottom end of the first strip
[in]	stripEnds2	Top and bottom end of the second strip
[in]	posVertex	Position of the vertex
[in,out]	spParams	Data container of the calculations
[in]	stripLengthTolerance	Tolerance scaling factor on the strip detector element length

Returns: Result whether the space point calculation was successful

The following algorithm is meant for finding the position on the first strip if there is a corresponding Measurement on the second strip. The resulting point is a point x on the first surfaces. This point is along a line between the points a (top end of the strip) and b (bottom end of the strip). The location can be parametrized as 2 * x = (1 + m) a + (1 - m) b as function of the scalar m. m is a parameter in the interval -1 < m < 1 since the hit was on the strip. Furthermore, the vector from the vertex to the Measurement on the second strip y is needed to be a multiple k of the vector from vertex to the hit on the first strip x. As a consequence of this demand y = k * x needs to be on the connecting line between the top (c) and bottom (d) end of the second strip. If both measurements correspond to each other, the condition y * (c X d) = k * x (c X d) = 0 ("X" represents a cross product) needs to be fulfilled. Inserting the first equation into this equation leads to the condition for m as given in the following algorithm and therefore to the calculation of x. The same calculation can be repeated for y. Its corresponding parameter will be named n.

Definition at line 143 of file SpacePointUtility.cpp.

View newest version in sPHENIX GitHub at line 143 of file SpacePointUtility.cpp

References Acts::SpacePointParameters::firstBtmToTop, Acts::SpacePointParameters::firstBtmToTopXvtxToFirstMid2, Acts::SpacePointParameters::limit, Acts::SpacePointParameters::m, m_error, Acts::SpacePointParameters::n, Acts::SpacePointParameters::secondBtmToTop, Acts::SpacePointParameters::secondBtmToTopXvtxToSecondMid2, Acts::SpacePointParameters::vtxToFirstMid2, and Acts::SpacePointParameters::vtxToSecondMid2.

Result< double > Acts::SpacePointUtility::differenceOfMeasurementsChecked	(	const Vector3 &	pos1,
		const Vector3 &	pos2,
		const Vector3 &	posVertex,
		const double	maxDistance,
		const double	maxAngleTheta2,
		const double	maxAnglePhi2
	)		const

Calculates (Delta theta)^2 + (Delta phi)^2 between two SourceLinks.

Parameters

[in]	pos1	position of the first SourceLink
[in]	pos2	position the second SourceLink
[in]	posVertex	Position of the vertex
[in]	maxDistance	Maximum distance between two SourceLinks
[in]	maxAngleTheta2	Maximum squared theta angle between two SourceLinks
[in]	maxAnglePhi2	Maximum squared phi angle between two SourceLinks

Returns: Result with the squared sum within configuration parameters.

Definition at line 23 of file SpacePointUtility.cpp.

View newest version in sPHENIX GitHub at line 23 of file SpacePointUtility.cpp

References m_error, norm, Acts::VectorHelpers::phi(), and Acts::VectorHelpers::theta().

Here is the call graph for this function:

std::pair< Vector3, Vector2 > Acts::SpacePointUtility::globalCoords	(	const GeometryContext &	gctx,
		const SourceLink &	slink,
		const SourceLinkSurfaceAccessor &	surfaceAccessor,
		const BoundVector &	par,
		const BoundSquareMatrix &	cov
	)		const

Getter method for the global coordinates of a SourceLink.

Parameters

gctx	The current geometry context object, e.g. alignment
slink	SourceLink that holds the necessary information
surfaceAccessor	function to extract surface from SourceLink
par	local position
cov	local covariance

Returns: vectors of the global coordinates and covariance of the SourceLink

Definition at line 51 of file SpacePointUtility.cpp.

View newest version in sPHENIX GitHub at line 51 of file SpacePointUtility.cpp

References Acts::eBoundLoc0, Acts::eBoundLoc1, Acts::ePos0, Acts::ePos1, Acts::ePos2, Acts::Surface::localToGlobal(), Acts::Surface::referenceFrame(), writeMapConfig::surface, ambiguity_solver_full_chain::x, and y.

Here is the call graph for this function:

Result< void > Acts::SpacePointUtility::recoverSpacePoint	(	SpacePointParameters &	spParams,
		double	stripLengthGapTolerance
	)		const

This function tests if a space point can be estimated by a more tolerant treatment of construction. In fact, this function indirectly allows shifts of the vertex.

Parameters

[in]	spParams	container that stores geometric parameters and rules of the space point formation
[in]	stripLengthGapTolerance	Tolerance scaling factor of the gap between strip detector elements

Returns: indicator if the test was successful

The following code considers an overshoot of m and n in the same direction of their SDE. The term "overshoot" represents the amount of m or n outside its regular interval (-1, 1). It calculates which overshoot is worse. In order to compare both, the overshoot in n is projected onto the first surface by considering the normalized projection of r onto q. This allows a rescaling of the overshoot. The worse overshoot will be set to +/-1, the parameter with less overshoot will be moved towards 0 by the worse overshoot. In order to treat both SDEs equally, the rescaling eventually needs to be performed several times. If these shifts allows m and n to be in the limits, the space point can be stored.

Note: This shift can be understood as a shift of the particle's trajectory. This is leads to a shift of the vertex. Since these two points are treated independently from other measurement, it is also possible to consider this as a change in the slope of the particle's trajectory. The would also move the vertex position.

Definition at line 198 of file SpacePointUtility.cpp.

View newest version in sPHENIX GitHub at line 198 of file SpacePointUtility.cpp

References Acts::SpacePointParameters::firstBtmToTop, Acts::SpacePointParameters::firstBtmToTopXvtxToFirstMid2, Acts::SpacePointParameters::limit, Acts::SpacePointParameters::limitExtended, Acts::SpacePointParameters::m, m_error, Acts::SpacePointParameters::mag_firstBtmToTop, Acts::SpacePointParameters::n, Acts::SpacePointParameters::secondBtmToTop, and Acts::SpacePointParameters::vtxToSecondMid2.

Vector2 Acts::SpacePointUtility::rhoZCovariance	(	const GeometryContext &	gctx,
		const Surface &	surface,
		const Vector3 &	globalPos,
		const SquareMatrix2 &	localCov
	)		const

Get rho and z covariance from the local position and covariance.

Parameters

gctx	The current geometry context object, e.g. alignment
surface	The surface associated
globalPos	The global position
localCov	The local covariance matrix

Returns: (rho, z) components of the global covariance

Definition at line 116 of file SpacePointUtility.cpp.

View newest version in sPHENIX GitHub at line 116 of file SpacePointUtility.cpp

References Acts::ePos0, Acts::ePos1, Acts::ePos2, Acts::Surface::referenceFrame(), ambiguity_solver_full_chain::x, and y.

Referenced by calcRhoZVars().

Here is the call graph for this function:

Here is the caller graph for this function:

Member Data Documentation

SpacePointBuilderConfig Acts::SpacePointUtility::m_config

private

Definition at line 169 of file SpacePointUtility.hpp.

View newest version in sPHENIX GitHub at line 169 of file SpacePointUtility.hpp

std::error_code Acts::SpacePointUtility::m_error

private

Definition at line 170 of file SpacePointUtility.hpp.

View newest version in sPHENIX GitHub at line 170 of file SpacePointUtility.hpp

Referenced by calcPerpendicularProjection(), calculateStripSPPosition(), differenceOfMeasurementsChecked(), and recoverSpacePoint().

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

acts/blob/sPHENIX/Core/include/Acts/Utilities/SpacePointUtility.hpp
acts/blob/sPHENIX/Core/src/Utilities/SpacePointUtility.cpp

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation