Algorithm for hit finding in the sensors of the CBM-STS. More...

#include <CbmStsAlgoFindHits.h>

Public Member Functions
	CbmStsAlgoFindHits ()
	Constructor.

	CbmStsAlgoFindHits (const CbmStsAlgoFindHits &)=delete
	Copy constructor (disabled)

CbmStsAlgoFindHits &	operator= (const CbmStsAlgoFindHits &)=delete
	Assignment operator (disabled)

virtual	~CbmStsAlgoFindHits ()
	Destructor

Long64_t	Exec (const std::vector< CbmStsCluster > &clustersF, const std::vector< CbmStsCluster > &clustersB, std::vector< CbmStsHit > &hits, UInt_t address, Double_t timeCutSig, Double_t timeCutAbs, Double_t dY, UInt_t nStrips, Double_t pitch, Double_t stereoF, Double_t stereoB, Double_t lorentzF, Double_t lorentzB, TGeoHMatrix *matrix)
	Execute algorithm.

Private Member Functions
void	CreateHit (Double_t xLocal, Double_t yLocal, Double_t varX, Double_t varY, Double_t varXY, const CbmStsCluster &clusterF, const CbmStsCluster &clusterB, UInt_t indexF, UInt_t indexB, Double_t du=0., Double_t dv=0.)
	Create a new hit in the output array.

void	GetClusterPosition (Double_t ClusterCentre, Double_t &xCluster, Int_t &side)

Int_t	GetSide (Double_t channel) const

std::pair< Int_t, Int_t >	GetStrip (UInt_t channel) const
	Get strip and side from module channel.

Bool_t	Intersect (Double_t xF, Double_t exF, Double_t xB, Double_t exB, Double_t &x, Double_t &y, Double_t &varX, Double_t &varY, Double_t &varXY)
	Intersection point of two strips / cluster centres.

Int_t	IntersectClusters (const CbmStsCluster &clusterF, const CbmStsCluster &clusterB, UInt_t indexF, UInt_t indexB)
	Find the intersection points of two clusters.

Bool_t	IsInside (Double_t x, Double_t y)
	Check whether a point (x,y) is inside the active area.

	ClassDef (CbmStsAlgoFindHits, 1)

Private Attributes
UInt_t	fAddress = 0
	Unique address for hits (sensor)

Double_t	fTimeCutSig = 0.
	Time cut on clusters in error units.

Double_t	fTimeCutAbs = 0.
	Time cut on clusters in ns.

UInt_t	fNofStrips = 0
	Number of strips.

Double_t	fDx = 0.
	Active size in x [cm].

Double_t	fDy = 0.
	Active size in y [cm].

Double_t	fPitch = 0.
	Strip pitch [cm].

Double_t	fStereoF = 0.
	Stereo angle front side [deg].

Double_t	fStereoB = 0.
	Stereo angle back side [deg].

Double_t	fLorentzF = 0.
	Lorentz shift correction front side [cm].

Double_t	fLorentzB = 0.
	Lorentz shift correction back side [cm].

TGeoHMatrix *	fMatrix = nullptr

Double_t	fTanStereoF = 0.
	///< Transformation matrix to global C.S.

Double_t	fTanStereoB = 0.
	Tangent of stereo angle back side.

Double_t	fErrorFac = 0.
	For calculation of the hit error.

std::vector< CbmStsHit > *	fHits = nullptr
	Output vector of hits.

Detailed Description

Algorithm for hit finding in the sensors of the CBM-STS.

Author: V.Friese v.fri.nosp@m.ese@.nosp@m.gsi.d.nosp@m.e; F. Boeck (FIAS)

Since: 23.03.2020

A hit is constructed from two clusters, one from the front side, the other one from the back side of the sensor, if they two clusters have a geometrical intersection in the active sensor area, and if they are compatible in time. The algorithm combines front-side with back-side clusters and checks for these conditions. The hit coordinates are transformed into the global coordinate system.

The loop over the clusters was optimised by F. Boeck for application to free-streaming data (not sorted into events).

Definition at line 38 of file CbmStsAlgoFindHits.h.

Constructor & Destructor Documentation

◆ CbmStsAlgoFindHits() [1/2]

CbmStsAlgoFindHits::CbmStsAlgoFindHits ( )

Constructor.

Definition at line 28 of file CbmStsAlgoFindHits.cxx.

◆ CbmStsAlgoFindHits() [2/2]

CbmStsAlgoFindHits::CbmStsAlgoFindHits ( const CbmStsAlgoFindHits & )

delete

Copy constructor (disabled)

◆ ~CbmStsAlgoFindHits()

virtual CbmStsAlgoFindHits::~CbmStsAlgoFindHits ( )

inlinevirtual

Destructor

Definition at line 54 of file CbmStsAlgoFindHits.h.

Member Function Documentation

◆ ClassDef()

CbmStsAlgoFindHits::ClassDef	(	CbmStsAlgoFindHits	,
		1	)

private

◆ CreateHit()

void CbmStsAlgoFindHits::CreateHit	(	Double_t	xLocal,
		Double_t	yLocal,
		Double_t	varX,
		Double_t	varY,
		Double_t	varXY,
		const CbmStsCluster &	clusterF,
		const CbmStsCluster &	clusterB,
		UInt_t	indexF,
		UInt_t	indexB,
		Double_t	du = 0.,
		Double_t	dv = 0. )

private

Create a new hit in the output array.

Parameters

xLocal	hit x coordinate in sensor system [cm]
yLocal	hit y coordinate in sensor system [cm]
varX	Variance in x [cm^2]
varY	Variance in y [cm^2]
varXY	Covariance of x and y [cm^2]
clusterF	Front-side cluster
clusterB	Back-side cluster
indexF	Index of front-side cluster
indexB	Index of back-side cluster
du	Error in u coordinate (across strips front side) [cm]
dv	Error in v coordinate (across strips back side) [cm]

Definition at line 33 of file CbmStsAlgoFindHits.cxx.

References fAddress, fHits, fMatrix, CbmStsCluster::GetTime(), CbmStsCluster::GetTimeError(), and Cbm::GeometryUtils::LocalToMasterCovarianceMatrix().

Referenced by IntersectClusters().

◆ Exec()

Long64_t CbmStsAlgoFindHits::Exec	(	const std::vector< CbmStsCluster > &	clustersF,
		const std::vector< CbmStsCluster > &	clustersB,
		std::vector< CbmStsHit > &	hits,
		UInt_t	address,
		Double_t	timeCutSig,
		Double_t	timeCutAbs,
		Double_t	dY,
		UInt_t	nStrips,
		Double_t	pitch,
		Double_t	stereoF,
		Double_t	stereoB,
		Double_t	lorentzF,
		Double_t	lorentzB,
		TGeoHMatrix *	matrix )

Execute algorithm.

Parameters

clustersF	Input clusters front side
clusterB	Input clusters back side
hits	Output hits
Hit	address ( = module address)
timeCutSig	Time cut in units of cluster time error
timeCutAbs	Time cut in ns
dY	Vertical size of the active sensor area [cm]
nStrips	Number of strips (same for both sensor sides)
pitch	Strip ptch [cm] (same for both sensor sides)
stereoF	Strip stereo angle sensor front side [deg]
stereoB	Strip stereo angle sensor back side [deg]
lorentzF	Mean Lorentz shift front side (electrons) [cm]
lorentzB	Mean Lorentz shift back side (holes) [cm]
matrix	Transformation matrix from local to global C.S.

Returns: Number of created hits

Definition at line 72 of file CbmStsAlgoFindHits.cxx.

References fAddress, fDx, fDy, fErrorFac, fHits, fLorentzB, fLorentzF, fMatrix, fNofStrips, fPitch, fStereoB, fStereoF, fTanStereoB, fTanStereoF, CbmStsCluster::GetTime(), CbmStsCluster::GetTimeError(), hits, and IntersectClusters().

Referenced by CbmStsRecoModule::FindHits().

◆ GetClusterPosition()

void CbmStsAlgoFindHits::GetClusterPosition	(	Double_t	ClusterCentre,
		Double_t &	xCluster,
		Int_t &	side )

private

Get the cluster position at the top edge of the sensor.

Parameters

[in]	centre	Cluster centre in (module) channel units
[out]	xCluster	Cluster position at readout edge
[out]	side	Sensor side [0 = front, 1 = back]

A correction for the Lorentz shift is applied.

Definition at line 165 of file CbmStsAlgoFindHits.cxx.

References fLorentzB, fLorentzF, fPitch, and GetStrip().

Referenced by IntersectClusters().

◆ GetSide()

Int_t CbmStsAlgoFindHits::GetSide ( Double_t channel ) const

inlineprivate

Get the side of the sensor from the module channel number The channel number can also be the cluster position, so it needs not be integer.

Parameters

channel Channel number

Returns: Sensor side ( 0 = front, 1 = back)

Definition at line 115 of file CbmStsAlgoFindHits.h.

References fNofStrips.

◆ GetStrip()

pair< Int_t, Int_t > CbmStsAlgoFindHits::GetStrip ( UInt_t channel ) const

private

Get strip and side from module channel.

Parameters

[in]	channel	Channel number in module
[in]	sensorId	Sensor index in module @value Pair of strip number and side

Note: This must be the inverse of GetModuleChannel.

Definition at line 199 of file CbmStsAlgoFindHits.cxx.

References fNofStrips.

Referenced by GetClusterPosition().

◆ Intersect()

Bool_t CbmStsAlgoFindHits::Intersect	(	Double_t	xF,
		Double_t	exF,
		Double_t	xB,
		Double_t	exB,
		Double_t &	x,
		Double_t &	y,
		Double_t &	varX,
		Double_t &	varY,
		Double_t &	varXY )

private

Intersection point of two strips / cluster centres.

Parameters

[in]	xF	x coordinate on read-out edge, front side [cm]
[in]	exF	uncertainty on xF [cm]
[in]	xB	x coordinate on read-out edge, back side [cm]
[in]	eBF	uncertainty on xB [cm]
[out]	x	x coordinate of crossing [cm]
[out]	y	y coordinate of crossing [cm]
[out]	varX	Variance in x [cm^2]
[out]	varY	Variance in y [cm^2]
[out]	varXY	Covariance of x and y [cm^2]

Returns: kTRUE if intersection is inside active area.

This function calculates the intersection point of two lines starting at xF and xB at the top edge with slopes corresponding to the respective stereo angle.

All coordinates are in the sensor frame with the origin in the bottom left corner of the active area.

Definition at line 227 of file CbmStsAlgoFindHits.cxx.

References fDx, fDy, fErrorFac, fStereoB, fStereoF, fTanStereoB, fTanStereoF, IsInside(), x, and y.

Referenced by IntersectClusters().

◆ IntersectClusters()

Int_t CbmStsAlgoFindHits::IntersectClusters	(	const CbmStsCluster &	clusterF,
		const CbmStsCluster &	clusterB,
		UInt_t	indexF,
		UInt_t	indexB )

private

Find the intersection points of two clusters.

Parameters

clusterF	Cluster on front side
clusterB	Cluster on back side
indexF	Index of cluster on front side
indexB	Index of cluster on back side

Returns: Number of intersection points inside active area

For each intersection point, a hit is created.

Definition at line 283 of file CbmStsAlgoFindHits.cxx.

References CreateHit(), fDx, fDy, fPitch, fStereoB, fStereoF, fTanStereoB, fTanStereoF, GetClusterPosition(), CbmStsCluster::GetPosition(), CbmStsCluster::GetPositionError(), and Intersect().

Referenced by Exec().

◆ IsInside()

Bool_t CbmStsAlgoFindHits::IsInside	(	Double_t	x,
		Double_t	y )

private

Check whether a point (x,y) is inside the active area.

Parameters

x	x coordinate in the local c.s. [cm]
y	y coordinate in the local c.s. [cm]

Returns: kTRUE if inside active area.

The coordinates have to be given in the local coordinate system (origin in the sensor centre).

Definition at line 364 of file CbmStsAlgoFindHits.cxx.

References fDx, fDy, x, and y.

Referenced by Intersect().

◆ operator=()

CbmStsAlgoFindHits & CbmStsAlgoFindHits::operator= ( const CbmStsAlgoFindHits & )

delete

Assignment operator (disabled)

Member Data Documentation

◆ fAddress

UInt_t CbmStsAlgoFindHits::fAddress = 0

private

Unique address for hits (sensor)

Definition at line 176 of file CbmStsAlgoFindHits.h.

Referenced by CreateHit(), and Exec().

◆ fDx

Double_t CbmStsAlgoFindHits::fDx = 0.

private

Active size in x [cm].

Definition at line 180 of file CbmStsAlgoFindHits.h.

Referenced by Exec(), Intersect(), IntersectClusters(), and IsInside().

◆ fDy

Double_t CbmStsAlgoFindHits::fDy = 0.

private

Active size in y [cm].

Definition at line 181 of file CbmStsAlgoFindHits.h.

Referenced by Exec(), Intersect(), IntersectClusters(), and IsInside().

◆ fErrorFac

Double_t CbmStsAlgoFindHits::fErrorFac = 0.

private

For calculation of the hit error.

Definition at line 190 of file CbmStsAlgoFindHits.h.

Referenced by Exec(), and Intersect().

◆ fHits

std::vector<CbmStsHit>* CbmStsAlgoFindHits::fHits = nullptr

private

Output vector of hits.

Definition at line 193 of file CbmStsAlgoFindHits.h.

Referenced by CreateHit(), and Exec().

◆ fLorentzB

Double_t CbmStsAlgoFindHits::fLorentzB = 0.

private

Lorentz shift correction back side [cm].

Definition at line 186 of file CbmStsAlgoFindHits.h.

Referenced by Exec(), and GetClusterPosition().

◆ fLorentzF

Double_t CbmStsAlgoFindHits::fLorentzF = 0.

private

Lorentz shift correction front side [cm].

Definition at line 185 of file CbmStsAlgoFindHits.h.

Referenced by Exec(), and GetClusterPosition().

◆ fMatrix

TGeoHMatrix* CbmStsAlgoFindHits::fMatrix = nullptr

private

Definition at line 187 of file CbmStsAlgoFindHits.h.

Referenced by CreateHit(), and Exec().

◆ fNofStrips

UInt_t CbmStsAlgoFindHits::fNofStrips = 0

private

Number of strips.

Definition at line 179 of file CbmStsAlgoFindHits.h.

Referenced by Exec(), GetSide(), and GetStrip().

◆ fPitch

Double_t CbmStsAlgoFindHits::fPitch = 0.

private

Strip pitch [cm].

Definition at line 182 of file CbmStsAlgoFindHits.h.

Referenced by Exec(), GetClusterPosition(), and IntersectClusters().

◆ fStereoB

Double_t CbmStsAlgoFindHits::fStereoB = 0.

private

Stereo angle back side [deg].

Definition at line 184 of file CbmStsAlgoFindHits.h.

Referenced by Exec(), Intersect(), and IntersectClusters().

◆ fStereoF

Double_t CbmStsAlgoFindHits::fStereoF = 0.

private

Stereo angle front side [deg].

Definition at line 183 of file CbmStsAlgoFindHits.h.

Referenced by Exec(), Intersect(), and IntersectClusters().

◆ fTanStereoB

Double_t CbmStsAlgoFindHits::fTanStereoB = 0.

private

Tangent of stereo angle back side.

Definition at line 189 of file CbmStsAlgoFindHits.h.

Referenced by Exec(), Intersect(), and IntersectClusters().

◆ fTanStereoF

Double_t CbmStsAlgoFindHits::fTanStereoF = 0.

private

///< Transformation matrix to global C.S.

Tangent of stereo angle front side

Definition at line 188 of file CbmStsAlgoFindHits.h.

Referenced by Exec(), Intersect(), and IntersectClusters().

◆ fTimeCutAbs

Double_t CbmStsAlgoFindHits::fTimeCutAbs = 0.

private

Time cut on clusters in ns.

Definition at line 178 of file CbmStsAlgoFindHits.h.

◆ fTimeCutSig

Double_t CbmStsAlgoFindHits::fTimeCutSig = 0.

private

Time cut on clusters in error units.

Definition at line 177 of file CbmStsAlgoFindHits.h.

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

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ CbmStsAlgoFindHits() [1/2]

◆ CbmStsAlgoFindHits() [2/2]

◆ ~CbmStsAlgoFindHits()

Member Function Documentation

◆ ClassDef()

◆ CreateHit()

◆ Exec()

◆ GetClusterPosition()

◆ GetSide()

◆ GetStrip()

◆ Intersect()

◆ IntersectClusters()

◆ IsInside()

◆ operator=()

Member Data Documentation

◆ fAddress

◆ fDx

◆ fDy

◆ fErrorFac

◆ fHits

◆ fLorentzB

◆ fLorentzF

◆ fMatrix

◆ fNofStrips

◆ fPitch

◆ fStereoB

◆ fStereoF

◆ fTanStereoB

◆ fTanStereoF

◆ fTimeCutAbs

◆ fTimeCutSig