Helix parametrization that uses ROOT TVector3. More...

#include <StPicoHelix.h>

Inheritance diagram for StPicoHelix:

Public Member Functions
	StPicoHelix ()
	Default constructor.

	StPicoHelix (Double_t c, Double_t dip, Double_t phase, const TVector3 &o, Int_t h=-1)

	StPicoHelix (const StPicoHelix &)
	Copy constructor.

virtual	~StPicoHelix ()
	Destructor.

Double_t	dipAngle () const
	Return dip angle.

Double_t	curvature () const
	Return curvature: 1/R in xy-plane.

Double_t	phase () const
	Return phase: aziumth in xy-plane measured from ring center.

Double_t	xcenter () const
	Return x-center of circle in xy-plane.

Double_t	ycenter () const
	Return y-center of circle in xy-plane.

Int_t	h () const
	Return -sign(q*B);.

const TVector3 &	origin () const
	Return origin of the helix = starting point.

void	setParameters (Double_t c, Double_t dip, Double_t phase, const TVector3 &o, Int_t h)
	Set helix parameters.

Double_t	x (Double_t s) const
	coordinates of helix at point s

Double_t	y (Double_t s) const

Double_t	z (Double_t s) const

TVector3	at (Double_t s) const

Double_t	cx (Double_t s) const
	pointing vector of helix at point s

Double_t	cy (Double_t s) const

Double_t	cz (Double_t s=0) const

TVector3	cat (Double_t s) const

Double_t	period () const
	returns period length of helix

pair< Double_t, Double_t >	pathLength (Double_t r) const
	path length at given r (cylindrical r)

pair< Double_t, Double_t >	pathLength (Double_t r, Double_t x, Double_t y)
	path length at given r (cylindrical r, cylinder axis at x,y)

Double_t	pathLength (const TVector3 &p, Bool_t scanPeriods=true) const
	path length at distance of closest approach to a given point

Double_t	pathLength (const TVector3 &r, const TVector3 &n) const
	path length at intersection with plane

Double_t	pathLength (Double_t x, Double_t y) const
	path length at distance of closest approach in the xy-plane to a given point

pair< Double_t, Double_t >	pathLengths (const StPicoHelix &, Double_t minStepSize=10 micrometer, Double_t minRange=10 centimeter) const
	path lengths at dca between two helices

Double_t	distance (const TVector3 &p, Bool_t scanPeriods=true) const
	minimal distance between point and helix

Bool_t	valid (Double_t world=1.e+5) const
	checks for valid parametrization

Int_t	bad (Double_t world=1.e+5) const

virtual void	moveOrigin (Double_t s)
	Move the origin along the helix to s which becomes then s=0.

Static Public Attributes
static const Double_t	NoSolution = 3.e+33

Protected Member Functions
void	setCurvature (Double_t)
	Set curvature of the helix.

void	setPhase (Double_t)
	Set phase of the helix. More...

void	setDipAngle (Double_t)
	Set dip angle of the helix.

Double_t	fudgePathLength (const TVector3 &) const
	Value of S where distance in x-y plane is minimal.

Protected Attributes
Bool_t	mSingularity
	true for straight line case (B=0)

TVector3	mOrigin
	starting point of a helix

Double_t	mDipAngle
	Dip angle.

Double_t	mCurvature
	Curvature = 1/R.

Double_t	mPhase
	Phase.

Int_t	mH
	-sign(q*B);

Double_t	mCosDipAngle
	Cos of dip angle.

Double_t	mSinDipAngle
	Sin of dip angle.

Double_t	mCosPhase
	Cos of phase.

Double_t	mSinPhase

Detailed Description

Helix parametrization that uses ROOT TVector3.

Parametrization of a helix (modification of StHelix). Can also cope with straight tracks, i.e. with zero curvature. This represents only the mathematical model of a helix. See the SCL user guide for more.