Public Member Functions
	HelixClass_double ()
	Constructor. More...

	~HelixClass_double ()
	Destructor.

void	Initialize_VP (double pos, double mom, double q, double B)
	Initialization of helix using More...

void	Initialize_BZ (double xCentre, double yCentre, double radius, double bZ, double phi0, double B, double signPz, double zBegin)
	Initialization of helix according to the following parameterization x = xCentre + radiuscos(bZz + phi0) y = yCentre + radiussin(bZz + phi0) where (x,y,z) - position of point on the helix More...

void	Initialize_Canonical (double phi0, double d0, double z0, double omega, double tanlambda, double B)
	Canonical (LEP-wise) parameterisation with the following parameters More...

const double *	getMomentum ()
	Returns momentum of particle at the point of closest approach to IP

const double *	getReferencePoint ()
	Returns reference point of track

double	getPhi0 ()
	Returns Phi angle of the momentum vector at the point of closest approach to IP

double	getD0 ()
	Returns signed distance of closest approach to IP in the R-Phi plane

double	getZ0 ()
	Returns z coordinate of the point of closest approach to IP in the R-Phi plane

double	getOmega ()
	Returns signed curvature of the track

double	getTanLambda ()
	Returns tangent of dip angle of the track

double	getPXY ()
	Returns transverse momentum of the track

double	getXC ()
	Returns x coordinate of circumference.

double	getYC ()
	Returns y coordinate of circumference.

double	getRadius ()
	Returns radius of circumference.

double	getPointInXY (double x0, double y0, double ax, double ay, double ref, double point)
	Returns helix intersection point with the plane parallel to z axis. More...

double	getPointInZ (double zLine, double ref, double point)
	Returns helix intersection point with the plane perpendicular to z axis. More...

double	getDistanceToPoint (double xPoint, double Distance)
	Return distance of the closest approach of the helix to arbitrary 3D point in space. More...

double	getDistanceToPoint (const double *xPoint, double distCut)
	Return distance of the closest approach of the helix to arbitrary 3D point in space. More...

double	getDistanceToPoint (const std::vector< double > &xPoint, double distCut)

double	getPointOnCircle (double Radius, double ref, double point)
	This method calculates coordinates of both intersection of the helix with a cylinder. More...

double	getDistanceToHelix (HelixClass_double helix, double pos, double *mom)
	Returns distance between two helixes Output : pos[3] - position of the point of closest approach mom[3] - momentum of V0

void	setHelixEdges (double xStart, double xEnd)
	Set Edges of helix.

double *	getStartingPoint ()
	Returns starting point of helix.

double *	getEndPoint ()
	Returns endpoint of helix.

double	getBz ()
	Returns BZ for the second parameterization.

double	getPhiZ ()
	Returns Phi for the second parameterization.

void	getExtrapolatedMomentum (double pos, double momentum)
	Returns extrapolated momentum.

double	getCharge ()
	Returns charge.

Constructor & Destructor Documentation

HelixClass_double::HelixClass_double ( )

Constructor.

Initializations of constants which are used to calculate various parameters associated with helix.

Member Function Documentation

double HelixClass_double::getDistanceToPoint	(	double *	xPoint,
		double *	Distance
	)

Return distance of the closest approach of the helix to
arbitrary 3D point in space.

xPoint[3] - coordinates of
space point. Distance[3] - vector of distances of helix to
a given point in various projections :
Distance[0] - distance in R-Phi plane
Distance[1] - distance along Z axis
Distance[2] - 3D distance

Referenced by getDistanceToPoint().

double HelixClass_double::getDistanceToPoint	(	const double *	xPoint,
		double	distCut
	)

Return distance of the closest approach of the helix to
arbitrary 3D point in space.

xPoint[3] - coordinates of
space point. distCut - limit on the distance between helix
and the point to reduce calculation time
If R-Phi is found to be greater than distCut, rPhi distance is returned
If the R-Phi distance is not too big, than the exact 3D distance is returned
This function can be used, if the exact distance is not always needed

References getDistanceToPoint().

double HelixClass_double::getPointInXY	(	double	x0,
		double	y0,
		double	ax,
		double	ay,
		double *	ref,
		double *	point
	)

Returns helix intersection point with the plane
parallel to z axis.

Plane is defined by two coordinates
of the point belonging to the plane (x0,y0) and normal
vector (ax,ay). ref[3] is the reference point of the helix.
point[3] - returned vector holding the coordinates of
intersection point

double HelixClass_double::getPointInZ	(	double	zLine,
		double *	ref,
		double *	point
	)

Returns helix intersection point with the plane
perpendicular to z axis.

Plane is defined by z coordinate
of the plane. ref[3] is the reference point of the helix.
point[3] - returned vector holding the coordinates of
intersection point

double HelixClass_double::getPointOnCircle	(	double	Radius,
		double *	ref,
		double *	point
	)

This method calculates coordinates of both intersection
of the helix with a cylinder.

Rotational symmetry with respect to z axis is assumed,
meaning that cylinder axis corresponds to the z axis
of reference frame.
Inputs :
Radius - radius of cylinder.
ref[3] - point of closest approach to the origin of the helix.
Output :
point[6] - coordinates of intersection point.
Method returns also generic time, defined as the
ratio of helix length from reference point to the intersection
point to the particle momentum

Referenced by getDistanceToHelix().

void HelixClass_double::Initialize_BZ	(	double	xCentre,
		double	yCentre,
		double	radius,
		double	bZ,
		double	phi0,
		double	B,
		double	signPz,
		double	zBegin
	)

Initialization of helix according to the following
parameterization
x = xCentre + radius*cos(bZ*z + phi0)
y = yCentre + radius*sin(bZ*z + phi0)
where (x,y,z) - position of point on the helix

(xCentre,yCentre) is the centre of circumference in R-Phi plane
radius is the radius of circumference
bZ is the helix slope parameter
phi0 is the initial phase of circumference
B is the magnetic field (in Tesla)
signPz is the sign of the z component of momentum vector
zBegin is the z coordinate of the reference point

void HelixClass_double::Initialize_Canonical	(	double	phi0,
		double	d0,
		double	z0,
		double	omega,
		double	tanlambda,
		double	B
	)

Canonical (LEP-wise) parameterisation with the following parameters

phi0 - Phi angle of momentum vector at the point of
closest approach to IP in R-Phi plane;
d0 - signed distance of closest approach in R-Phi plane;
z0 - z coordinate of the point of closest approach to IP in R-Phi plane;
omega - signed curvature;
tanlambda - tangent of dip angle;
B - magnetic field (in Tesla)

void HelixClass_double::Initialize_VP	(	double *	pos,
		double *	mom,
		double	q,
		double	B
	)

Initialization of helix using

position of the reference point : pos[3];
momentum vector at the reference point : mom[3];
particle charge : q;
magnetic field (in Tesla) : B

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

HelixClass_double.h
HelixClass_double.cc

Public Member Functions

Constructor & Destructor Documentation

Member Function Documentation