PANDA::CircleTools Namespace Reference

Functions
double	PtFromCircle (double B, double r)
	Calculates the transverse momentum from a given radius. More...
double	PhiForHit (FairHit *hit, TVector3 &circle)
	Calculates the angle phi for a hit depending on the circle center. More...
int	RotationDirection (FairHit *firstHit, FairHit *nextHit, TVector3 &circle)
	Determines the rotation direction of the particle If the particle rotates anticlockwise it returns -1, alse it returns +1. More...
TVector2	PositionOnCircle (FairHit *hit, TVector3 &circle)
	Determins the position on the circle for a given hit. More...
TVector2	PtOnCircle (FairHit *hit, TVector3 &circle, int direction, double B)
	Rotates the transverse momentum by phi to determine the track's momentum direction at a hit point. More...

Function Documentation

PhiForHit()

double PANDA::CircleTools::PhiForHit	(	FairHit *	hit,
		TVector3 &	circle
	)

Calculates the angle phi for a hit depending on the circle center.

Parameters

[in]	hit	A hit
[in]	circle	The parameters of the circle given in a TVector3 as circle Center and radius (X, Y, R)
[out]	Phi	in [rad]

Definition at line 43 of file PndCircleTools.h.

Referenced by PositionOnCircle(), PtOnCircle(), and RotationDirection().

{
  TVector2 hitV(hit->GetX(), hit->GetY());
  TVector2 circleCenter(circle.X(), circle.Y());
  return (hitV - circleCenter).Phi();
}

PositionOnCircle()

TVector2 PANDA::CircleTools::PositionOnCircle	(	FairHit *	hit,
		TVector3 &	circle
	)

Determins the position on the circle for a given hit.

Parameters

[in]	hit	A hit of the track
[in]	circle	The circle parameters that describe the track
[out]	result	The position on the circle for a given hit

Definition at line 78 of file PndCircleTools.h.

References PhiForHit().

{

  double phiHit = PhiForHit(hit, circle);

  TVector2 circleCenter(circle.X(), circle.Y());
  TVector2 result(circle.Z(), 0);
  result = result.Rotate(phiHit);
  result += circleCenter;
  return result;
}

PtFromCircle()

double PANDA::CircleTools::PtFromCircle	(	double	B,
		double	r
	)

Calculates the transverse momentum from a given radius.

Parameters

[in]	B	The magnetic field in [T]
[in]	r	The radius of the circle in [cm]
[out]	The	transverse momentum in [GeV/c]

Definition at line 28 of file PndCircleTools.h.

Referenced by PtOnCircle().

{
  // 0.01 to recalculate [cm] in [m]
  // 0.3 from constants when setting Lorentz force equal to centrifugal force
  // pT [GeV/c] = 0.3 * B [T] * abs(r [cm]) * 0.01;
  return 0.003 * B * abs(r);
}

PtOnCircle()

TVector2 PANDA::CircleTools::PtOnCircle	(	FairHit *	hit,
		TVector3 &	circle,
		int	direction,
		double	B
	)

Rotates the transverse momentum by phi to determine the track's momentum direction at a hit point.

Parameters

[in]	hit	A hit of the track
[in]	circle	The circle parameters that describe the track
[in]	direction	The moving direction of the particle (similar to charge)
[in]	B	The magnetic field
[out]	result	Momentum direction at the given hit point

Definition at line 99 of file PndCircleTools.h.

References PhiForHit(), CAMath::Pi(), and PtFromCircle().

{
  TVector2 result(0, PtFromCircle(B, circle.Z()));
  double phiOnCircle = PhiForHit(hit, circle);
  if (direction > 0) {
    phiOnCircle += TMath::Pi();
  }
  return result.Rotate(phiOnCircle);
}

RotationDirection()

int PANDA::CircleTools::RotationDirection	(	FairHit *	firstHit,
		FairHit *	nextHit,
		TVector3 &	circle
	)

Determines the rotation direction of the particle If the particle rotates anticlockwise it returns -1, alse it returns +1.

Parameters

[in]	firstHit	A first hit of the track
[in]	nextHit	A hit of the track occuring after the first hit
[in]	circle	The track parameters as circle approximation (X, Y, R)
[out]	If	the particle rotates anticlockwise it returns -1, alse it returns +1

Definition at line 60 of file PndCircleTools.h.

References PhiForHit().

{
  double phiFirst = PhiForHit(firstHit, circle);
  double phiNext = PhiForHit(nextHit, circle);

  if (phiNext - phiFirst > 0)
    return -1;
  else
    return 1;
}