marlintpc::localHelix Class Reference

Local Helix. More...

#include <SimpleHelixTrackModel.h>

Public Member Functions
	localHelix (const double *, const double *, const double)
	Constructor. More...
void	dump () const
	Dump helix.
TMatrixD	propagateTo (const double *, const double)
	Propagate stepwise (close) to point. More...
simpleHelix	getSimpleHelix () const
	Get simple helix. More...

Detailed Description

Local Helix.

Utilities for local helix track model build from perigee parameters and magnetic field at the PCA (point of closest approach) to the reference point, assuming constant magnetic field in arbitrary direction.

In a local system a simple helix is used. The offset of the local system is the PCA of the track (to the reference point) and the directions are (p,n,h), h is the direction of the magnetic field, n = h x t / |h x t| with track direction t and p = n x h. The bending plane is defined by p and n and p is the local track direction at the PCA in this plane.

Implemented is a stepwise propagation in a changing (only locally constant) magnetic field.

Propagation and transformation jacobians according to Strandlie & Wittek (NIM A 566(2006) 687-698)

Author

C. Kleinwort, DESY (131112)

Constructor & Destructor Documentation

marlintpc::localHelix::localHelix	(	const double *	parameters,
		const double *	refPoint,
		const double	bScale
	)

Constructor.

Parameters

[in]	parameters	(global) helix parameters (at)
[in]	refPoint	reference point
[in]	bScale	scale factor for magnetic field (0/1)

Member Function Documentation

simpleHelix marlintpc::localHelix::getSimpleHelix

(

)

const

Get simple helix.

Get simple helix in global system at current reference point.

Returns

simple helix

TMatrixD marlintpc::localHelix::propagateTo	(	const double *	point,
		const double	mstep
	)

Propagate stepwise (close) to point.

Stepwise propagation in a changing (only locally constant) magnetic field. Reference point is changed to (PCA of) target.

Parameters

[in]	point	target (propagate to PCA)
[in]	mstep	maximal step size with constant magnetic field

Returns

analytical propagation jacobian

References marlintpc::localHelixAnalyticalJacobian().

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

• SimpleHelixTrackModel.h
• SimpleHelixTrackModel.cc