org.lcsim.util.swim

Class HelixSwimmer

java.lang.Object

org.lcsim.util.swim.HelixSwimmer

Direct Known Subclasses:

HelixSwimmerYField

public class HelixSwimmer
extends Object

A simple helix swimmer for use in org.lcsim. Uses standard lcsim units Tesla, mm, GeV. This swimmer works for charged and neutral tracks.

For more info on swimming see this paper by Paul Avery.

Version:

$Id: HelixSwimmer.java,v 1.22 2011/04/17 14:22:13 grefe Exp $

Author:

jstrube

Field Summary

Fields

Modifier and Type	Field and Description
protected double	_charge
protected SpaceVector	_momentum
protected Trajectory	_trajectory
protected double	field

Constructor Summary

Constructors

Constructor and Description
HelixSwimmer(double B) Creates a new instance of HelixSwimmer

Method Summary

Methods

Modifier and Type	Method and Description
double	getDistanceToCylinder(double r, double z)
double	getDistanceToPoint(Hep3Vector point)
double	getDistanceToPolyhedra(double r, int nsides)
double	getDistanceToRadius(double r)
double	getDistanceToZ(double z)
SpaceVector	getMomentumAtLength(double alpha) Returns the momentum on a point on the track at a distance from the origin
SpacePoint	getPointAtDistance(double alpha) Deprecated. in favor of getPointAtLength
SpacePoint	getPointAtLength(double alpha) Returns a SpacePoint at the length alpha from the origin along the track
double	getTrackLengthToPoint(Hep3Vector point) Returns the distance along the trajectory to get to the point of closest approach
Trajectory	getTrajectory()
void	setTrack(Hep3Vector p, Hep3Vector r0, int iq) Deprecated. in favor of setTrack(SpaceVector p, SpacePoint r0, int iq) because this method has an ambiguous signature
void	setTrack(Hep3Vector p0, SpacePoint r0, double q) Sets parameters for helix swimmmer.
void	setTrack(Hep3Vector p0, SpacePoint r0, int iq) Sets parameters for helix swimmmer.
void	setTrack(Track t) Sets the parameters for the helix swimmer.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

field

protected double field

_trajectory

protected Trajectory _trajectory

_momentum

protected SpaceVector _momentum

_charge

protected double _charge

Constructor Detail

HelixSwimmer

public HelixSwimmer(double B)

Creates a new instance of HelixSwimmer

Parameters:

B - field strength in Tesla; uniform, solenoidal, directed along z-axis

Method Detail

setTrack

public void setTrack(Hep3Vector p0,
            SpacePoint r0,
            int iq)

Sets parameters for helix swimmmer.

Parameters:

p - 3-momentum (px,py,pz)

r0 - initial position(x0,y0,z0)

iq - charge iq = q/|e| = +1/0/-1

setTrack

public void setTrack(Hep3Vector p0,
            SpacePoint r0,
            double q)

Sets parameters for helix swimmmer.

Parameters:

p - 3-momentum (px,py,pz)

r0 - initial position(x0,y0,z0)

q - charge q = q/|e| = +1/0/-1

setTrack

@Deprecated
public void setTrack(Hep3Vector p,
                       Hep3Vector r0,
                       int iq)

Deprecated. in favor of setTrack(SpaceVector p, SpacePoint r0, int iq) because this method has an ambiguous signature

Sets parameters for helix swimmmer.

Parameters:

p - 3-momentum (px,py,pz)

r0 - initial position(x0,y0,z0)

iq - charge iq = q/|e| = +1/0/-1

setTrack

public void setTrack(Track t)

Sets the parameters for the helix swimmer. Uses the LCIOParameters class for conversion between track parameters and space and momentum representation

Parameters:

t - The track to approximate with a helix

getPointAtDistance

@Deprecated
public SpacePoint getPointAtDistance(double alpha)

Deprecated. in favor of getPointAtLength

Parameters:

alpha -

Returns:

a SpacePoint at the length alpha from the origin along the track

getPointAtLength

public SpacePoint getPointAtLength(double alpha)

Returns a SpacePoint at the length alpha from the origin along the track

Parameters:

alpha -

Returns:

a SpacePoint at the length alpha from the origin along the track

getDistanceToRadius

public double getDistanceToRadius(double r)

getDistanceToPolyhedra

public double getDistanceToPolyhedra(double r,
                            int nsides)

getDistanceToZ

public double getDistanceToZ(double z)

getDistanceToCylinder

public double getDistanceToCylinder(double r,
                           double z)

getTrackLengthToPoint

public double getTrackLengthToPoint(Hep3Vector point)

Returns the distance along the trajectory to get to the point of closest approach

Parameters:

point - The point to swim as close as possible to

Returns:

the length parameter by how much the trajectory has to be swum

getDistanceToPoint

public double getDistanceToPoint(Hep3Vector point)

getMomentumAtLength

public SpaceVector getMomentumAtLength(double alpha)

Returns the momentum on a point on the track at a distance from the origin

Parameters:

alpha - The 2D distance from the origin along the track

Returns:

The components of the momentum in a SpacePoint

getTrajectory

public Trajectory getTrajectory()