hep.lcd.util.swim
Class Helix

java.lang.Object
  |
  +--hep.lcd.util.swim.Helix

public class Helix

extends Object

Given a particle of initial momentum, position and charge (p, r0, and iq), calculates its trajectory in a uniform magnetic field in the z-direction and determines its point of intersection (r_hit) with a cylinder centered at the origin with axis parallel to the z-axis and with ends. Trajectories are parameterized as fn of path length, s. There are no approximations made. Units are Tesla, cm, GeV/c

Author:

Ray Frey - Javaized by Tony Johnson

Source Code:

Helix.java

Field Summary

static int	PLANE_MINUSZ
static int	PLANE_PLUSZ
static int	PLANE_R
static int	PROBLEM

Constructor Summary

Helix(double B, double r_cyl, double z_pl)
Create a Helix swimmer

Method Summary

double[]	getCenter()
double[]	getIntersect()
int	getPlane()
double	getRadius()
boolean	isFlipped() Status of curvature flipping
void	setCurvatureFlip(boolean isFlipped) Flag for flipped curvature.
void	swim(double[] p, double[] r0_in, int iq)
void	swim(double[] p, double[] r0_in, int iq, boolean isFlipped)

Methods inherited from class java.lang.Object

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

Field Detail

PROBLEM

public static final int PROBLEM

PLANE_R

public static final int PLANE_R

PLANE_PLUSZ

public static final int PLANE_PLUSZ

PLANE_MINUSZ

public static final int PLANE_MINUSZ

Constructor Detail

Helix

public Helix(double B,
             double r_cyl,
             double z_pl)

Create a Helix swimmer

Parameters:

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

r_cyl - radius of cylinder

z_pl - z-coordinate of planes at end of cylinder (assumes symmetric placement at +/- z )

Method Detail

getIntersect

public double[] getIntersect()

Returns:

position at point of intersection (x,y,z)

getPlane

public int getPlane()

Returns:

cyl/plane which is first hit

getCenter

public double[] getCenter()

getRadius

public double getRadius()

swim

public void swim(double[] p,
                 double[] r0_in,
                 int iq,
                 boolean isFlipped)

Parameters:

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

r0 - initial position (x0,y0,z0)

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

isFlipped - curvature flipping option

See Also:

setCurvatureFlip(boolean)

swim

public void swim(double[] p,
                 double[] r0_in,
                 int iq)

Parameters:

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

r0 - initial position (x0,y0,z0)

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

setCurvatureFlip

public void setCurvatureFlip(boolean isFlipped)

Flag for flipped curvature.
This enables us to compare this Helix with GISMO hits for example.

Parameters:

isFlipped - true if curvatures should be flipped (default: with flipping)

See Also:

isFlipped()

isFlipped

public boolean isFlipped()

Status of curvature flipping

Returns:

true if curvature flipping option is on

See Also:

setCurvatureFlip(boolean)