LArSoft
v09_90_00
Liquid Argon Software toolkit - https://larsoft.org/
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Line surface perpendicular to x-axis. More...
#include "lardata/RecoObjects/SurfLine.h"
Go to the source code of this file.
Classes | |
class | trkf::SurfYZLine |
Namespaces | |
trkf | |
Line surface perpendicular to x-axis.
This class represents a line surface perpendicular to the global x-axis, or equivalently, parallel to the yz-plane.
The surface parameters and local coordinate system of this surface are the same as SurfYZPlane.
This surface is defined by four parameters, which are, (x0, y0, z0) - Local origin in global coordinates. phi - Rotation angle around x-axis.
The local uvw coordinate system is related to the global xyz coordinate system as follows.
u = x-x0 v = (y-y0)*cos(phi) + (z-z0)*sin(phi) w = -(y-y0)*sin(phi) + (z-z0)*cos(phi)
or inversely,
x = x0 + u y = y0 + v*cos(phi) - w*sin(phi) z = z0 + v*sin(phi) + w*cos(phi)
Track parameters on this type of surface are:
r = Signed impoact parameter. Absolute value of r is the perpendicular distance of the track to the v-axis at the point of closest approach to v-axis. Sign of r matches sign of L_v (v projection of angular momentum). v = V-coordinate of track at point of closest approach to v-axis. phi = Direction of track in u-w plane (phi = arctan(w/u)). eta = Pseudorapidity with respect to v-axis. q/p or 1/p = Inverse momentum.
In terms of these parameters, the point of closest approach to the v-axis is
u = -r sin(phi) v = v w = r cos(phi)
The unit direction vector is
du/ds = cos(phi) sech(eta) dv/ds = tanh(eta) dw/ds = sin(phi) sech(eta)
Inversely:
phi = atan(dw/du) = atan2(dw/ds, du/ds) eta = atanh(dv/ds) = asinh(dv/duw) r = w cos(phi) - u sin(phi)
Definition in file SurfYZLine.h.