Straw tracker
Encyclopedia
A straw tracker is a type of particle detector
which uses many straw chamber
s to track the path of a particle
. The path is determined by the best fit to all the straws with hits. Since the time for a particular straw to produce a signal is proportional to the distance of the particle's closest approach to that chamber's wire, if a particle on a predictable path (e.g. a helix
in a magnetic field
) passes through many straws, the path of the particle can be determined more precisely than the size of any particular straw.
Particle detector
In experimental and applied particle physics, nuclear physics, and nuclear engineering, a particle detector, also known as a radiation detector, is a device used to detect, track, and/or identify high-energy particles, such as those produced by nuclear decay, cosmic radiation, or reactions in a...
which uses many straw chamber
Straw chamber
A straw chamber is a type of Gaseous ionization detector. It is a long tube with a wire down the center and a gas which becomes ionized when a particle passes through. A potential difference is maintained between the wire and the walls of the tube, so that once the gas is ionized electrons move...
s to track the path of a particle
Elementary particle
In particle physics, an elementary particle or fundamental particle is a particle not known to have substructure; that is, it is not known to be made up of smaller particles. If an elementary particle truly has no substructure, then it is one of the basic building blocks of the universe from which...
. The path is determined by the best fit to all the straws with hits. Since the time for a particular straw to produce a signal is proportional to the distance of the particle's closest approach to that chamber's wire, if a particle on a predictable path (e.g. a helix
Helix
A helix is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helixes are coil springs and the handrails of spiral staircases. A "filled-in" helix – for...
in a magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
) passes through many straws, the path of the particle can be determined more precisely than the size of any particular straw.