Types of Detector "Tracks"

In a multi-layered detector such as SLD there are five distinguishable classes of tracks.

Electron (or positron)

Charged particle track in the vertex and drift chambers (tracking system) and point towards an electromagnetic shower shape in the calorimeter. The curvature of the track in the magnetic field tells us the charge of the particle.

Photon

Electromagnetic shower shape in the calorimeter with no associated track in tracking system.

Charged Hadron

Charged particle track in vertex and drift chambers (tracking system), pointing towards an hadronic shower shape in the calorimeter. Charged hadrons that show tracks are protons, charged pions, or charged kaons. All other charged hadrons are too short-lived to create tracks and their existence is reconstructed from the observation of their decay products with the correct total mass-energy. Particle identification systems are included to distinguish these three track types.

Neutral Hadron

Hadronic shower shape in the calorimeter with no associated track in tracking system. These could be a neutron, a neutral pion, or a neutral kaon. Other neutral hadrons are too short-lived to create showers and their existence is reconstructed from the observation of their decay products with the correct total mass-energy.

Muon

Track in tracking system that points into calorimeter with no associated shower. Matching track in outer tracker.