Detectors
Particle detectors are the tools used by physicists to explore the interior of matter.

Take a look at the DELPHI detectors

Introduction to detectors
When colliding high energy particles it is possible to create the conditions necessary to explore the interior of matter and to create new types of matter. To observe and identify the well known particles and also the possibly new states of matter, very sophisticated detectors are needed.

Modern detectors consist of many different components. The aim of the complex system of detectors surrounding the collision point is to:

• identify the particles
• determine their energy
• determine their direction

The type of produced particles, their energy and direction reveal the secrets of the collision mechanism and the interior of matter. The components of the detectors are stacked in such a way that the produced particles will go through the different layers.

An experiment consists of a large number of detectors, each of them having a well-defined task. Combining the information from all of them will produce a detailed picture of what happened in the particle collision. There are three main types of particle detectors:

• track detectors to determine the trajectory of charged particles
• calorimeters to determine the energy of both charged and neutral particles
• muon detectors to detect and identify muons

Below, a schematic picture of how various particles interact with the different components of a detector can be seen.


CPEP Illustration (http://www-pdg.lbl.gov/cpep/images/decay_chart.gif)

To visualize the path that particles take through a detector, below is a cross-section view of a detector (looking down the tube the colliding beams come from). Note the different places where the different particles will be detected.


CPEP Illustration (http://www-pdg.lbl.gov/cpep/images/end_view.gif)

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Schematic drawing of a typical modern detector

How such detectors look in reality is shown in the following pictures:

DELPHI tracking detector

DELPHI calorimeters and muon chambers

All information is registered electronically, and visualized by computers. The following pictures show examples of reconstructed reactions.

Z⁰ decays