Particle Detectors

Turning back to the hardware of high energy physics (), I should point out that it is not enough to build accelerators capable of delivering enough energy to a collision to create more massive and more exotic particles - one must also have some way to ``see'' those particles once they are created. This is in principle rather challenging, since they are all apt to be moving at near light speed and are certainly too small to detect with visible light; moreover, usually they don't last very long - the heavier the particle, the larger the variety of lighter particles into which it might decay! This rule-of-thumb works quite well in general, so that exceptions (long-lived heavy particles) stand out rather dramatically; more on this later.

In practice it is surprisingly easy to ``see'' elementary particles, once you get used to a new way of ``seeing.'' The basis of all particle detectors is that charged particles cause ionization where they pass through matter. The ions they leave behind form a ``track'' that can be detected in several ways.

• Scintillating!
• Clouds, Bubbles and Wires