The detectors discussed to this point, scintillation counters, Cerenkov counters, proportional chambers, and drift chambers, can be found in some combination in most particle physics experiments. There are in addition other types of detectors that are used for specialized applications. These include such old standards as emulsions and bubble chambers, as well as the more recently developed transition radiation detectors and semiconductor detectors. This chapter contains a short discussion on some of the more common types of specialized detectors.

Bubble chambers

The bubble chamber was one of the most important detectors for particle physics experiments during the 1960s and early 1970s. Much of our knowledge of particle spectroscopy, strong interactions, and neutrino physics was learned with this device.

The detector consists of a cryogenic fluid, an expansion system, and usually a magnetic field. The expansion system, which typically involves a piston and bellows arrangement, is used to suddenly reduce the pressure on the chamber liquid. The liquid is initially maintained at a pressure above the equilibrium vapor pressure curve. Following a sufficiently rapid expansion, it is left in a “superheated” condition, and bubbles will form around any nucłeation centers in the liquid. A charged particle will produce delta rays in the liquid, and the delta rays in turn can produce large numbers of ion pairs in a small volume. The recombination of these ion pairs produce a heat spike, which is thought to be responsible for bubble formation.