Notes on 'particle detectors'

The authors examine the theory of 'particle detectors' in quantum field theory on curved space-times. The historical background of the subject is discussed and then an example is given to show that an observer accelerating uniformly through the Minkowski vacuum can carry a detector which remains unexcited. The notion of a family of natural detectors for any given observer (based on an appropriate definition of rigidity) is introduced, and the response of such detectors is investigated. The theory is illustrated by consideration of a rotating detector in flat space-time. An extensive discussion is given of the radiation effects arising both from the walls of the detector and from the interaction with the external field. These effects have, in the past, led to some confusion in the interpretation of detector response; the authors clarify this interpretation here.