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Coincidence method

In particle physics, the coincidence method (or coincidence technique) is an experimental design through which particle detectors register two or more simultaneous measurements of a particular event through different interaction channels. Detection can be made by sensing the primary particle and/or through the detection of secondary reaction products. Such a method is used to increase the sensitivity of an experiment to a specific particle interaction, reducing conflation with background interactions by creating more degrees of freedom by which the particle in question may interact. The first notable use of the coincidence method was conducted in 1924 by the Bothe–Geiger coincidence experiment.[1]

The higher the rate of interactions or reaction products that can be measured in coincidence, the harder it is to justify such an event occurred from background flux and the higher the experiment's efficiency. As an example, the Cowan and Reines’ neutrino experiment (1956) used a design that featured a four-fold coincidence technique.[2] Particle detectors that rely on measurements of coincidence are often referred to as q-fold, where q is the number of channel measurements which must be triggered to affirm the desired interaction took place.[3] Anti-coincidence counters or "vetos" are often used to filter common backgrounds, such as cosmic rays, from interacting with the primary detection medium. For instance, such a veto is used in the gamma ray observatory COS-B. Detectors relying on coincidence designs are limited by random, chance coincidence events.[4]

  1. ^ Bonolis, Luisa. "Walther Bothe and Bruno Rossi: The birth and development of coincidence methods in cosmic-ray physics." Italian Association for the Teaching of Physics, arXiv, 29 Jul. 2011, arxiv.org/pdf/1106.1365.pdf.
  2. ^ Cowan, C. L. et al. "Detection of the Free Neutrino: a Confirmation." Science, vol. 124, no. 3212, 20 Jul. 1956, p. 448, DOI: 10.1126/science.124.3212.103.
  3. ^ Grupen, C. and B. Shwartz. Particle Detectors. Cambridge Monographs of Particle Physics, Nuclear Physics, and Cosmology 26, Second edition, Cambridge University Press, 2008, p. 64, kaf07.mephi.ru/eduroom/Books/Particle_Detectors_Grupen.pdf
  4. ^ Grupen, C. and B. Shwartz (2008). Particle Detectors. Cambridge Monographs of Particle Physics, Nuclear Physics, and Cosmology 26, Second edition, Cambridge University Press, p. 63.

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