Cherenkov Detector vs Scintillation Detector

Cherenkov Detectors

A Cherenkov detector is a particle detector, which is based on detection of Cherenkov radiation (visible light or UV photons). In contrast to a scintillation counter the light production is instantaneous. Typical scintillator detectors have a decay time measured in microseconds while Cherenkov radiation is nearly instantaneous and with fast pulse processing equipment can be measured in picoseconds. Cherenkov counters are used mainly for the particle identification, i.e. for the determination of particle masses. Cherenkov counters contain two main elements:

The Cherenkov radiation, which is produced in the radiator, is electromagnetic radiation emitted when a charged particle (such as an electron) moves through a dielectric medium faster than the phase velocity of light in that medium. Particles exceeding the phase velocity of light result in polarization along the axis of motion creating a dipole field. When this field collapses, an electromagnetic pulse (Cherenkov radiation) is emitted in the forward direction.

Cherenkov radiation is commonly produced in dielectric materials through Compton electrons or pair-production electrons and positrons. The intensity of light produced by this process is much less than that of luminescence (the basis for scintillation detector operation) requiring more sensitive optical photon detection equipment such as low light photo-multiplier tubes (PMT). Cherenkov counters may be classified as either imaging or threshold types, depending on whether they do or do not make use of Cherenkov angle (θ) information. In the simple case of a threshold detector the mass-dependent threshold energy allows the discrimination between a lighter particle (which does radiate) and a heavier particle (which does not radiate) of the same energy or momentum. Imaging counters may be used to track particles as well as identify them. Although devices using Cherenkov radiation are often thought of as particle identification (PID) detectors, in practice, they are widely used over a much broader range of applications; including:

  • fast particle counters
  • hadronic particle identification
  • tracking detectors performing complete event reconstruction.

Scintillation Counters

scintillation counter or scintillation detector is a radiation detector which uses the effect known as scintillation. Scintillation is a flash of light produced in a transparent material by the passage of a particle (an electron, an alpha particle, an ion, or a high-energy photon). Scintillation occurs in the scintillator, which is a key part of a scintillation detector. In general, a scintillation detector consists of:

  • Scintillator. A scintillator generates photons in response to incident radiation.
  • Photodetector. A sensitive photodetector (usually a photomultiplier tube (PMT), a charge-coupled device (CCD) camera, or a photodiode), which converts the light to an electrical signal and electronics to process this signal.

The basic principle of operation involves the radiation reacting with a scintillator, which produces a series of flashes of varying intensity. The intensity of the flashes is proportional to the energy of the radiation. This feature is very important. These counters are suited to measure the energy of  gamma radiation (gamma spectroscopy) and, therefore, can be used to identify gamma emitting isotopes.

References:

Radiation Protection:

  1. Knoll, Glenn F., Radiation Detection and Measurement 4th Edition, Wiley, 8/2010. ISBN-13: 978-0470131480.
  2. Stabin, Michael G., Radiation Protection and Dosimetry: An Introduction to Health Physics, Springer, 10/2010. ISBN-13: 978-1441923912.
  3. Martin, James E., Physics for Radiation Protection 3rd Edition, Wiley-VCH, 4/2013. ISBN-13: 978-3527411764.
  4. U.S.NRC, NUCLEAR REACTOR CONCEPTS
  5. U.S. Department of Energy, Instrumantation and Control. DOE Fundamentals Handbook, Volume 2 of 2. June 1992.

Nuclear and Reactor Physics:

  1. J. R. Lamarsh, Introduction to Nuclear Reactor Theory, 2nd ed., Addison-Wesley, Reading, MA (1983).
  2. J. R. Lamarsh, A. J. Baratta, Introduction to Nuclear Engineering, 3d ed., Prentice-Hall, 2001, ISBN: 0-201-82498-1.
  3. W. M. Stacey, Nuclear Reactor Physics, John Wiley & Sons, 2001, ISBN: 0- 471-39127-1.
  4. Glasstone, Sesonske. Nuclear Reactor Engineering: Reactor Systems Engineering, Springer; 4th edition, 1994, ISBN: 978-0412985317
  5. W.S.C. Williams. Nuclear and Particle Physics. Clarendon Press; 1 edition, 1991, ISBN: 978-0198520467
  6. G.R.Keepin. Physics of Nuclear Kinetics. Addison-Wesley Pub. Co; 1st edition, 1965
  7. Robert Reed Burn, Introduction to Nuclear Reactor Operation, 1988.
  8. U.S. Department of Energy, Nuclear Physics and Reactor Theory. DOE Fundamentals Handbook, Volume 1 and 2. January 1993.
  9. Paul Reuss, Neutron Physics. EDP Sciences, 2008. ISBN: 978-2759800414.

See above:

Cherenkov Detectors