(3) Interaction of high energy photons with matter - LUTH

short: "Scintillators"
Scintillation Detectors
When atoms in scintillators are excited by high energy particles, a
part of the excitation energy is emitted as low energy (e.g. visible)
photons. These photons can be measured to determine the energy
deposited into the scintillator.
Primary cosmic rays can excite atoms directly, X-rays or gammarays
interact via photoionisation, Compton effect or pair
production in the scintillator, producing high energy electrons.
These produce photons in the scintillator that can be detected with
photomultiplier tubes.
Materials used are NaI or CsI, organic materials (also liquid!) or
plastics.
Scintillators are often used in cosmic ray detectors, because they
can be made compact and resistent. They are also used for X-ray
detection at energies > 20 keV.
A. Zech, Instrumentation in High Energy Astrophysics
taken from:
www.ast.leeds.ac.uk/haverah
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