Chapter 3
Scintillation Detectors for Charged
Particles and Photons
P. Lecoq
3.1 Basic Detector Principles and Scintillator Requirements
3.1.1 Interaction of Ionizing Radiation with Scintillator
Material
As any radiation detector, a scintillator is an absorbing material, which has the
additional property to convert into light a fraction of the energy deposited by
ionizing radiation. Charged and neutral particles interact with the scintillator
material through the well-known mechanisms of radiation interactions in matter
described by many authors [1, 2]. Charged particles continuously interact with
the electrons of the scintillator medium through Coulomb interactions, resulting in
atomic excitation or ionization. Neutral particles will first have to undergo a direct
interaction with the nucleus producing recoil protons or spallation fragments, which
will then transfer their energy to the medium in the same way as primary charged
particles.
The rate of energy loss (−dE/dx) for charged particles is strongly energy
dependant. It is well described by the Bethe-Bloch formula (see Chap. 2) for
incoming particles in the MeV-GeV range, with atomic shell corrections at lower
energy and radiative loss corrections at higher energy. For heavy materials currently
used as scintillators with a density of 6–8 g/cm 3 , it is typically of the order of
10 MeV/cm for a minimum ionizing particle but it can be a factor up to 100 more at
very low or very high energy (radiative losses).
P. Lecoq ()
CERN, Geneva, Switzerland
e-mail: Paul.Lecoq@cern.ch
© The Author(s) 2020
C. W. Fabjan, H. Schopper (eds.), Particle Physics Reference Library,
https://doi.org/10.1007/978-3-030-35318-6_3
45
Scintillation Detectors for Charged
Particles and Photons
P. Lecoq
3.1 Basic Detector Principles and Scintillator Requirements
3.1.1 Interaction of Ionizing Radiation with Scintillator
Material
As any radiation detector, a scintillator is an absorbing material, which has the
additional property to convert into light a fraction of the energy deposited by
ionizing radiation. Charged and neutral particles interact with the scintillator
material through the well-known mechanisms of radiation interactions in matter
described by many authors [1, 2]. Charged particles continuously interact with
the electrons of the scintillator medium through Coulomb interactions, resulting in
atomic excitation or ionization. Neutral particles will first have to undergo a direct
interaction with the nucleus producing recoil protons or spallation fragments, which
will then transfer their energy to the medium in the same way as primary charged
particles.
The rate of energy loss (−dE/dx) for charged particles is strongly energy
dependant. It is well described by the Bethe-Bloch formula (see Chap. 2) for
incoming particles in the MeV-GeV range, with atomic shell corrections at lower
energy and radiative loss corrections at higher energy. For heavy materials currently
used as scintillators with a density of 6–8 g/cm 3 , it is typically of the order of
10 MeV/cm for a minimum ionizing particle but it can be a factor up to 100 more at
very low or very high energy (radiative losses).
P. Lecoq ()
CERN, Geneva, Switzerland
e-mail: Paul.Lecoq@cern.ch
© The Author(s) 2020
C. W. Fabjan, H. Schopper (eds.), Particle Physics Reference Library,
https://doi.org/10.1007/978-3-030-35318-6_3
45