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Light Sources
Published in Toru Yoshizawa, Handbook of Optical Metrology, 2015
PL results from optical excitation via absorption of photons. Many substances undergo excitation and start glowing under UV light illumination. PL occurs when a system is excited to a higher energy level by absorbing a photon and then spontaneously decays to a lower energy level, emitting a photon. When the luminescence is produced in a material by bombarding with high-speed subatomic particles such as β-particles and results in x- or γ-ray radiation, it is called radioluminescence. An example of a common radioluminescent material is the tritium-excited luminous paints used on watch dials and gun sights, which replaced the previously used mixture of radium and copper-doped zinc sulfide paints.
Scintillation Detectors
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
The mechanisms by which various materials receive energy that is later emitted as visible light has given rise to a large number of names of phenomena, such as thermoluminescence (energy received due to thermal action and emitted differently than by black-body radiation); chemoluminescence (energy received through chemical reactions); or the common photoluminescence (energy received from visible or UV light). Radioluminescence or cathodoluminescence are phenomena whereby visible light is emitted following excitation by charged particles or only by electrons (cathodoluminescence). The overall term ‘scintillation’ roughly refers to the flashes of light that appear from a scintillator during de-excitation from a higher energy level and may thus to most readers be nearly identical to radioluminescence, a fluorescence or phosphorescence due to the absorbed energy from ionizing radiation. Scintillations are generally thought of as being the near prompt, fluorescent light, while the fraction of energy emitted as phosphorescence and delayed fluorescent light is at a minimum. Scintillation light may thus be treated as a subgroup of radioluminescence where timing of the emitted light is important. There may not be a complete consensus as to whether scintillation and radioluminescence cover the same physical phenomena, but this is out of the scope of this chapter. For a detailed description of the kinetics and mechanisms of scintillators please refer to [2] and [11].
Cavitation and Light Emission
Published in Dmitry A. Biryukov, Denis N. Gerasimov, Eugeny I. Yutin, Cavitation and Associated Phenomena, 2021
Dmitry A. Biryukov, Denis N. Gerasimov, Eugeny I. Yutin
Scintillation detectors use luminescence6 of some substances under ionizing radiation; sometimes this type of luminescence is termed as radioluminescence. A high-energy particle (qama-quantum, for example) excites the medium; after that, a scintillation photon can be registered with a photo-electron multiplier or with something else. Scintillation detectors can be used as spectrometers, allowing to define the energy of ionizing particles.
Optically stimulated luminescence properties of Tl-doped NH4Cl transparent ceramics fabricated by SPS method
Published in Journal of Asian Ceramic Societies, 2021
Daichi Onoda, Hiromi Kimura, Daisuke Nakauchi, Takumi Kato, Noriaki Kawaguchi, Takayuki Yanagida
In this study, we focused on Tl-doped NH4Cl transparent ceramics as OSL phosphors. The reasons why we chose this material are as follows. First, Zeff of NH4Cl is ~14.5, which is close to that of soft human body tissues. Second, Tl-doped ammonium salts such as (NH4)2SiF6 and NH4Br were reported to exhibit a high OSL sensitivity to fast neutrons [35]; thus, we expected that Tl-doped NH4Cl would also exhibit effective OSL properties. In addition, although there have been some reports of optical properties of Tl-doped NH4Cl [36–38], the OSL properties have not been studied yet. For the above reasons, we fabricated Tl-doped NH4Cl transparent ceramics using SPS and evaluated the OSL properties. Moreover, in this work, we evaluated the properties of photoluminescence (PL) and radioluminescence (RL) in order to identify luminescence centers.