Scintillation materials and detectors that are used in many applications, such as medical imaging, security, oil-logging, high energy physics and non-destructive inspection, are reviewed. The ...fundamental physics understood today is explained, and common scintillators and scintillation detectors are introduced. The properties explained here are light yield, energy non-proportionality, emission wavelength, energy resolution, decay time, effective atomic number and timing resolution. For further understanding, the emission mechanisms of scintillator materials are also introduced. Furthermore, unresolved problems in scintillation phenomenon are considered, and my recent interpretations are discussed. These topics include positive hysteresis, the co-doping of non-luminescent ions, the introduction of an aimed impurity phase, the excitation density effect and the complementary relationship between scintillators and storage phosphors.
Storage phosphors have been used for luminescent-type dosimeters to measure radiation dose. Common storage-luminescence phenomena are optically-stimulated luminescence (OSL), thermally-stimulated ...luminescence (TSL) and radio-photoluminescence (RPL). In this paper, we review the basic mechanisms of OSL, TSL and RPL, and storage phosphor materials for practical dosimetry applications are introduced. Following these reviews, recent R&D of OSL, TSL and RPL materials is summarized.
•Optical and scintillation properties of ceramic and single crystal Ce-doped GAGG were compared.•Ceramic and crystal Ce:GAGG both showed quantum yield of 89%.•Ceramic Ce:GAGG exhibited the light ...yield of 70000ph/MeV under γ-ray excitation.•At present, ceramic GAGG is the brightest oxide scintillator.
Recent study revealed that single crystal Ce:Gd3(Al,Ga)5O12 (Ce:GAGG) showed good scintillation response under γ-ray exposure. We discover here that ceramic Ce:GAGG scintillator exhibited better performance than the single crystal counterpart. We developed Ce 1% doped ceramic and single crystal GAGG scintillators with 1mm thick and compared their properties. In radioluminescence spectra, they showed intense emission peaking at 530nm due to Ce3+ 5d–4f transition. The 137Cs γ-ray induced light yields of ceramic and single crystal resulted 70000ph/MeV and 46000ph/MeV with primary decay times of 165 and 143ns, respectively. At present, the observed light yield was the brightest in oxide scintillators.
Scintillators emit visible luminescence when irradiated with X-rays. Given the unlimited tissue penetration of X-rays, the employment of scintillators could enable remote optogenetic control of ...neural functions at any depth of the brain. Here we show that a yellow-emitting inorganic scintillator, Ce-doped Gd
(Al,Ga)
O
(Ce:GAGG), can effectively activate red-shifted excitatory and inhibitory opsins, ChRmine and GtACR1, respectively. Using injectable Ce:GAGG microparticles, we successfully activated and inhibited midbrain dopamine neurons in freely moving mice by X-ray irradiation, producing bidirectional modulation of place preference behavior. Ce:GAGG microparticles are non-cytotoxic and biocompatible, allowing for chronic implantation. Pulsed X-ray irradiation at a clinical dose level is sufficient to elicit behavioral changes without reducing the number of radiosensitive cells in the brain and bone marrow. Thus, scintillator-mediated optogenetics enables minimally invasive, wireless control of cellular functions at any tissue depth in living animals, expanding X-ray applications to functional studies of biology and medicine.
Dosimeter properties of AlN YANAGIDA, Takayuki; FUJIMOTO, Yutaka; KAWAGUCHI, Noriaki ...
Journal of the Ceramic Society of Japan,
2013, Letnik:
121, Številka:
1420
Journal Article
Recenzirano
Odprti dostop
Optical, scintillation, and dosimeter properties of AlN ceramic were reported. AlN sample was SHAPAL, a commercial product of Tokuyama Corp. for mainly a heat sink application. From ultra violet to ...near infrared wavelengths, it showed 0.02–1% transmittance with visibly translucent appearance. In photoluminescence (PL), it exhibited mainly two emission bands around 340 and 550 nm with primary decay times of 0.92 and 0.24 ns, respectively. X-ray induced radioluminescence spectrum was investigated and 340 nm peak showed high emission intensity. As a dosimeter property, thermally stimulated luminescence (TSL) was studied and glow peaks appeared at 80 and 320°C. The linearity between the irradiated dose and TSL intensity was studied and AlN ceramic exhibited a good linear response from 0.002 to 0.1 Gy.
We investigated scintillation properties of organic-inorganic layered perovskite-type compounds under gamma-ray and X-ray irradiation. A crystal of the hybrid compounds with phenethyl amine (17 × 23 ...× 4 mm) was successfully fabricated by the poor-solvent diffusion method. The bulk sample showed superior scintillation properties with notably high light yield (14,000 photons per MeV) under gamma-rays and very fast decay time (11 ns). The light yield was about 1.4 time higher than that of common inorganic material (GSO:Ce) confirmed under
Cs and
Co gamma-rays. In fact, the scintillation light yield was the highest among the organic-inorganic hybrid scintillators. Moreover, it is suggested that the light yield of the crystal was proportional with the gamma-ray energy across 122-662 keV. In addition, the scintillation from the crystal had a lifetime of 11 ns which was much faster than that of GSO:Ce (48 ns) under X-ray irradiation. These results suggest that organic-inorganic layered perovskite-type compounds are promising scintillator for gamma-ray detection.
Eu-doped SrAl2O4 (Eu:SrAl2O4) crystals are prepared by a floating zone (FZ) method. In photoluminescence (PL), an intense broad emission peak around 510nm due to 5d-4f transition of Eu2+ appear under ...excitation at 250–450nm. The PL decay time constants are about 800ns due to the 5d-4f transitions of Eu2+. In the nondoped sample, emission peaks around 480 and 560nm are observed upon excitation at 316nm. The X-ray induced scintillation spectra also show an intense broad emission peak around 510nm, and the decay time constants are approximately 500ns. In the pulse height spectra of the 2.5% Eu:SrAl2O4 crystal, the absolute light yield is ~46,000ph/MeV. In thermally stimulated luminescence (TSL) after X-ray irradiation, strong TSL glow peaks are observed at 120 and 400°C. In optically stimulated luminescence (OSL) after X-ray irradiation, emission peaks are observed around 510nm while exposing the samples to the stimulation light at 800nm.
The Nd-doped LaMgAl11O19 single crystals were synthesized by the floating zone method, and the photoluminescence and scintillation properties were evaluated. Under X-ray irradiation, several sharp ...emission peaks due to the 4f–4f transitions of Nd3+ were observed at 900, 1060, and 1340 nm in the near-infrared range, and the decay curves show the typical decay time for Nd3+. The samples show good afterglow properties comparable with practical X-ray scintillators. The 1% and 3% Nd-doped LaMgAl11O19 samples show a good linearity in the dynamic range from 6–60,000 mGy/h.
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