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Ce differently (0, 0.01, 0.1, 1, 2 and 5% with respect to Mg) doped LiMgAlF 6 ceramics were synthesized by the spark plasma sintering (SPS) method. In photoluminescence (PL), emission bands appeared at 300 nm with 30 ns day time, and these emission properties were almost the same in scintillation under X-ray irradiation. Further, thermally stimulated luminescence (TSL) was observed after X-ray irradiation, and the primary glow peak temperature was 160 °C with a lower detection limit of ∼10 mGy. • Ce-doped LiMgAlF 6 ceramics were prepared by the spark plasma sintering method. • Photoluminesence and scintillation properties were investigated. • Thermally stimulated luminescence properties were evaluated. [ABSTRACT FROM AUTHOR]

Various fundamental characteristics of Y2O3 ceramics, such as optical transmittance, reflectivity, absorption coefficient, refractive index, and dielectric constant, were investigated. Furthermore, in order to evaluate the possible application of this material as γ-ray scintillator, other radiation responses, like the α-ray excited emission spectrum, the γ-ray excited pulse height spectrum, the light yield, the nonproportionality, the energy resolution, and the γ-ray excited scintillation decay curves were obtained. The light yield of Y2O3 ceramics was evaluated in about 1.13 times higher than that of Bi4Ge3O12 (BGO):Ce single crystals and was estimated in 9300 photon/MeV. The nonproportionality measurements showed a good proportionality. The scintillation decay curve could be fitted by an exponential function characterized by a fast component of about 34 ns. [ABSTRACT FROM AUTHOR]

Nominally Nd 0.1, 0.5, 1 and 2% doped YAlO 3 (YAP) single crystals were synthesized by the floating zone method to evaluate their optical and scintillation properties. In photoluminescence (PL), all the samples showed sharp emission lines in the UV-VIS region, and the PL quantum yield in this spectral range was 5–15%. The PL decay time of the 4F 7/2 → 4I 9/2 transition was evaluated to be around 150 ms. In scintillation emission spectrum under X-ray irradiation, several emission lines due to the 4f-4f transitions of Nd3+ were observed in the UV-VIS range. These emissions was found to consist of two decay constants of a few μs and 100–150 ms. When irradiated with 662 keV γ-rays from 137Cs, the Nd 0.1% doped sample exhibited the highest scintillation light yield of 12500 ph/MeV determined by pulse height analysis. • Undoped and Nd differently doped YAP crystal scintillators were prepared. • Optical and scintillation properties of the undoped and Nd-doped YAP were evaluated. • Nd 0.1% doped YAP showed a clear photoabsorption peak in the pulse height spectrum. • The scintillation light yield of Nd 0.1% doped YAP was 12500 ph/MeV. [ABSTRACT FROM AUTHOR]

Abstract In this research, we found that some undoped crystals (LiAlO 2 and LiGaO 2) show pulse shape discrimination (PSD) capabilities, and we report some basic scintillation and PSD properties of these crystals. These two crystals show scintillation spectrum with an emission peak at around 330 nm, and the spectral shapes of the two were identical. The scintillation decay curves consist of decay components on the order of micro-second for both the crystals under X-ray excitation, and the decay times were specify values. When we irradiated the samples with neutrons from 252Cf and γ -rays from 60Co, we found that decays vary for signals generated by neutron and γ -rays. A two-dimensional histogram of pulse heights of the slow and fast components for LiAlO 2 and LiGaO 2 clearly showed neutron and γ -ray events separated in the two-dimensional histogram indicating material's capacity for PSD. [ABSTRACT FROM AUTHOR]

Abstract 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. [ABSTRACT FROM AUTHOR]

Abstract 30BaO–(70- x)TiO 2 – x GeO 2 (x = 50, 55, 60; BTG) glass and glass-ceramics samples were prepared by a melt-quenching method, and the optical and X-ray induced scintillation properties were investigated. In this study, we prepared twelve different samples: three different compositions (BTG x ; x = 50, 55 and 60), two different melting temperatures (1250 and 1550 °C), and with/without crystallization process. The crystallization phenomenon was confirmed by XRD analysis. In photoluminescence spectra, only one broad emission peak at 520 nm was observed in the glass samples, while another peak was observed in glass-ceramic samples at 450 nm in addition to 520 nm peak. The similar tendency was also observed in X-ray induced scintillation spectra. According to the crystallization, the scintillation efficiency was enhanced. Highlights • Optical properties of 30BaO–(70- x)TiO 2 – x GeO 2 (x = 50, 55, 60) glass-ceramics treated by different temperatures are reported. • Scintillation properties of 30BaO–(70- x)TiO 2 – x GeO 2 (x = 50, 55, 60) glass-ceramics are demonstrated. • The glass-ceramic samples showed scintillation peaking around 520 nm. • According to the crystallization, scintillation light yield was enhanced. [ABSTRACT FROM AUTHOR]

Abstract Eu:BaFBr is typically used in a ceramic form for imaging plate, and it has not been commonly studied in a single crystal form and for scintillator applications. In this study, we prepared Eu:BaFBr single crystal by the Bridgeman method and then evaluated the scintillation properties. The crystal showed an intense scintillation emission spectrum under X-ray excitation with a peak appeared at 395 nm due to the 5d-4f transitions of divalent Eu ion, and the scintillation decay time under X-ray irradiation was 1.4 μs. When we irradiated with γ-rays by 137Cs, a clear photoabsorption peak was observed in the pulse height spectrum, and the scintillation light yield was estimated to be 27000 ph/MeV. By using various radio isotopes, we investigated the relation between peak channels of photoabsorption peak and γ-ray energy, and we confirmed a linear relationship from 60 keV to 1.27 MeV. To the best of our knowledge, this is the first report of Eu:BaFBr crystal demonstrating as a scintillator for γ-ray detections. Highlights • Scintillation properties of Eu-doped BaFBr crystal is investigated. • Emission due to Eu2+ 5d-4f transition is confirmed. • Gamma-ray responses of Eu-doped BaFBr is examined. • Eu-doped BaFBr shows a high scintillation light yield of 27000 ph/MeV. [ABSTRACT FROM AUTHOR]

Abstract We have compared the trap states of electrons and holes responsible for the thermoluminescence of Y 3 Al 5 O 12 (YAG):Ce crystals and ceramics after X-ray or UV irradiation. In the case of X-rays, electrons and holes are trapped at different sites, whereas UV irradiation affords the photo-ionization of Ce3+ ions, in which electrons are trapped on certain sites and the holes afford Ce4+ ions. We found a dominant band in the thermoluminescence spectra after irradiation, attributed to the 5d–4f transitions of Ce3+ ions. The glow curves in both cases have peaks present at the same temperatures and have similar relative intensities. These results indicate that both the trap states and thermoluminescence processes are similar between the types of irradiation. [ABSTRACT FROM AUTHOR]

The undoped ScAlMgO 4 crystal was synthesized by the Floating Zone (FZ) method, and we evaluated the optical and scintillation properties. The transmittance spectrum showed the absorption edge around 200 nm. VUV-excited emission/excitation spectrum was characterized at a synchrotron facility (UVSOR). Our experiment revealed that the emission was around 400 nm by 200 nm excitation, and the excitation band was 170–210 nm for the latter emission peak. The decay time characterized by 280 nm excitation was 8.3 and 43 ns. Under X-ray irradiation, an emission was observed around 400 nm as for VUV excitation, and the latter decay time constants were 0.23 and 2.2 μs. In addition, the afterglow level at 20 ms after X-ray irradiation was around 0.1% of the intensity during irradiation. [ABSTRACT FROM AUTHOR]

Very low amount of Eu and alkali metal (Na, K, Rb and Cs) co-doped LiCaAlF 6 crystal scintillators were prepared by using the micro-pulling down method to investigate the origin of the light yield enhancement and the fast luminescence of LiCaAlF 6 -based scintillators. In X-ray and α-ray induced scintillation spectra, the host and Eu 2+ 5d-4f transition emission appeared around 300–500 nm as a broad shape and 370 nm as a sharp line, respectively. At a synchrotron facility (UVSOR), the excitation spectra under vacuum ultra violet (VUV) photons excitation were investigated, and the results confirmed new excitation bands around 80–90 nm as well as the band gap of LiCaAlF 6 (~113 nm). Fast luminescence with the lifetime of few ns was confirmed in K, Rb and Cs doped samples under VUV and X-ray excitations. The detector property was tested, and K co-doping improves the pulse shape discrimination performance. [ABSTRACT FROM AUTHOR]

We analyzed the effects of the excitation density or linear energy transfer (LET) on the scintillation temporal profiles of Gd 2 SiO 5 (GSO):Ce by using pulsed ion beams of 20 MeV H + , 50 MeV He 2+ , and 220 MeV C 5+ . The rise was faster at higher LET, while the decay was similar at largely different LETs. The LET effects on the rise are explained in terms of the competition between the quenching owing to the interaction between the 6 P J excited states at neighboring Gd 3+ ions and the energy transfer to Ce 3+ ions. [ABSTRACT FROM AUTHOR]

Optical and scintillation properties of TGG (Tb 3 Ga 5 O 12 ) and TSAG (Tb 3 Sc 2 Al 3 O 12 ) crystals were investigated, and capabilities to be used as a scintillator screen were demonstrated. In photoluminescence (PL) spectra, some emission lines due to Tb 3+ 4f-4f transitions appeared from 500 to 700 nm. PL quantum yields of TGG and TSAG were 6.5% and 50.9%, respectively. When irradiated by X-rays, these crystals showed intense scintillation, and the emission wavelengths were the same as those in PL spectra. The scintillation decay times of TGG and TSAG were 94 and 678 μs, respectively. Further, we have demonstrated X-ray imaging using both TSGG and TSAG crystal plates and confirmed a capability as scintillator screens. [ABSTRACT FROM AUTHOR]

Optical and scintillation properties of nondoped and Eu 3% doped SrI 2 crystals grown by the Vertical Bridgman method were investigated. Eu-doped crystal showed an intense single band emission at 430 nm due to the Eu 2+ 5d-4f transitions in both photoluminescence and scintillation while the nondoped crystal had a complex spectral shape. The latter emission consists of mainly four bands: 360 nm, 540 nm, 410 nm and 430 nm. The origins of 360 nm and 540 nm were self-trapped exciton and unexpected impurity, respectively. The origins of 410 and 430 nm lines were ascribed to F center in different I sites. Under 137 Cs γ-ray irradiations, both crystals showed a clear photoabsorption peak. The scintillation light yields of the nondoped and Eu-doped SrI 2 resulted 33,000 ph/MeV and 82,000 ph/MeV, respectively. The energy resolution at 662 keV of Eu-doped was 4% while that of the non-doped SrI 2 was 8%. [ABSTRACT FROM AUTHOR]

Radiophotoluminescence (RPL) is one luminescence phenomenon in which a new luminescent center is generated in a material by interaction with ionizing radiation. The luminescence center, so-called RPL center, can be observed by a conventional photoluminescence technique, and the luminescence intensity is proportional to the number of RPL centers, which is proportional to the radiation energy deposited and accumulated in the material. Therefore, RPL can be used for radiation dosimetry. Since discovery of RPL in the middle of the 20th century to the present, it has found successful industrial application in personnel dosimetry and is still one of the most reliable and actively used dosimetry techniques. This paper clarifies the fundamental RPL properties to be considered for radiation measurements and reviews the applications and recently reported RPL materials. • In RPL phenomenon, interaction with ionizing radiation forms a new luminescent center. • Fundamental RPL properties for radiation dosimetry are discussed. • Conventional applications of RPL are discussed. • New materials and knowledge of RPL will advance the RPL technologies. [ABSTRACT FROM AUTHOR]

In solid state ionizing radiation detectors, mainly two types of luminescent materials, scintillators and dosimeter materials, have been investigated for a long time. The former one transduces the energy of high energy ionizing radiation (keV–GeV) to thousands of UV-visible photons immediately and the latter storages energies under radiation exposure. After the excitation by visible photons (OSL) or thermal energies (TSL), dosimeter materials release the storage energies by UV-visible emission. In this work, Ce-doped CaF 2 , Eu-doped LiCaAlF 6 , Ce-doped LiCaAlF 6 , and Pr-doped LuAG were evaluated on their scintillation, OSL, and TSL properties. In Ce-doped CaF 2 , Eu-doped LiCaAlF 6 , and Pr-doped LuAG, scintillation and dosimeter properties showed a complementally relation while Ce-doped LiCaAlF 6 exhibited different properties. [ABSTRACT FROM AUTHOR]

Optical absorption and photoluminescence properties of Sn 2 + , Sb 3 + , and Te 4 + -doped zinc borate glasses are examined. The obtained ns 2 -type center-doped glasses prepared by non-quenching method using glassy carbon crucible show different absorption and photoluminescent (PL) properties compared with those prepared by a conventional rapid-quenched method. The optical absorption edges red-shift with increasing amount of ns 2 -type center. There is a linear relationship between the optical absorption edge and the PL excitation band among Sn 2 + , Sb 3 + , and Te 4 + centers. Although these 5 s 2 emission centers possess the same electron configuration, Sn 2 + center possessing the longest decay constant exhibits the highest intensity and quantum efficiency. [ABSTRACT FROM AUTHOR]

Ce-doped 34Li 2 O–5MgO–10Al 2 O 3 –51SiO 2 glass was prepared by the conventional melt quenching method and compared with commercially available material, Li-glass (Saint Gobain) on their optical and scintillation properties. They exhibited 80% transmittance at wavelength longer than 350 nm. Photoluminescence (PL) emission peaks of the prepared glass and Li-glass resulted 385 and 420 nm, respectively. Temperature dependences of PL of these materials were examined from 25 to 300 K and they showed different responses. In X-ray induced scintillation spectra, emission peaks were similar to those in PL. Primary scintillation decay time of the prepared glass was largely faster than the conventional Li-glass and resulted few ns. In thermally stimulated luminescence glow curve, the prepared glass showed a deeper trap and it showed better afterglow property. Finally, 252 Cf neutron induced light yield was evaluated and the light yield of the prepared glass was around 10% of that of Li-glass. [ABSTRACT FROM AUTHOR]

We measured temporal profiles of the scintillation of Ce-doped LiCaAlF 6 scintillator crystals at different linear energy transfers (LETs). Based on the comparison of high-LET temporal profiles with those at low LET, a fast component was observed only at low LET. The disappearance of the fast component at high LET is tentatively ascribed to the quenching of excited states at crystal defects owing to the interaction between excited states via the Auger process. In addition, the rise and the initial decay behavior were dependent on the LET. This LET-dependent behavior is explained by an acceleration process and a deceleration process in energy transfer at high LET. The LET-dependent temporal profiles provide the basis for a discrimination technique of gamma-ray and neutron detection events using these scintillators based on the nuclear reaction, 6 Li(n,α)t. [ABSTRACT FROM AUTHOR]

The organic liquid scintillators based on the emissive polymers are reported. A series of conjugated polymers containing organoboron complexes which show the luminescence in the near infrared (NIR) region were synthesized. The polymers showed good solubility in common organic solvents. From the comparison of the luminescent properties of the synthesized polymers between optical and radiation excitation, similar emission bands were detected. In addition, less significant degradation was observed. These data propose that the organoboron conjugated polymers are attractive platforms to work as an organic liquid scintillator with the emission in the NIR region. [ABSTRACT FROM AUTHOR]

Solid state organic scintillators, such as anthracene, stilbene, and p-terphenyl were investigated on their basic scintillation properties and neutron–gamma discrimination capabilities. Scintillation wavelengths under X-ray irradiation of anthracene, stilbene, and p-terphenyl were 445–525, 400–500, and 350–450 nm, respectively. Scintillation light yields of anthracene, stilbene, and p-terphenyl under 137 Cs gamma-ray irradiation were 20100, 16000, and 19400 ph/MeV, respectively. Neutron and gamma-ray events discrimination capabilities were examined and anthracene exhibited the best figure of merit among three organic scintillators. [ABSTRACT FROM AUTHOR]

Yttrium co-doping was attempted to enhance dosimeter performance of Eu doped LiCaAlF 6 crystal. Eu doped and Eu, Y co-doped LiCaAlF 6 were prepared by the micro-pulling-down technique, and their dosimeter characteristics such as optically stimulated luminescence (OSL) and thermally stimulated luminescence (TSL) were investigated. By yttrium co-doping, emission intensities of OSL and TSL were enhanced by some orders of magnitude. In contrast, scintillation characteristics of yttrium co-doped crystal such as intensity of prompt luminescence induced by X-ray and light yield under neutron irradiation were degraded. [ABSTRACT FROM AUTHOR]

Nd 0.1, 0.5, 1, and 3 mol% doped YLiF 4 crystalline scintillators were prepared by Tokuyama Corp. and their optical and scintillation properties from vacuum ultraviolet (VUV) to near infrared (NIR) wavelengths were investigated. 4f–5d absorption bands appeared in VUV and several absorption bands due to 4f–4f transition were observed in visible-NIR wavelengths. Nd 3+ 5d–4f emission was observed around 180 nm under 160 nm excitation and intense line due to 4 F 3/2 → 4 I 11/2 at 1064 nm appeared under 500 nm excitation. In X-ray induced radioluminescence, both VUV and NIR emissions were observed. Scintillation decay times of VUV emission was 40–80 ns while that of 4f–4f ones at visible wavelength were around 12–15 μs. When 252 Cf neutron was irradiated, VUV scintillation light yield resulted around 90 ph/n. [ABSTRACT FROM AUTHOR]

Photoluminescence (PL), photo-stimulated luminescence (PSL), and thermoluminescence (TL) properties of a Ce-doped CaB 2 O 4 crystal were studied. The Ce-doped crystal was prepared by the simple solidification method using a Pt crucible under nitrogen atmosphere. A PL emission band in the 350–370 nm wavelength range was obtained under excitation at 325 nm owing to the 5d (t 2g )–4f ( 2 F 5/2 , 2 F 7/2 )-allowed transition of the Ce 3+ emission center. The fluorescence quantum efficiency and the decay time of Ce 3+ were estimated to be about 70% and 29 ns, respectively. The 5d–4f emission band of Ce 3+ also appeared in the 350–370 nm wavelength range in the TL and PSL spectra. Good linear TL and PSL responses were observed in the 1–1000 mGy and 1–10,000 mGy X-ray dose range, respectively. [ABSTRACT FROM AUTHOR]

CdF 2 single crystal was prepared by Tokuyama Corp. with the μ-PD method to investigate Auger free luminescence of this material. From optical transmittance spectrum, bandgap wavelength was around 280 nm. In X-ray induced radioluminescence spectrum, emission lines appeared around 350 nm and 420 nm. Excitation wavelength was investigated and excitation peak was around 250 nm. Photoluminescence and scintillation decay times were evaluated and decay time was few ns. Temperature dependence of X-ray induced radioluminescence was compared with conventional BaF 2 scintillator and scintillation of CdF 2 decreased when the temperature increased. Consequently, scintillation of CdF 2 is possibly emission at color centers or exciton related one. [ABSTRACT FROM AUTHOR]

Scintillation and optical stimulated luminescence of Ce 0.1–20% doped CaF 2 crystals prepared by Tokuyama Corp. were investigated. In X-ray induced scintillation spectra, luminescence due to Ce 3+ 5d–4f transition appeared around 320 nm with typically 40 ns decay time. By 241 Am 5.5 MeV α-ray irradiation, 0.1% doped one showed the highest scintillation light yield and the light yield monotonically decreased with Ce concentrations. Optically stimulated luminescence after X-ray irradiation was observed around 320 nm under 550 or 830 nm stimulation in all samples. As a result, intensities of optically stimulated luminescence were proportional to Ce concentrations. Consequently, scintillation and optically stimulated luminescence resulted to have a complementary relation in Ce-doped CaF 2 system. [ABSTRACT FROM AUTHOR]

The crystals of Tm doped and Tm-Sc co-doped Lu 3 Al 5 O 12 (LuAG) grown by the floating zone (FZ) method were examined for their optical and scintillation properties. In transmittance spectra, strong absorption lines due to Tm 3+ 4f–4f transitions were observed. X-ray excited radioluminescence spectra were measured and broad and sharp emission peaks were detected. The former one was attributed to Sc 3+ and the latter one was due to Tm 3+ 4f–4f transitions. Scintillation yield enhancement due to Sc co-doping was observed by means of 137 Cs pulse height spectra. Scintillation decay times were several tens of μs under pulse X-ray excitation. [ABSTRACT FROM AUTHOR]

Optical, scintillation properties, optical stimulated luminescence, and thermally stimulated luminescence of Ce 1, 3, and 5% doped and Eu 1, 1.5, and 2% doped LiCaAlF 6 crystals fabricated by Tokuyama Corp. were investigated. In transmittance, absorption was proportional to dopant concentrations and typical optical quantum yield of Ce and Eu-doped LiCaAlF 6 were 40 and 100%, respectively. Scintillation wavelength and decay time profiles were investigated under X-ray irradiation. Ce 3+ and Eu 2+ 5d-4f luminescence appeared around 300 nm and 370 nm with typical decay time of 40 ns and 1.5 μs, respectively. Optically stimulated luminescence of Ce-doped ones appeared under 405 nm stimulation with detectable intensity while those of Eu doped ones were quite weak. Thermally stimulated luminescence of Ce- and Eu-doped LiCaAlF 6 were enough strong and they exhibited good response function from 1 to 1000 mGy exposure. [ABSTRACT FROM AUTHOR]

Nd 1% doped complex garnet scintillators were prepared by Furukawa and their optical and scintillation properties were investigated on a comparison with previously reported Nd-doped YAG. Chemical compositions of newly developed complex garnets were Lu 2 Y 1 Al 5 O 12 , Lu 2 Y 1 Ga 3 Al 2 O 12 , Lu 2 Gd 1 Al 5 O 12 , Lu 2 Gd 1 Ga 3 Al 2 O 12 , Gd 1 Y 2 Al 5 O 12 , Gd 1 Y 2 Ga 3 Al 2 O 12 , and Gd 3 Ga 3 Al 2 O 12 . They all showed 50–80% transmittance from ultraviolet to near infrared wavelengths with several absorption bands due to Gd 3+ or Nd 3+ 4f–4f transition. In X-ray induced radioluminescence spectra, all samples exhibited intense lines at 310 nm due to Gd 3+ or 400 nm due to Nd 3+ depending on their chemical composition. Among them, the highest scintillation light yield was achieved by Lu 2 Y 1 Al 5 O 12 . Typical scintillation decay times of them resulted 1.5–3 μs. Thermally stimulated glow curve after 1 Gy exposure and X-ray induced afterglow were also investigated. [ABSTRACT FROM AUTHOR]

Positive hysteresis and radiation tolerance to high-dose radiation exposure were investigated for Ce 1% and 3% doped Gd 3 (Al, Ga) 5 O 12 (Ce:GAGG) crystal scintillator on comparison with other garnet scintillators such Ce:YAG, Ce:LuAG, Pr:LuAG, and ceramic Ce:GAGG. When they were irradiated by several Gy 60 Co γ-rays, Ce 1% doped GAGG crystal exhibited ∼20% light yield enhancement (positive hysteresis). This is the first time to observe positive hysteresis in Ce doped GAGG. On the other hand, other garnet materials did not show the positive hysteresis and their light yields were stable after 800 Gy irradiation except Pr:LuAG. The light yield of Pr:LuAG decreased largely. When irradiated Ce:GAGG which showed positive hysteresis was evaluated in Synchrotron facility (UVSOR), new excitation band was created around 60 nm. [ABSTRACT FROM AUTHOR]

Scintillation properties associated with intrinsic lattice defects of undoped Y 3 A 5 O 12 (YAG) and Lu 3 A 5 O 12 (LuAG) transparent ceramics and single crystals are compared. The ceramics excited with X-ray demonstrated relatively low emission intensity when compared with that of the single crystals. Decay times of the ceramics and the single crystals were similar. These parameters were approximately 430 ns (YAG ceramic), 460 ns (YAG single crystal), 30 ns and 1090 ns (LuAG ceramic), and 25 ns and 970 ns (LuAG single crystal). According to the pulse height spectra recorded under 137 Cs gamma-ray irradiation, the scintillation light yield of the both ceramics were about 2950 ± 290 ph/MeV. However, the single crystals had greater kight yield of about about 14,300 ± 1430 ph/MeV for YAG and 8350 ± 830 ph/MeV for LuAG. [ABSTRACT FROM AUTHOR]

Highlights: [•] Optical and scintillation properties of ceramic Yb-doped Lu2O3 with different Yb concentrations were evaluated. [•] Yb 0.3% doped sample showed the highest scintillation light yield of 500ph/MeV. [•] Scintillation decay time of Yb:Lu2O3 was typically around 1ns. [Copyright &y& Elsevier]

Functional possibilities of Pr:LuAG single crystal covered with plastic scintillators are demonstrated. Shift of luminescence wavelength of the hybrid scintillators towards the region of higher spectral sensitivity of photodetectors and radiation responses of the hybrid scintillators were investigated. The Pr:LuAG sample coated with bis-MSBPVD showed the better light output and energy resolution than the Pr:LuAG itself. Light output was increased up to 55% and energy resolution was also improved to 6.5%@662 keV using APD (Hamamatsu S8664-8220). In the case of MPPC (Hamamatsu S10362_33_050 3600 pixel-type), light output was increased up to 35% and energy resolution was also improved to 9.8%@662 keV. Decay curve of the Pr:LuAG sample coupled with the WLS was also measured and successfully modeled. [ABSTRACT FROM PUBLISHER]

Abstract: Positive hysteresis and radiation tolerance to high-dose radiation exposure were investigated for Ce 0.5, 1, and 1.5%-doped Gd2SiO5 (GSO) and for Zr co-doped GSO with the same Ce concentrations (GSOZ). When they were irradiated by 200–800 Gy 60Co in 200 Gy steps, all Ce-doped GSO samples exhibited light yield enhancement (positive hysteresis). On the other hand, the light yield of GSOZ decreased greatly. Ce 0.5%-doped GSO showed the highest positive hysteresis, with ∼20% light yield enhancement. When the Ce concentration was increased, the positive hysteresis became weaker. [Copyright &y& Elsevier]

Abstract: Dopant free eutectic scintillators 6LiF–SrF2 and 6LiF–CaF2 were developed by the vertical Bridgeman method for the purpose of thermal neutron detection. The molar ratio of LiF and Ca/SrF2 was 4:1 on its eutectic composition. The α-ray induced radioluminescence spectra of the scintillators showed intense emission peak at 300nm due to the emission from the self-trapped exciton in Ca/SrF2 layers. When the samples were irradiated with 252Cf neutrons, 6LiF–SrF2 and 6LiF–CaF2 exhibited the light yields of 4700 and 9400ph/n, respectively. Scintillation decay times of 6LiF–SrF2 and 6LiF–CaF2 were accepted for scintillation detectors, 90 and 250ns, respectively. [Copyright &y& Elsevier]

The crystals of 0.1, 0.5, and 1mol% Ce-doped LuLiF4 (Ce:LLF) grown by the micro-pulling down (μ-PD) method were examined for their optical and scintillation properties. Ce:LLF crystals had ~80% transparency at wavelengths longer than 300nm. In photoluminescence spectra, they demonstrated intense emission peaks at 310 and 330nm with the quantum yield of 60–90%. Ce3+ 5d–4f emission peaks were also detected at similar wavelengths of 310 and 330nm in the radioluminescence spectra obtained under X-ray excitation. According to pulse height spectra recorded under γ-ray irradiation, the absolute light yield of Ce 0.1, 0.5, and 1% were 3600±400, 3000±300, and 1700±200ph/MeV, respectively. Decay time kinetics was also inspected using a pulse X-ray equipped streak camera system. The decay time components of Ce:LLF were ∼70ns and ∼1μs for all the samples. [ABSTRACT FROM AUTHOR]

Highlights: [•] 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. [ABSTRACT FROM AUTHOR]

Abstract: High scintillation efficiency of Eu-doped LiSrAlF6 (LiSAF) and LiCaAlF6 (LiCAF) codoped with alkali metal ions has been reported in our recent studies. Thus in this paper, we demonstrated the scintillation properties of 1% Ce-doped LiSAF crystals with 1% alkali metal ions co-doping to increase the light yield and understand the scintillation mechanism. The crystals showed intense emission band corresponding to the 5d-4f transition of Ce3+, and their light yields under thermal neutron excitation were higher than that of the Ce only doped crystal. Especially, the light yield of Ce–Na co-doped crystal exceeded about two times that of Ce only doped one. [Copyright &y& Elsevier]

Abstract: Scintillators are widely used in radiation detection applications in basic science and industry. Scintillators are generally solids and consist of an emission center and a host lattice. Especially in medical applications that detect high-energy photons, the emission centers are rare-earth (RE) ions, mostly Ce3+. However, recently Pr3+ also exhibited fast 5d–4f emission and became an alternative to Ce3+. In X-ray computed tomography, a scintillation decay time on the order of microseconds is acceptable, and other rare-earth ions such as Nd3+, Eu2+, Ho3+, Er3+, and Tm3+ are candidates for the emission center. The characteristics of these inorganic materials and their advantages and disadvantages for scintillators will be discussed. [Copyright &y& Elsevier]

Abstract: Luminescence and scintillation properties of Tm3+ 0.1–15% doped CaF2 crystals were systematically investigated. The crystals were grown by a simple solidification method which allowed us to obtain single crystals conveniently. In X-ray induced radio luminescence spectra, the luminosity of the self-trapped-exciton (STE) emission of CaF2 at 270nm decreased with increasing of Tm3+ concentration. The Tm3+ 5d-4f transition based emission lines appeared at 175nm (4f115d high spin state (HS)→ 3H6) and at 165nm (low spin state (LS) to 3H6). Pulse height spectra were measured under α-ray irradiation by using vacuum ultra-violet (VUV) sensitive photomultiplier tube (PMT) R8778 and Tm3+ 0.1% doped specimen exhibited the highest light yield. [Copyright &y& Elsevier]

Abstract: Sc2O3, Y2O3 and Lu2O3 transparent ceramics were prepared by the spark plasma sintering (SPS) method. After polishing, the samples were semitransparent. Their optical transmittance was 10–40% at 500 nm which corresponded with their semi-transparency. In the X-ray induced emission spectra, a broad emission peak appeared around 335 nm in each sample. For this wavelength, scintillation decay time for Y2O3 and Sc2O3 were 22 and 48 ns, respectively. The light yield of Sc2O3, Y2O3 and Lu2O3 was 16,200, 2600, and 200 ph/5.5 MeV-alpha, respectively, which followed from the alpha-ray induced pulse height spectra. The gamma-ray induced light yield of Sc2O3 was 11,500 ph/MeV, which is 1.4 times larger than that of conventional single crystal BGO (Bi4Ge3O12) scintillator. Light yield non-proportionality and energy resolution of Sc2O3 were examined for the first time. [Copyright &y& Elsevier]

Abstract: Capability of thermal neutron detection was examined for LiCaAlF6 (LiCAF) scintillators doped with 3d-transition metal ions. Their radioluminescence spectra were measured with an 241-Am source to simulate 6Li(n, α)3H reaction. The sufficiently intense radioluminescence was observed for the Mn, Co and Cu dopants, while only a weak one was observed for Ti, V, Fe and Ni. A Mn doped LiCAF crystal, which showed the highest radioluminescence intensity, was coupled with a Si avalanche photodiode for the examination of its neutron response. It was confirmed that the average current of the photodiode clearly increased under excitation with 13.5 meV neutron flux. [Copyright &y& Elsevier]

Abstract: Eu and Rb co-doped LiCaAlF6 (LiCAF) single crystals with different dopant concentrations were grown by the micro-pulling-down method for neutron detection. Their transmittance spectra showed strong absorption bands at 200–220 and 290–350 nm, and under 241Am alpha-ray excitation, their radioluminescence spectra exhibited an intense emission peak at 373 nm that was attributed to the Eu2+ 5d–4f transition. These results were consistent with those for the Rb-free Eu:LiCAF. The highest light yield among the grown crystals was 36,000 ph/n, which was 20% greater than that of the Rb-free crystal. In addition, the neutron-excited scintillation decay times were 650–750 ns slower than that of the Rb-free Eu:LiCAF. [Copyright &y& Elsevier]

Abstract: We examined basic luminescence properties and radiation response of sodium borate glass scintillators activated with Pb2+, Cu+, Ti4+, V5+, W6+ and Yb3+ ions, respectively. These glasses had more than 80% transparency for emission wavelength range, and strong absorption bands due to the charge transition of the ions were observed. In the photoluminescence spectra, all glasses demonstrated intense emission peak in visible region, which are corresponding to the ions with s2 (Pb2+), d10 (Cu+) and d0 (Ti4+, V5+, W6+) configuration. Additionally charge transfer emission was observed in Yb3+-doped glass. When 241Am 5.5 MeV alpha-ray excited the glasses, they showed weak emission intensity because of low energy transfer efficiency from host lattice to emission center. By 241Am irradiated pulse height spectra, Cu+-doped glass demonstrated the highest scintillation output in the glasses. [Copyright &y& Elsevier]

Abstract: (Lu1 − x Tm x )2SiO5 (x = 0.001, 0.01, 0.1, 1) single crystalline scintillators were grown by the μ-PD method. In transmittance measurement, absorption bands due to Tm3+ 4f–4f transitions were observed at 260, 292, 356, 463, 680 and 790 nm and they could be ascribed to the transition from the 3H6 ground state to its excited states, 1I6, 3P6,1D2, 1G4, 3F3 and 3H4, respectively. Strong emission peak due to 1D2 → 3F4 transition of Tm3+ was shown at 453 nm under X-ray irradiation. Photoluminescence decay time constant caused by this transition were evaluated to be 11.9 μs. Tm 1% doped one exhibited the highest light yield of 3530 ± 200 photons/MeV when excited by 137Cs gamma-ray exposure. [Copyright &y& Elsevier]

Abstract: 0.1, 1, and 3% Pr (with respect to Lu) doped LuLiF4 (Pr:LuLiF4) single crystals were grown by the micro-pulling-down (μ-PD) method. Transparency of the grown crystals was higher than 70% in the visible wavelength region with some absorption bands due to Pr3+ 4f-4f transitions. Intense absorption bands related with the Pr3+ 4f-5d transitions were observed at 190 and 215 nm. In radioluminescence spectra, Pr3+ 5d-4f emissions were observed at 220, 240, 340, and 405 nm. In the pulse height spectra recorded under 137Cs γ-ray excitation, the Pr 3% doped sample showed the highest light yield of 2050 photons/MeV and the scintillation decay time of it exhibited 23 and 72 ns also excited by 137Cs γ-ray. [Copyright &y& Elsevier]

Abstract: Vacuum Ultra violet (VUV) scintillators, have a short decay time around several ns, and therefore can be used in high counting rate applications. New Nd-doped BaY2F8 VUV scintillator crystals were successfully grown by a micro-pulling down (μ-PD) method and their optical properties and radiation response were investigated. All the BaY2F8 samples with 0.5, 1, 3, 7 and 10 mol% Nd concentration had 5d-4f luminescence peaks at 185, 237 and 270 nm. Although this scintillator has low light output around 70 photons/5.5-MeV alpha, which was determined from our pulse height measurement, we found that the decay time of this crystal reached 13 ns which is a typical value for the VUV scintillators. [Copyright &y& Elsevier]

Abstract: In photoluminescence which directly excites the emission center of phosphor material is known to have a correlation between the emission wavelength and the decay time based on quantum mechanics. In scintillation phenomenon, host lattice of the material is first excited by ionizing radiation and then the excitation energy is transferred to emission centers. For the first time, we investigated the correlation between the scintillation decay and the emission wavelength by using pulse X-ray equipped streak camera system which could observe time and wavelength resolved scintillation phenomenon. Investigated materials were Ce3+, Pr3+ and Nd3+ doped oxides and fluorides which all showed 5d-4f transition based emission. As a result, we obtained the relation that τ (scintillation decay time) was proportional to the λ 2.15 (emission wavelength). [Copyright &y& Elsevier]

Highlights: [•] Ce-doped LiF–SrF2 eutectic scintillators are reported for the first time. [•] The optimum layer thickness was determined experimentally. [•] The brightest sample exhibited the light yield of 5500ph/n. [•] In scintillation decay times, both Ce3+ 5d–4f and STE emissions were observed. [ABSTRACT FROM AUTHOR]

Abstract: 1, 3, and 6mol% Nd3+ doped (YGd2)(Sc2Al2Ga)O12 transparent ceramic garnets were fabricated by the sintering to investigate their optical and scintillation properties. They were all visibly purplish and exhibited 80% transparency in wavelength longer than 300nm with several absorption bands due to Nd3+ and Gd3+ 4f–4f transitions. In photo- and radio-luminescence spectra, they showed intense emission peaks at 383 and 416nm. Photoluminescence decay time of the former resulted ∼500μs and those of the latter 400 and 900ns, respectively. Scintillation light yield was examined by using 241Am 5.5MeV α-ray and the light yield resulted ∼200photons/5.5MeV α in Nd 1mol% doped sample. [Copyright &y& Elsevier]

Abstract: We investigated scintillation properties of Yb3+-doped Y3A5O12 (YAG) transparent ceramics with different dopant concentrations. The transparency of both 0.3% and 15% Yb3+-doped exceeded 70% in the wavelength range 300–800nm, and two kinds of absorption bands due to charge transfer (CT) transition and 4f–4f forbidden transition of Yb3+ were observed around 200–250nm and 900nm, respectively. Ultraviolet luminescence caused by the CT transition between Yb3+ and O2− was observed under α-ray excitation from 241Am sealed source. The scintillation decay times were determined to be about 2.2ns (Yb 0.3%) and 1.4ns (Yb 15%) using the streak camera system equipped with pulsed X-ray source. From 241Am alpha-ray-excited pulse height spectra, the relative scintillation light yield of 0.3% and 15% Yb3+-doped ceramics was 7% and 10% compared with that of BGO commercial scintillator. [Copyright &y& Elsevier]