Search

Scintillators, owing to their exceptional ability to convert high-energy ionizing radiation into visible light, are the core component of X-ray radiography. However, conventional single-crystal scintillators are inadequate to satisfy the modern social and scientific demands. So, the development of novel scintillator materials is imminent. Herein, a series of Na 5 Lu 9- x Gd x F 32 :Ce3+ glass-ceramics (GCs) scintillators were elaborated by an exercisable and low-cost method. Benefiting from the proper introduction of Al powder and Gd3+, as well as the crystallization of Na 5 Lu 9- x Gd x F 32 nanocrystal (NCs) after heat treatment, luminescence excited by ultraviolet and X-ray of the sample is enhanced significantly. The integrated X-ray excited luminescence intensity of the representative sample can reach up to 128% of that of Bi 4 Ge 3 O 12. More importantly, the sample has excellent irradiation stability that is almost undamaged even exposed to high-energy X-ray radiation. Finally, satisfactory X-ray imaging based on the resultant sample was realized. The spatial resolution is as high as 14 lp mm−1, which exceeds that of many novel perovskite scintillators. Thus, this investigation promotes the development of low-cost, stable and high-performing Ce3+-activated GCs scintillators. • Three effective ways were designed to improve the scintillating property of the sample. • The integrated X-ray excited luminescence reaches 128% of that of Bi 4 Ge 3 O 12. • The sample is undamaged even excited by high-power (12 W) X-ray, infering outstanding irradiation stability. • Satisfactory X-ray imaging based on the sample was achieved. • The spatial resolution reaches 14 lp mm−1, exceeding that of many perovskite scintillators. [ABSTRACT FROM AUTHOR]

We synthesized an undoped La2Be2O5 single crystal by the floating zone method and investigated its scintillation properties. The synthesized sample was confirmed to have a singlephase structure of La2Be2O5 as shown by the powder X-ray diffraction pattern. The diffuse transmittance spectrum of the synthesized sample had transmittance at 80% in the range of 250-850 nm. The scintillation spectrum had a broad emission band from 280 to 600 nm, which was derived from unidentified lattice defects. In the scintillation decay profile, the obtained decay time constants were 1.1, 6.2, and 386 ns. From pulse height spectra, the light yield of the La2Be2O5 single crystal was 1000 photons/MeV. In afterglow profiles, the afterglow level was 42.9 ppm. [ABSTRACT FROM AUTHOR]

The paper presents the results of a comprehensive study of the structural-phase composition, morphology, optical, luminescent, and scintillation characteristics of thick ZnO films fabricated by magnetron sputtering. By using a hot ceramic target, extremely rapid growth (~50 µm/h) of ZnO microfilms more than 100 µm thick was performed, which is an advantage for the industrial production of scintillation detectors. The effects of post-growth treatment of the fabricated films in low-temperature plasma were studied and a significant improvement in their crystalline and optical quality was shown. As a result, the films exhibit intense near-band-edge luminescence in the near-UV region with a decay time of <1 ns. Plasma treatment also allowed to significantly weaken the visible defect luminescence excited in the near-surface regions of the films. A study of the luminescence mechanisms in the synthesized films revealed that their near-band-edge emission at room temperature is formed by phonon replicas of free exciton recombination emission. Particularly, the first phonon replica plays the main role in the case of optical excitation, while upon X-ray excitation, the second phonon replica dominates. It was also shown that the green band peaking at ~510 nm (2.43 eV) is due to surface emission centers, while longer wavelength (>550 nm) green-yellow emission originates mainly from bulk parts of the films. [ABSTRACT FROM AUTHOR]

Alkali metal halides have long been used as scintillators for applications as sensors and detectors. Usually, a small amount of impurities are added to these inorganic materials to improve their luminescence efficiencies. We investigate the structures and luminescent properties of un-doped sodium iodide (NaI) and cesium-doped NaI (NaI:Cs) films deposited by thermal vacuum evaporation. Instead of using the toxic element thallium (Tl), we introduced cesium dopant into NaI. This is the first study for the NaI:Cs film excited by UV LED's ultraviolet C (273 nm, 4.54 eV). The luminescence spectra show two main peaks at 3.05 and 4.32/3.955 eV (for fused silica/B270 substrate), originating from the intrinsic defects and/or activator excited states and the intrinsic self-trapped excitons (STEs), respectively. In general, both Cs-doping and post-annealing processes enhance the luminescence performance of NaI films. [ABSTRACT FROM AUTHOR]

The article presents the results of experiments on a detection system used for detecting signals from a miniature, low-energy micro-electro-mechanical system (MEMS) X-ray source. The authors propose to use a detection based on luminescence phenomena occurring in luminophore and scintillators to record the visual signal on a CMOS/CCD detector. The main part of the article is a review of various materials of scintillators and luminophores which would be adequate to convert low-energy X-ray radiation (E < 25 keV - it is a range not typical for conventional X-ray systems) to visible light. Measurements obtained for different energies, exposure times, and different targets have been presented and analysed. [ABSTRACT FROM AUTHOR]

This study aims to determine the optimum composition of the CeBr1−xIx compound to achieve the maximum light output. It is based on calculations of the band energy structure of crystals, specifically taking into account the characteristics of the mutual location of local and band 5d states of the Ce3+ ions. The band energy structures for CeBr2I and CeBrI2 crystals were calculated using the projector augmented wave method. The valence band was found to be formed by the hybridized states of 4p Br and 5p I. The 4f states of Ce3+ are located in the energy forbidden band gap. The conduction band is formed by the localized 5d1 states, which are created by the interaction between the 5d states of Ce3+ and the 4f0 hole of the cerium ion. The higher-lying delocalized 5d2 states of Ce3+ correspond to the energy levels of the 5d states of Ce3+ in the field of the halide Cl0 (Br0) hole. The relative location of 5d1 and 5d2 bands determines the intensity of 5d–4f luminescence. The bottom of the conduction band is formed by localized 5d1 states in the CeBr2I crystal. The local character of the bottom of the conduction band in the CeBr2I crystal favors the formation of self-trapped Frenkel excitons. Transitions between the 5d1 and 4f states are responsible for 5d–4f exciton luminescence. In the CeBrI2 crystal, the conduction band is formed by mixing the localized 5d1 and delocalized 5d2 states, which leads to quenching the 5d–4f luminescence and a decrease in the light output despite the decrease in the forbidden band gap. CsBr2I is the optimum composition of the system to achieve the maximum light output. [ABSTRACT FROM AUTHOR]

We synthesized 20Lu2O3-30Ga2O3-50SiO2 glasses doped with various concentrations of Sn using a floating zone furnace equipped with Xe arc lamps. The samples showed a luminescence band around 450 nm in both photoluminescence (PL) and scintillation spectra. The origin of the luminescence was ascribed to the T1-S0 transition of Sn2+ on the basis of the luminescence wavelength and PL decay time constant. The highest scintillation intensity and PL quantum yield were observed from the 1% Sn-doped sample. The afterglow level tended to decrease with increasing Sn doping, and the afterglow levels of the 1 and 3% Sn-doped samples were comparable to that of the conventional Tl-doped CsI scintillator. The optimal concentration of Sn for the glass was estimated to be 1%. [ABSTRACT FROM AUTHOR]

A comparative study on the radioluminescence properties of Ce-doped SrAl2O4 single crystal and translucent ceramic was performed. The transmittance of the synthesized ceramic is 20-30% in the visible region. Both samples exhibit photo- and radioluminescence with a broad emission peaking at 380 nm. The decay curves are fitted by a single exponential decay function with decay time constants of 30-50 ns, consistent with the typical value of the emission for the 5d-4f transitions of Ce3+. From the pulse height spectra measured under 241Am γ-ray (59.5 keV) irradiation, the scintillation light yields are 17000 ph/MeV for the single crystal and 6100 ph/MeV for the synthesized ceramic. The scintillation light yield and afterglow of the present samples show a negative correlation. [ABSTRACT FROM AUTHOR]

Oxyfluoride glass ceramics with low toxicity, high stability and strong X-ray excited luminescence intensity are introduced as scintillating material. Herein, a series of novel NaGd 2 F 7 :xTb3+ (x = 0, 0.1, 0.2, 0.3, 0.4) were synthesized through in situ growth self-crystallization. X-ray diffraction, fourier transform infrared spectrometer and transmission electron microscopy were measured to investigate the structure and morphology of NaGd 2 F 7 glass ceramics. These investigations demonstrate that NaGd 2 F 7 nanocrystals are uniformly distributed in glass matrix with 20–30 nm diameter. Photoluminescence and X-ray excitation spectra are greatly enhanced after further thermal treatment which verify better crystallization of NaGd 2 F 7 glass ceramics. The X-ray excited luminescence of the GC2–640 sample can reach 143.8% of the commercial BGO. More importantly, the damaged material can be completely repaired by annealing at 350 °C for 30 min. Our investigation indicates that Tb-doped transparent NaGd 2 F 7 glass ceramics are potential candidates of X-ray scintillating material. [ABSTRACT FROM AUTHOR]

In order to estimate the stability of the light output of the scintillation detector, the Lu 2 SiO 5 :Ce scintillation crystals, additionally doped with Ca2+ ions at concentrations of 0 ÷ 0.4 at%, were studied. The spectra of optical absorption, gamma-luminescence, thermal luminescence, dose and temperature dependences of luminescence were measured. Gamma-luminescence in the dose range 10 - 5·107 Gy was recorded using 60Co gamma-source at the temperature range of 310–460 K. In contrast to the initial sample (non-doped with Ca), in the sample doped with 0.1 at% of Ca, an increase in the luminescence intensity was observed in the range of 390–425 nm, but further with an increase in the concentration of Ca (0.3–0.4 at%), the intensity of this band decreased to the initial level (undoped). At Ca concentrations of 0.3 and 0.4 at%, the intensity of the Ce1 center band remains practically unchanged up to a dose of 5·107 Gy. LSO crystals doped with Ce 0.1 at% and co-doped with Ca 0.1 at% can be recommended as a scintillation detector up to a gamma-dose of 105 Gy at room temperature. • Ca-codoped Lu 2 SiO 5 :Ce crystals are studied as a material for scintillation detector. • At Ca 0.1 at% an increase in the luminescence at 390–425 nm was observed. • At Ca 0.3 at% the Ce1 center emission doesn't change up to a γ-dose of 5·107 Gy. • Defect complexes completely discolor at room temperature in two days. [ABSTRACT FROM AUTHOR]

Rare-earth aluminate garnet-type double oxides have practical applications as scintillators with high luminescence yields; however, several garnet compounds are metastable phases, and those scintillation properties are yet unclear. We prepared Ce3+-doped Gd 3 Al 5 O 12 (Ce3+:GAG) as a thick-film phosphor, using laser-assisted metal–organic chemical vapor deposition, and investigated its luminescence and scintillation properties. With a deposition rate of 48 μm h−1, the Ce3+:GAG thick film was epitaxially grown on a Y 3 Al 5 O 12 single crystal substrate with in-plane orientation relationship. Under UV light and α-ray irradiations, the Ce3+:GAG film exhibited a broad emission centered at 560 nm corresponding to the 5d–4f transition of Ce3+ ions. The scintillation light yield of the Ce3+:GAG film was 14250 photons per 5.5 MeV with a fast decay constant of 82.8 ns for the α-ray irradiation from the 241Am source. • Ce3+:GAG thick film phosphor was epitaxially grown using CVD method. • Ce3+: GAG exhibited photoluminescence at 560 nm due to Ce3+ 5d-4f transition. • Scintillation light yield was 14250 photons per 5.5 MeV, comparable to Ce3+:YAG. [ABSTRACT FROM AUTHOR]

Lead halide perovskites are reportedly a very promising group of materials for scintillation due to their fast sub-nanosecond exciton luminescence, small band-gaps, and high theoretical light yield. Unfortunately, they only show emission at cryogenic temperatures. In this work single crystals of CsPbBr 3 and CsPbCl 3 are studied at cryogenic temperatures. Upon comparing the 10 K emission spectra measured under X-ray and UV–vis excitation, a new near-infrared emission was found for both CsPbBr 3 and CsPbCl 3 only present under X-ray excitation. The integral light yields of CsPbBr 3 and CsPbCl 3 at 10 K are estimated to be 34,000 and 2,200 photons/MeV under 40 keV X-ray excitation, respectively. The main components of the light yield of CsPbBr 3 at 10 K are the near band-gap free exciton emission that suffers from self-absorption and the broad near-infrared emission that falls outside the typical detection range of a photo-multiplier tube. Due to the combination of the two aforementioned effects it was not possible to measure a γ -ray pulse height spectrum for CsPbBr 3 at 10 K. Despite all the suitable properties, like the fast decay, a small band-gap, and the positive prospects of 3D perovskite based scintillators, we conclude that these materials perform poorly as scintillation crystals. [ABSTRACT FROM AUTHOR]

0.5, 1, 2, and 5% Er-doped La 3 Ga 5 SiO 14 (LGS) single crystals were synthesized by the Floating Zone method and the photoluminescence (PL) and scintillation properties were characterized. Emission peaks appeared at visible–near-infrared (NIR) regions. Their spectral features matched with those due to the 4f–4f transitions of Er3+. The PL quantum yields of 0.5, 1, 2, and 5% Er-doped samples were respectively 45.0, 73.3, 82.5, and 69.4%. The decay times due to the 2H 9/2 –4I 15/2 transitions of Er3+ were obtained when visible ranges were monitored under excitation of both visible lights and X-rays. All the prepared samples showed good linearity between the X-ray exposure dose rate and scintillation signals in NIR ranges. The best lower detection limit in prepared samples was 5 mGy/h recorded by the 2% Er-doped LGS. • Er-doped La 3 Ga 5 SiO 14 single crystals were synthesized by the Floating zone method. • Luminescence due to 4f–4f transitions of Er3+ was observed in both visible and near-infrared regions. • Quantum yields of 0.5, 1, 2, and 5% Er-doped samples were respectively 45.0, 73.7, 82.5, and 69.4%. • The best lower detection limit in prepared samples was 5 mGy/h obtained by 2% Er-doped sample. [ABSTRACT FROM AUTHOR]

In the present article, the influence of the activator concentration and impurity content of raw materials on the luminescence and scintillation properties of Li2CaSiO4 was studied. Polycrystalline powder material was obtained by the sol–gel method. It was shown that europium had limited solubility in the host lattice with a limiting concentration proximate to 0.014 formula units. The maximum intensity of photoluminescence was observed with a divalent europium concentration of 0.002 formula units; the light yield under alpha-particle excitation was measured to be 21,600 photons/MeV for ~200 μm of coating, and under neutron excitation, it was calculated to be 103,800 photons/n, the scintillation kinetics was characterized by an effective decay time of 157 ns. These properties and the transparency in the visible spectrum make it possible to produce scintillation screens with a coating of Li2CaSiO4 for detecting neutrons, alpha particles and low-energy beta radiation. The low Zeff (~15) of this compound makes it less sensitive to gamma rays. The 480 nm blue emission peak makes this material compatible with most commercial PMT photocathodes, CCD cameras and silicon photomultipliers, which have a maximum quantum efficiency in the blue–green spectral region. [ABSTRACT FROM AUTHOR]

The ability of a scintillator to absorb and convert the high-energy X-ray photons to low-energy visible photons is crucial for the application of X-ray in medical tests, security checks and scientific research. However, traditional scintillation crystals are synthesized by complex preparation process with high cost, hindering the wide development in practical applications. Here, Tb3+ doped sodium silicate glass, which exhibits remarkable scintillation property and recoverability to X-ray irradiation, was successfully prepared by an exercisable melt-quenching method. The obtained scintillator shows intense radioluminescence, which is about 1.5 times higher than that of the reference of Bi 4 Ge 3 O 12. The damaged glass to X-ray irradiation can be returned to the original state after heat treatment again, indicating excellent recovery. Moreover, the scintillator displays wonderful thermal stability with the fluorescence intensity at 573 K still remaining 96% at room temperature. These results demonstrate that the obtained scintillating glass has potential application towards the real world. [ABSTRACT FROM AUTHOR]

A special group of luminescence materials are scintillators for thermal neutron detection. Due to the properties of neutrons (contrary to e.g. electrons or gamma photons), a different approach has to be utilized—the high content of atoms with the sufficient absorption cross‐section toward neutrons and lower material density are needed. This work pursues a basic study of LiSrBO3 and LiSr4(BO3)3 doped with cerium or europium—materials promising as thermal neutron scintillators. These borates exhibit promising properties such as the high content of lithium and boron, suitable density, and proper environment for luminescent ions. Radioluminescence of these ceramic borates doped with cerium and europium was examined and promising samples were further characterized by photoluminescence spectroscopy and radioluminescence and photoluminescence kinetics measurement. The radioluminescence study of these borates is published for the first time. Cerium‐doped borates, in particular, exhibit a very promising response to an X‐ray excitation. [ABSTRACT FROM AUTHOR]

The photoluminescence and scintillation properties of n-bromophenethylammonium lead chloride ((n-BrPEA) 2 PbCl 4) (n = 4, 3, and 2) and phenethylammonium lead chloride ((PEA) 2 PbCl 4) have been investigated. All the samples showed broad emission peaks at 400–700 nm upon excitation by UV light or X-ray. The decay time constants of 8–28 ns were obtained which originated from the recombination of self-trapped exciton (STE) within inorganic layers. The afterglow levels at 20 ms after 2 ms of X-ray irradiation of (4-BrPEA) 2 PbCl 4 and (3-BrPEA) 2 PbCl 4 (76 and 55 ppm) were better than (PEA) 2 PbCl 4 (379 ppm). The light yield of (4-BrPEA) 2 PbCl 4 (3100 photons/5.5 MeV-α) was higher than (PEA) 2 PbCl 4 (1400 photons/5.5 MeV-α). • (BrC 6 H 4 C 2 H 4 NH 3) 2 PbCl 4 crystals were grown by the slow cooling method. • All the crystals showed the luminescence due to the recombination of the self-trapped excitons confined in inorganic layers. • The (4-BrC 6 H 4 C 2 H 4 NH 3) 2 PbCl 4 crystal showed the highest QY in the present crystals. • The light yields of the (4-BrC 6 H 4 C 2 H 4 NH 3) 2 PbCl 4 crystals surpassed that of the unsubstituted crystal. [ABSTRACT FROM AUTHOR]

This study provided the first in-depth investigation of the effects of large dopant incompatibility (Pr3+ and La3+ ions) on the small host lattice element (Lu3+) in Lu 3 Al 5 O 12 (LuAG) single crystal. The growth of such complex crystals from the melt presented many challenges. By engineering the ionic radius ratio of RE- and M-site cations, a single-crystal phase stabilized by configurational entropy was achieved. This investigation elucidated the crystallization behavior of configurationally disordered rare-earth aluminum garnet oxide (Lu 1−x−y Pr x La y) 3 Al 5 O 12 from the melt and characterized its functional properties, including microstructural, optical, photoluminescence, and scintillation properties, between 5 and 300 K. Relaxation of the imposed strain energy led to local perturbations and destabilization of the garnet structure. Multielemental EDS mapping, micro-Raman spectroscopy, and thermoluminescence revealed the mechanism by which atomic size mismatch drove a smooth transition from the garnet to the perovskite phase in high entropy garnets. The optical, photoluminescence, and scintillation measurements provided fundamental insights into property changes driven by incompatibility doping. Standard and modified Judd-Ofelt theory analysis of absorption spectra determined the phenomenological Judd-Ofelt parameters Ω λ and radiative lifetimes. Atomic size mismatch engineering offers a promising approach to overcoming the limitations of conventional eutectic synthesis methods. • Perovskite inclusions, driven by atomic size mismatch, extend from rim to core. • Controlled incompatible La3+,Pr3+ codoping in LuAG modify functional properties. • Scintillation light yield improved up to 30% in La3+ codoped LuAG:Pr crystals. • (La,Pr)AlO 3 perovskite forms due to size mismatch of La3+ and Pr3+ with Lu3+. • Lattice disorder affects the intensity ratio of Pr³⁺ 5d→4 f and 4 f→4 f emissions. [ABSTRACT FROM AUTHOR]

• CuI thin films have been synthesized in iodine solution at room temperature. • An apparent NBE peak can be recognized both in PL and XEL spectra. • Iodine-rich condition is beneficial to improve the XEL yield of CuI thin films. CuI is considered as a potential candidate for fast scintillator material due to the fast decay time. However, the ever-reported CuI scintillator usually demonstrates a more intensive deep-level emission with the decay time as long as 2.82 μs, which is unfavorable for the application as a fast scintillator material. In present work, γ-phase CuI were synthesized by iodizing Cu thin films in iodine solution at room temperature. An apparent near band-edge emission (NBE) is observed both in photoluminescence and X-ray excited luminescence spectra. By analyzing the variation of the relative intensity ratio of the sub-peaks composing NBE against different fabrication conditions, it can be deduced that Cu vacancy and surface chemisorbed iodine are responsible for the above luminescence behavior. It is hoped that these findings may boost the exploration of CuI thin films as fast scintillator materials. [ABSTRACT FROM AUTHOR]

(n-ClC 6 H 4 C 2 H 4 NH 3) 2 PbCl 4 ((n-ClPEA) 2 PbCl 4) (n = 2, 3, and 4) and (n-C 6 H 5 C 2 H 4 NH 3) 2 PbCl 4 ((PEA) 2 PbCl 4) crystals were synthesized by the slow-cooling method, and the photoluminescence (PL) and scintillation properties were evaluated. All the samples showed self-trapped excitons luminescence at 400–700 nm. The PL quantum yields of the (n-ClPEA) 2 PbCl 4 (n = 2, 3, and 4) and (PEA) 2 PbCl 4 crystals were 2.2, 0.9, 11.2, and 2.2 %, respectively. In the pulse-height spectra of 241Am α-rays (5.5 MeV), full energy absorption peaks were observed, and the light yields of (n-ClPEA) 2 PbCl 4 (n = 2, 3, and 4) and (PEA) 2 PbCl 4 crystals were respectively calculated to be 530, 490, 2,800, and 1,400 photons/5.5 MeV-α with typical errors of ± 10 %. [ABSTRACT FROM AUTHOR]

We have investigated the scintillation properties of Ce-doped Li2O-ZnO-P2O5 glasses. The samples were prepared using a conventional melt-quenching method with low heating temperatures from 900 to 950 °C. All the samples showed halo patterns in their X-ray diffraction (XRD) patterns. In the X-ray-induced scintillation spectra, each sample showed a single emission peak that can be ascribed to luminescence due to the 5d-4f transitions of Ce3+ ions. In the pulse height spectra of the samples, thermal neutron detection peaks were observed. Their light yields were estimated to be approximately 90-180 photons/neutron. Although the Cedoped Li2O-ZnO-P2O5 glasses show low light yields, they can be regarded as thermal neutron scintillators that can be produced with low heating temperatures. [ABSTRACT FROM AUTHOR]

• CeF 3 -doped CaF 2 transparent ceramics were fabricated by spark plasma sintering. • The transparent ceramics showed luminescence due to the 5d→4f transitions of Ce3+. • A direct correlation between scintillation light yields and TSL/OSL intensities was demonstrated. We report on the luminescence properties of CaF 2 transparent ceramics having various concentrations of CeF 3 (0.1 %, 0.5 %, and 1 %). Scintillation emissions centered at approximately 318, 345, and 386 nm derived from the 5d→4f transition of Ce3+ were detected, and scintillation light yields were determined to be 8600 photons/MeV (0.1 % CeF 3), 1930 photons/MeV (0.5 % CeF 3), and 1850 photons/MeV (1 % CeF 3) under gamma-ray irradiation from 241Am. The Ce-doped CaF 2 transparent ceramics showed thermally stimulated luminescence (TSL) with a broad glow peak at around 115–145 °C, and their dose response curves were determined over a broad dose range (0.01–3 mGy). Moreover, optically stimulated luminescence (OSL) exponential decay curves were obtained under 500 nm stimulation light, and dose response curves were obtained in the dose range of 0.1–100 mGy. The minimum detectable dose was estimated to be 0.1 mGy. A direct correlation between scintillation light yields under gamma-ray irradiation and TSL/OSL intensities was demonstrated. [Display omitted] [ABSTRACT FROM AUTHOR]

(C 4 H 9 NH 3) 2 PbI 4 and (C 6 H 5 C 4 H 8 NH 3) 2 PbI 4 single crystals were synthesized by the slow cooling method, and their optical and scintillation properties were evaluated. Both samples had sharp X-ray diffraction peaks with intervals of (0 0 2 l) (l = 5–7). Absorption edges of (C 4 H 9 NH 3) 2 PbI 4 and (C 6 H 5 C 4 H 8 NH 3) 2 PbI 4 were confirmed at 535 and 520 nm, respectively. They showed luminescence due to the recombination of excitons at 500–700 nm. Scintillation decay times at 0.5–0.7 ns were obtained by approximation of decay curves. The light yields of (C 4 H 9 NH 3) 2 PbI 4 and (C 6 H 5 C 4 H 8 NH 3) 2 PbI 4 were respectively evaluated to be 1200 and 1500 photons/5.5 MeV-α by measuring full absorption peaks of 241Am α-rays. • (C 4 H 9 NH 3) 2 PbI 4 and (C 6 H 5 C 4 H 8 NH 3) 2 PbI 4 single crystals were grown by the slow cooling method. • Luminescence due to the recombination of free excitons was observed. • Scintillation decay times of sub-nanoseconds were observed. • Light yield of (C 6 H 5 C 4 H 8 NH 3) 2 PbI 4 was 1500 photons/5.5 MeV-α. [ABSTRACT FROM AUTHOR]

(C 6 H 5 C 2 H 4 NH 3) 2 Pb 1- x Ca x Br 4 (x = 0.05, 0.1, and 0.25) crystals were grown by the solvent diffusion method and evaluated for the photoluminescence and scintillation properties. When irradiated by X-rays, emission peaking at 440 nm due to exciton emission was observed. The pulse height spectra of (C 6 H 5 C 2 H 4 NH 3) 2 Pb 1- x Ca x Br 4 under 137Cs γ-ray irradiation demonstrate that the light yields were 20,000, 17,000, and 16,000 ph/MeV in x = 0.05, 0.1, and 0.25 samples, respectively. Ca-substitution significantly enhances the photoluminescence quantum yield and scintillation light yield. • (C 6 H 5 C 2 H 4 NH 3) 2 (Pb,Ca)Br 4 crystals were evaluated for the photoluminescence and scintillation properties. • (C 6 H 5 C 2 H 4 NH 3) 2 (Pb,Ca)Br 4 crystals exhibit a sharp emission peaking at 440 nm due to exciton luminescence. • Pulse height spectra under 137Cs γ-rays demonstrate the light yields was 20,000 ph/MeV. • Ca-substitution enhances both the photoluminescence and scintillation properties. [ABSTRACT FROM AUTHOR]

The low-energy ultraviolet or visible photons can be produced by the interaction between the scintillator materials and ionizing radiation. For this reason, scintillator materials are widely used as radiation detectors, which are prevalently utilized in different applications such as nuclear medicine imaging, homeland security, high-energy physics, oil drilling explorations, etc. Herein, a high-atomic-number (Z) zirconium-based metal-organic framework nanoflower material CJLU-1 (Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 (OH) 6 (TCA) 2 (H 2 O) 6) (H 3 TCA = tri-carboxylic acids 4,4′,4″-nitrilotribenzoic acid) was synthesized and can effectively convert X-ray into visible light. CJLU-1 is composed of secondary structural unit hexagonal Zr metal cluster and connected by TCA ligands. The photo luminescence spectra (PL) emission peak and excitation peak of CJLU-1 are at 470 nm and 395 nm respectively. CJLU-1 exhibited radioluminescence (RL) peak with a maximum at 480 nm under steady-state excitation with X-rays. Moreover, by accommodating different guest molecules such as xylene and RhB in the same MOF material, intensity-tunable X-ray scintillation can be facilely achieved, providing a new class of scintillating materials with luminescence intensity tunability. The high-Z hexagonal Zr clusters, which are arranged in an orderly fashion, absorb and interact with the ionizing radiation and sensitize the adjacent organic ligands TCA to produce efficient RL. This work contributes to the development of high-Z zirconium-based MOFs and RL intensity-tunable scintillation materials towards future practical nuclear sensing applications. A high-atomic-number (Z) zirconium-based metal-organic framework nanoflower material CJLU-1 was synthesized and can effectively convert X-ray into visible light. [Display omitted] • A zirconium-based MOF was constructed and realized tunable radioluminescence upon accommodation of guest molecules. [ABSTRACT FROM AUTHOR]

(K,Rb) 2 CuBr 3 crystals were fabricated by the slow cooling method, and their photoluminescence (PL) and scintillation properties were examined. Emission bands were observed at 350–550 nm under UV and X-ray irradiation. PL quantum yields of K 2 CuBr 3 , (K 0.25 ,Rb 0.75) 2 CuBr 3 , (K 0.5 ,Rb 0.5) 2 CuBr 3 , (K 0.75 ,Rb 0.25) 2 CuBr 3 , and Rb 2 CuBr 3 were respectively 75.8, 71.0, 82.3, 96.9, and 96.3%. The scintillation decay curves were approximated by a sum of three exponential functions, and the decay time constants due to recombination of self-trapped excitons were 58–63 μs. The afterglow levels of the K and Rb-mixed samples at 20 ms passed after X-ray irradiation decreased to 10–40 ppm, compared with those of K 2 CuBr 3 and Rb 2 CuBr 3. Among these samples, (K 0.75 , Rb 0.25) 2 CuBr 3 showed the highest light yield of 7400 ph/MeV among the samples calculated from the pulse height spectra of 137Cs γ-rays (662 keV). • (K,Rb) 2 CuBr 3 crystals were synthesized by the slow cooling method. • The afterglow levels of the (K,Rb) 2 CuBr 3 were 10–40 ppm. • (K 0.75 ,Rb 0.25) 2 CuBr 3 showed the highest light yield (7400 ph/MeV) in prepared samples. [ABSTRACT FROM AUTHOR]

The near-band luminescence of doped ZnO is promising for advanced scintillators; however, the dopant type and concentration effects require a detailed study. Undoped and Ga-doped ZnO nanopowders were prepared by a microwave-assisted solvothermal method and the gallium concentration effect on luminescence properties was studied. The near-band luminescence peak position dependence on gallium concentration was observed. Near-band luminescence intensity versus defect luminescence intensity ratio was explored for different gallium concentrations and the optimal value was determined. Samples were prepared with dopant concentrations between 0.2 and 1.5 at%, XRD analysis confirmed that samples contained only zinc oxide hexagonal wurtzite phase. The results of the research showed that ZnO:Ga containing 0.9 at.% gallium was promising for scintillators. [ABSTRACT FROM AUTHOR]

In this study, we fabricated Cs 3 ScCl 6 crystals doped with different concentrations of Ce and investigated their luminescence properties. In both the photoluminescence (PL) and scintillation spectra, emission bands attributable to Ce3+ 5d–4f transition were observed. The PL temporal profiles revealed decay time constants of ~35 ns, which are typical values for Ce3+ 5d–4f transition. In the scintillation temporal profiles, two decay components were observed. The fast and slow components could be attributed to Ce3+ 5d–4f luminescence and self-trapped excitons (STEs) or a slow energy transfer from STEs to Ce3+, respectively. The maximum light yield was 9200 photons/MeV for a Ce concentration of 0.5 mol%. [ABSTRACT FROM AUTHOR]

The lead tungstate crystal (PbWO4, PWO) is one of the widely used scintillation materials for electromagnetic calorimeters (EMCs) in high-energy physics experiments. The degradation of the optical transmittance in the range of the luminescence spectrum under ionizing radiation leads to losses of the light output resulting in the deterioration of the energy resolution and limiting the lifetime of the calorimeter. A possible way to restore radiation damage is the in situ illumination by visible or near-infrared light of the whole crystal volume. It allows recovering the transmittance losses due to the depopulation of the color centers. Such a kind of stimulated recovery subsystem based on a blue light-emitting diode is considered for the EMC of the PANDA detector at Facility for Antiproton and Ion Research (FAIR) (Darmstadt, Germany). Here, we report on the stimulated recovery studies of the lead tungstate radiation damage induced by external light from laser diodes at different wavelengths. The level of technological development of laser diodes allows increasing the efficiency of the stimulated recovery. [ABSTRACT FROM AUTHOR]

The urgent demand for radiation detection in diverse applications boosts extensive investigations on scintillators. However, the current scintillating materials are mostly limited to mono-crystals with high cost, restricted volume and time-consuming fabrication techniques. Here, we report an efficient and transparent Tb3+-doped Sr 2 GdF 7 glass ceramic (GC) prepared via simple melt-quenching method, and its optical response to X-ray. By incorporating Tb3+ into crystallized Sr 2 GdF 7 inside a typical aluminosilicate glasses, highly enhanced green emission was observed under UV and X-ray excitation. After thermal treatment, the internal and external photo-luminescence quantum yields can be as high as 59.1 and 26.4%, respectively, with the high transparency (65%@550 nm) preserved. More interestingly, this composite material, combining the advantages of oxide glasses and fluoride crystals, presents strong X-ray excited luminescence (XEL). Its XEL intensity is 194% of that of commercial BGO scintillator. Evidenced by detailed optical and structural properties, it can be concluded that rare earth ions activated bulk oxyfluoride glass ceramics with unique merits, such as low-cost, high efficiency and intense radio-luminescence, could be alternative scintillating materials for high energy ray detection. [ABSTRACT FROM AUTHOR]

This study concerns cerium and boron doped Lu 3 Al 4 Sc 1 O 12 and Gd 3 Al 3 Sc 2 O 12 garnet µ-crystalline powders, which were synthesized for the first time. Rare earth ion, particularly Ce3+ activated garnets, due to their high density and efficient Ce3+ luminescence upon blue, UV, or x-ray excitation, can be used as scintillators that convert high-energy radiation into visible light. The incorporation of B3+ and Sc3+ ions into the garnet matrix corresponds to the improvement of the scintillating properties. Boron in these compounds could act like a flux and thus modulate particle morphology, while scandium solely changes the physical and luminescent properties of these garnets. From the measured radioluminescence emission spectra, it could be concluded that boron doping results in a higher emission intensity when the compounds are excited by high-energy radiation. The most striking effect is that the decay time is reduced, and the quantum efficiency of the compounds increases. After improving the kinetic properties of these compounds, it is possible to discuss a wider application of the synthesized materials. In addition to the aforementioned properties, room temperature as well as temperature dependent photoluminescence emission, excitation, and decay times at different temperatures were taken for all samples. The elemental composition of the samples was determined by using the ICP-OES technique. The crystal structure was analyzed by means of powder XRD. Particle morphology and size distribution were also investigated. The main idea of this research is to synthesize new and adjusted garnet type compounds that show better luminescent properties, which are required for scintillator materials. • Pure B3+ and Sc3+ co-doped LuAG:Ce and GdAG:Ce were synthesized by Sol-Gel method. • Reflectance spectra indicated about good quality of synthesized compounds. • Boron doping led to an increase in radio/photo luminescence intensities. • A reduction in decay times was caused by B3+ and Sc3+ co-doping. • Co-doping with B3+ led to an increase in quantum efficiency. [ABSTRACT FROM AUTHOR]

BaCl 2 :Eu transparent ceramics were synthesized by the spark plasma sintering method, and concentration dependence of Eu on optical and scintillation properties was investigated. BaCl 2 :Eu transparent ceramics showed photoluminescence (PL) and scintillation peaks at 400 nm due to 5d–4f transition of Eu2+. The PL and scintillation decay time constants of BaCl 2 :Eu transparent ceramics were ∼400 ns. The PL quantum yields (QY s) of 0.05, 0.1, 0.5, and 1% BaCl 2 :Eu transparent ceramics were 28.5, 25.6, 16.2, and 13.9%, respectively. The afterglow levels of BaCl 2 :Eu transparent ceramics were lower than CsI:Tl single crystal in practical use. The scintillation light yield of the 0.5% doped BaCl 2 :Eu transparent ceramic was 9800 photons/MeV when γ-rays by 137Cs were irradiated. • BaCl 2 :Eu transparent ceramics were synthesized using the SPS method. • We investigated the optical and scintillation properties. • The scintillation peak due to 5d–4f transition of Eu2+ was observed at 400 nm. • The 0.5% Eu-doped sample showed the highest LY (9800 ph/MeV) under 137Cs γ-ray irradiation. [ABSTRACT FROM AUTHOR]

The study of plastic scintillators with polyurethane (PU) matrix based on cycloaliphatic isocyanate 4,4′-methylenebis (cyclohexyl isocyanate) (H 12 MDI) and 2,5-diphenyloxazole (PPO) as a luminescence activator is presented. A number of samples with different PPO content amounting up to 20 wt% were synthesized and their optical and luminescence characteristics were investigated. Pure H 12 MDI – PU based polymer exhibits low optical density in the spectral region 350–500 nm characteristic of the PPO emission band. The PU sample loaded with 5 wt% PPO demonstrated a light yield of 1088 photons/MeV and ultrafast rise and decay time of few picoseconds and few nanoseconds, respectively. The estimated coincidence time resolution (CTR) value for a PU sample is 1.4 times smaller than that known for a commercial scintillator BC-422 available for ultrafast timing applications. • A new plastic polyurethane (PU) based scintillator has been synthesized. • The concentration of PPO dopant in the PU scintillator can reach up to 20 wt%. • The PU sample loaded with 5 wt% PPO has a light yield of 1088 photons/MeV. • The new PU scintillator has an ultrafast rise time. • The CTR of the new PU scintillator is 1.4 times smaller than that of BC-422. [ABSTRACT FROM AUTHOR]

Scintillation and luminescence properties of a novel organic crystal scintillator, 1,4-bis(2-methylstyryl) benzene (bis-MSB), were measured and compared with those of the conventional trans-stilbene organic crystal scintillator. Although trans-stilbene has been used for beta or neutron detection, trans-stilbene cannot be applied at high temperature conditions due to a lower melting point (124 °C). Liquid scintillators or plastic scintillators also cannot be used at high temperature. Usually, bis-MSB has been used as dopant in liquid scintillators to obtain fast scintillation decay and high luminescence quantum yield, and its melting point is 181 °C higher than that of trans-stilbene. In this paper, we focused on bis-MSB in solid state. The bis-MSB and trans-stilbene crystals were grown by the self-seeding vertical Bridgman method using double quartz ampoules. The bis-MSB crystal had the fast decay time of ∼4.2 ns and the increased light yield of ∼12,000 ph/5.5 MeV(α), while trans-stilbene had the decay time of ∼8.5 ns and the light yield of ∼8500 ph/5.5 MeV(α). The photoluminescence quantum yield was almost constant up to 125 °C for bis-MSB and only up to 50 °C for trans-stilbene. We succeeded in obtaining the novel organic crystal scintillator which can operate even at higher temperature up to 125 °C. • The scintillation properties of the bis-MSB crystal were investigated. • Transparent crystals were grown by self-seeding vertical Bridgman method. • Bis-MSB had better scintillation properties compared to trans-stilbene. • The temperature dependence of luminescence quantum yield of bis-MSB was studied. [ABSTRACT FROM AUTHOR]

Pr:Li 6 Y(BO 3) 3 and Pr,Ce:Li 6 Y(BO 3) 3 crystals were grown by the Czochralski method. The luminescence properties of the Pr:Li 6 Y(BO 3) 3 and Pr,Ce:Li 6 Y(BO 3) 3 crystals, such as their optical transmission, photoluminescence and X-ray induced luminescence spectra were investigated. The scintillation properties of the multi-channel energy spectrum of the Pr,Ce:Li 6 Y(BO 3) 3 crystal under thermal neutrons and gamma-ray excitation were also studied. The energy resolutions of the Pr,Ce:Li 6 Y(BO 3) 3 crystal, which had a size of 8 × 7 × 2 mm3 , excited by moderated 252Cf for the 10B (n,α)7Li and 6Li (n,α)3H reactions were determined to be 42% and 16%, respectively. The decay time under 320 nm UV light excitation was fitted to be 27 ns. Therefore the Pr,Ce:Li 6 Y(BO 3) 3 crystal is a promising fast scintillator for thermal neutron detection with good energy resolution, fast decay time and possible pulse-height discrimination ability. • Pr3+, Ce3+ co-doped Li 6 Y(BO 3) 3 crystals were grown using Czochralski method. • The energy resolution of Pr,Ce:LYBO crystal for 10B (n,α)7Li reaction is 42%. • The energy resolution of Pr,Ce:LYBO crystal for 6Li (n,α)3H reaction is 16%. • The photoluminescence decay time of Pr,Ce:Li 6 Y(BO 3) 3 crystal is 27 ns. [ABSTRACT FROM AUTHOR]

Eu-doped CaAl2O4 bulk crystals were synthesized by the floating zone (FZ) method, and their photoluminescence (PL) and scintillation properties were investigated firstly in a bulk crystal. The crystal samples exhibit PL and radioluminescence (RL) with a broad emission peaking around 440 nm as well as sharp peaks appearing around 600 nm, which are similarly observed for powder samples. Suggested from the decay time constants, they are attributed to the 5d-4f transitions of Eu2+ and the 4f-4f transitions of Eu3+, respectively. From the pulse height spectrum under 241Am γ-ray (59.5 keV) exposure, the light yield (LY) of a 3.0% Eu:CaAl2O4 bulk crystal is approximately 12000 ph/MeV. [ABSTRACT FROM AUTHOR]

Abstract In this study, the Gd3+-substituted yttrium aluminum perovskite epitaxial films activated by Ce3+ ions, (YGd)AlO 3 :Ce3+ with Gd content 0–44%, were prepared by liquid phase epitaxy technique and their optical, luminescence, and scintillation properties were studied. The results showed that films with Gd content below 20% had greater photoluminescence and radioluminescence intensities. For higher Gd concentrations, the Ce3+ emission gradually decreased and the Ce3+ decays were accelerated. The model of bidirectional non-radiative energy transfer between Gd3+ and Ce3+ ions and energy migration over the Gd3+ sublattice is suggested and the processes responsible for the observed effects are discussed. Highlights • (GdY)AlO 3 :Ce3+ perovskite scintillators were characterized. • Bidirectional Gd3+-Ce3+ energy transfer in GdYAP:Ce perovskite was proposed. • Gd co-doped YAlO 3 :Ce3+,Gd3+ perovskite films were prepared by liquid phase epitaxy. [ABSTRACT FROM AUTHOR]

Abstract LaAlO 3 perovskite single crystals doped with Ce, Eu or Tb have been grown by micro-pulling-down method. X-ray diffraction analysis confirmed low-temperature rhombohedric phase. Energy-dispersive Laue mapping revealed sub-grains in the grown crystals. For the Ce-doped crystals, very low radioluminescence efficiency was found and the observed emission was ascribed to defects. Photoluminescence spectra were significantly different from the radioluminescence ones. They were significantly quenched at room temperature and the related luminescence showed also unusually high Stokes shift. High radioluminescence efficiency was found for the Tb-doped samples and especially for the Eu-doped ones, which would point to the fact that in LaAlO 3 the scintillation process is more favorable for the luminescence ions which tend to capture an electron first. Highlights • Morphology of the grown rare-earth-doped LaAlO3 crystals was studied. • Role of the growth atmosphere explained by its influence on Ce valence state. • Origin of radioluminescence explained by defect emission in Ce-doped crystals. • High radioluminescence efficiency found for Eu-doped crystals. [ABSTRACT FROM AUTHOR]

Abstract We have investigated scintillation and thermoluminescence properties of the 20SrO-20BaO-40Nb 2 O 5 -20P 2 O 5 (SBNP) glass and glass-ceramics containing Sr 0.5 Ba 0.5 Nb 2 O 6 crystallites. The SBNP glasses were prepared by a conventional melt-quenching method. The obtained glasses were annealed at various temperatures and holding times for nucleation and growth of nanocrystallites. X-ray diffraction patterns revealed that samples were either glass or glass-ceramic containing Sr 0.5 Ba 0.5 Nb 2 O 6 nanocrystallites, and heat treatments at higher temperatures and longer holding times have promoted the crystallization. Furthermore, radioluminescence and TL intensities were higher for the glass-ceramics than glass; thus, efficient luminescence can be yielded in glass-ceramics. [ABSTRACT FROM AUTHOR]

Microstructural and luminescent properties of lithium lanthanum phosphate LiLaP 4 O 12 (LiLaPO), undoped and doped with trivalent rare earth (RE 3+ , RE = Ce, Eu, and Tb) ions, were studied. LiLaPO powders were synthesized by sol-gel method assisted by polyvinyl alcohol (PVA). The structural phase analysis was confirmed by X-ray powder diffraction (XRD). Scintillator properties were investigated to evaluate the luminescent response of the material under excitation with X-rays. The scintillation efficiency of the doped samples were compared to the one measured for a known BGO scintillator and it was shown that Tb-doped LiLaPO showed efficiency 30% higher than the BGO one. The chromaticity diagram was obtained from radioluminescent (RL) measurements. The stability of the RL response was investigated during long term X-ray exposure. The results showed that the RL efficiency of the LiLaPO increased almost by 40%, for the Ce-doped sample, and almost 25%, for Eu and Tb-doped samples, as the exposure time increased. This behavior was attributed to the presence of the deep trapping centers that trap charge carriers during the first stage of the irradiation, with a subsequent release of the trapped charges increasing the probability of the electron-hole pair recombination as a function of the time. Time-resolved RL was carried out to investigate the luminescent decay time for doped samples and, for Ce-doped samples, a fast decay component with luminescent decay time of 17 ns dominates. Typical millisecond decay components with decay time constants of 3.12 ms and 5.17 ms were observed for Tb 3+ and Eu 3+ -doped LiLaPO, respectively. Additionally, a slow component with decay time constant of 31.3 ms was also found for Eu 3+ -doped LiLaPO and this component was attributed to the existence very shallow traps in the material. [ABSTRACT FROM AUTHOR]

This paper reports the effects of Au codoping on the scintillation and optical properties of BaBrCl:Eu single crystals grown by the Bridgman-Stockbarger method. The study, performed by varying both Eu and Au concentrations, demonstrates the highly effective role of Au codoping for improving the scintillation light output for all the considered europium concentrations. These, up to trifold, improvements are accompanied by a substantial reduction in the long scintillation decay tails, and in the thermo- and optically stimulated luminescence intensities with respect to crystals doped only with Eu. The role of Au ions is discussed based on these experimental results. [ABSTRACT FROM AUTHOR]

Abstract We report the synthesis and luminescence properties of new layered mixed-anion compounds, Sr 2 ScCuSeO 3 and Sr 3 Sc 2 Cu 2 Se 2 O 5. Sr 2 ScCuSeO 3 and Sr 3 Sc 2 Cu 2 Se 2 O 5 were synthesized by solid-state reaction and were investigated using x-ray diffraction, diffuse reflectance, and photoluminescence spectroscopies. Both compounds have very similar properties except for their optical band gaps and emission peak energies. At room temperature, Sr 2 ScCuSeO 3 and Sr 3 Sc 2 Cu 2 Se 2 O 5 exhibit optical band gaps energies of 2.9–3.0 eV. The excitonic luminescence with very fast emissions of ∼30 ps were observed in both compounds even at room temperature. This feature of the compounds makes them suitable for fast scintillator applications. Our results suggest that the luminescence properties such as emission peak energies and lifetimes of these layered mixed-anion compounds can be controlled by changing their structure and composition. Highlights • New layered mixed-anion compounds were successfully synthesized by solid-state reaction. • Sr 2 ScCuSeO 3 and Sr 3 Sc 2 Cu 2 Se 2 O 5 exhibit band gap energies of 2.9–3.0 eV, respectively. • Under UV excitation, Sr 2 ScCuSeO 3 and Sr 3 Sc 2 Cu 2 Se 2 O 5 exhibit a fast decay times around 30 ps even at room temperature. • Except for the emission decay, the observed optical properties are almost similar to other chalcogenide oxides. • The luminescence properties of these materials can be controlled by their composition and structure. [ABSTRACT FROM AUTHOR]

Ce:Cs 2 LiYCl 6 (CLYC) crystal is a marketable halide inorganic scintillator with very high light yield, excellent energy resolution and pulse-shape discrimination between gamma rays and thermal neutrons. Although the scintillation performance of Ce:Cs 2 LiLaCl 6 (CLLC) crystal is better than CLYC crystal, the promising application was restricted by the crystal growth difficulties. To utilize the advantage of La 3+ halide, research on the growth of Ce:Cs 2 LiLa x Y 1-x Cl 6 (0 < x ≤ 0.4) crystals were undertaken. The Ce:Cs 2 LiLa x Y 1-x Cl 6 with x = 0.05, 0.1, 0.2 and 0.4 were grown by the vertical Bridgman technique, and transparent Ce:Cs 2 LiLa 0.1 Y 0.9 Cl 6 samples were successfully obtained. The crystal structure and composition of the as-grown crystals were characterized by powder x-ray diffraction patterns. The luminescence and scintillation properties of the mixed elpasolites Ce:Cs 2 LiLa x Y 1-x Cl 6 (0 < x ≤ 0.4) crystals were also investigated. Finally, it was found that Ce:Cs 2 LiLa 0.1 Y 0.9 Cl 6 is a very promising gamma-rays and thermal neutrons scintillator with relatively high optical quality grown from vertical Bridgman method, acceptable energy resolution and relatively fast decay time. [ABSTRACT FROM AUTHOR]

TlSr 2 I 5 : Eu 2+ is a newly discovered scintillator that show promising scintillation properties for X- and γ-ray spectroscopy applications. Two zone vertical Bridgman technique is used for the growth of this scintillator. Luminescence properties of the grown crystals are measured under X-ray excitation at room temperature. Pure and Eu 2+ doped crystals contained broad emission bands between 445 and 670 nm peaking at 528 nm and 430–600 nm peaking at 463 nm, respectively. Energy resolution, light yield and decay time profiles are studied under 662 keV γ-ray excitation using 137 Cs radioactive source. Energy resolution of 4.2% (FWHM) is obtained for 3 mol% Eu 2+ doped crystal. For the same sample, light yield of 70,000 ph/MeV is also obtained. Three and two decay constants are observed for the pure and Eu 2+ doped samples, respectively at room temperature. Effective Z-number and density are found to be 61 and 5.30 g/cm 3 , respectively. [ABSTRACT FROM AUTHOR]

ZnSe1-xSx crystals with a higher content of selenium or sulfur ions adopt, respectively, a wurtzite or sphalerite structure. Luminescent properties of ZnSe1-xSx crystals are determined by ternary VZnZniOSe complexes for crystals with a cubic (sphalerite) lattice, and by sulfur vacancies VS for crystals with a hexagonal (wurtzite) lattice. Light output of ZnSe1-xSx crystals increases with increasing the sulfur content up to x = 0.3 and reaches the value of light output observed for 'classic scintillator' ZnSe(Te). At the same time, the ZnSe1-xSx bulk crystals possess better thermal stability at the same energy of emitted photons (hn ~ 2 eV) as compared to that of the ZnSe(Te) crystals. [ABSTRACT FROM AUTHOR]

The scintillation properties of Pr:CaF2 were studied in comparison with those of Eu:CaF2 under α-ray excitation using a sealed source of 241Am. The relative light yields of the Pr:CaF2 crystals were approximately 0.6-13% of the Eu:CaF2 crystal that is known as a conventional scintillator for charged-particle detection. The scintillation decay times of the Pr:CaF2 crystals were significantly faster than that of the Eu:CaF2 crystal. Therefore, the Pr:CaF2 crystals can be used for charged-particle measurements with high count rates. [ABSTRACT FROM AUTHOR]

Ce 3+ ions doped Li 6 Gd(BO 3 ) 3 crystal is a promising low density scintillators for thermal neutron detection. The Czochralski growth of LGBO crystal have been optimized and single crystals with larger sizes have been grown with different techniques. LGBO crystal bowl with diameter larger than 43 mm were grown with Iridium ring increasing the radial temperature gradient and after-heater decreasing the upside axial temperature gradient. Meanwhile LGBO crystal disk with diameter larger than 50 mm were also grown with very low pulling rate and radial temperature gradient. To investigate the overall performance of LGBO series of crystal, Li 6 Y(BO 3 ) 3 crystal and its mixed crystals with Li 6 Gd(BO 3 ) 3 have also been grown using Czochralski method. The thermal expansion coefficients of LGBO and LYBO crystals were investigated using the high temperature XRD patterns, respectively. The big difference between melting and freezing point meant that the metastable phases have formed during cooling cycle for the Ostwald's rule. The optical transmission spectra, x-ray stimulated, photoluminescence and thermal stimulated luminescence spectra were also investigated, respectively. And Li 6 Gd 0.1 Y 0.9 (BO 3 ) 3 :Ce crystal may be the most promising crystals for thermal neutron detection for the best light output by α particles and the highest light output ratio α/γof 0.16. [ABSTRACT FROM AUTHOR]

A transparent gadolinium-rich oxyhalide glass scintillator was developed for gamma ray spectroscopy with an energy resolution of 14.0% at 662 keV. To the best of our knowledge, this is the highest energy resolution reported for a glass-based scintillator. The high gadolinium content facilitated a scintillator density of 4.4 g/cm3. The high fluorine and bromine incorporation is advantageous for better uniformity and a good light output of ~3200 Ph/MeV. The peak emission at 431 nm with a FWHM of 90 nm, resulting from the fast Ce3+ transitions, yielded pulse-height spectra with distinctive peaks from 122 keV to 1.33 keV for gamma radiation from different nuclides. [ABSTRACT FROM AUTHOR]

(Pr x Y 0.9 La 0.1 ) 2 O 3 (x = 0.05, 1, 5) transparent ceramics were fabricated by conventional ceramic processing. The absorption, emission spectra excited by ultraviolet and X-ray as well as the excitation spectra have been investigated as a function of the Pr 3+ concentration. The emission under ultraviolet excitation shows the ability of Pr 3+ to downconvert ultraviolet light to blue emission. The strong excitation band at 430–520 nm is in good agreement with the emissions of InGaN blue chips (λ em = 450–470 nm), which can be efficiently excited by the 470 nm light and generate bright red emission at around 630 nm. The radioluminescence spectra demonstrate the possible application of Pr 3+ : (Y 0.9 La 0.1 ) 2 O 3 in scintillator. In addition, the concentration quenching observed in the case of the P1 and P5 ceramics leads us to conclude that an optimum Pr 3+ concentration to generate the best luminescence properties is achievable. Given overall luminescence properties, the low Pr 3+ content (0.5 mol%) doped (Y 0.9 La 0.1 ) 2 O 3 transparent ceramic is a potential candidate for the applications in the ultraviolet-based and InGaN blue chip based white light-emitting diodes, as well as the scintillators. [ABSTRACT FROM AUTHOR]

We have synthesized the Al 2 O 3 transparent ceramic by using spark plasma sintering (SPS) and investigated the dosimeter and scintillation properties for X-ray detections, in comparison with the single crystal. Under X-ray irradiation, emissions at 300, 400 and 693 nm were observed in both the samples. To identify the origins of these emissions, scintillation decay times were investigated. Based on the results, emissions at 300, 400 and 693 nm are attributed to F + centers, F centers and Cr 3+ impurity ions, respectively. The thermally-stimulated luminescence (TSL) glow curves of both the samples showed a main peak around 50 °C. In addition, glow peaks were observed at 190, 290 and 360 °C. The TSL spectra had broad emission bands in the 300, 400 and 693 nm, which approximately agreed with the scintillation spectra. The TSL response was confirmed to be linear to the irradiation dose for transparent ceramic over the dose range from 0.3 to 1000 mGy while the sensitivity of the single crystal was lower and the response range confirmed was from 30 to 1000 mGy. [ABSTRACT FROM AUTHOR]