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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]

The luminescent properties of the single crystals of Ce3+ doped (Gd 1−x−y Lu x Y y) 3 Al 5 O 12 :Ce (x = 0.1; y = 1.5) and Gd 3 Ga x Al 5-x O 12 :Ce (x = 2.7) garnets (GLYAG:Ce and GGAG:Ce) were investigated in this work. Both crystals were grown by the micropulling down method. The conventional absorption and luminescence spectral measurements together with the luminescent spectroscopy under excitation by synchrotron radiation were performed to characterize the optical properties of crystals. It has been found that cumulative effects of reducing the ion radius from Gd3+ to Y3+ and Lu3+ in the dodecahedral sites of the garnets host and alloying of Al3+ ions in octahedral positions instead Ga3+ ions increases the crystal field strength and causes the respective redshift of the Ce3+ emission spectra in GLYAG:Ce crystals in comparison with GAGG:Ce garnet. The energy transfer from Gd3+ cations to Ce3+ has also been registered at the emission spectra and excitation spectra of both crystals. The energies of creation of the excitons bound with the Ce3+ ions in GLYAG:Ce and GAGG:Ce hosts were found to be equal to 6.415 ± 0.15 eV and 6.22 ± 0.15 eV, respectively. Both crystals show well-distinguished thermo- and optically stimulated luminescence (TSL and IR OSL) after α - and β -particle irradiation. Meanwhile, GAGG:Ce crystals show significantly higher TSL and IR OSL intensities (by 3–4 times) and faster OSL decay kinetics in comparison with GLYAG:Ce counterpart. • Gd 1.4 Lu 0.1 Y 1.5 Al 5 O 12 :Ce (GLYAG:Ce) and Gd 3 Ga 2.3 Al 2.7 O 12 :Ce (GAGG:Ce) garnet crystals were grown using the micro-pulling down method. • Luminescent properties of crystals were investigated using conventional spectral methods and synchrotron radiation excitation. • The energy of creation of the excitons bound with the Ce3+ ions in GLYAG:Ce and GAGG:Ce hosts was found. • Gd 1.4 Lu 0.1 Y 1.5 Al 5 O 12 :Ce and Gd 3 Ga 2.3 Al 2.7 O 12 :Ce crystals show well-distinguished TSL and IR OSL properties. • GAGG:Ce crystals show significantly higher TSL and IR OSL intensity and faster IR OSL decay kinetics in comparison with GLYAG:Ce counterpart. [ABSTRACT FROM AUTHOR]

We have designed a novel strategy to develop efficient X-ray-induced long afterglow luminescent materials. Eu3+ ions as electron receptors were chosen as trap creators and emitting centers and scintillator Bi 4 Ge 3 O 12 was regarded as the host to efficiently absorb X-ray. The obtained results showed that Bi 4 Ge 3 O 12 : Eu3+ can produce excellent x-ray induced red long afterglow luminescence which appeared at 589, 612, 655 and 705 nm corresponding to the 5D 0 →7F j (j = 1,2,3,4) transitions, respectively. The best afterglow performance was shown when the Eu3+ doping concentration was 0.5% at this time, and Bi 4 Ge 3 O 12 :Eu3+ also showed a strong afterglow under short-time X-ray excitation. The thermoluminescence results indicated the X-ray irradiation can produce massive secondary electrons and the abundant free electrons can easily induce Eu3+ ions to formed Eu2+* traps, which resulted in the excellent x-ray induced long afterglow luminescence of Bi 4 Ge 3 O 12 : Eu3+. Furthermore, the X-ray induced long afterglow red luminescence from Bi 4 Ge 3 O 12 :Eu3+ can persist for more than 5400 s, which still can be clearly observed by naked eyes even after 5400 s. All these results our designed strategy can realize the development of good X-ray induced long afterglow luminescent materials from scintillator to phosphor. • X-ray excited long afterglow material Bi 4 Ge 3 O 12 :Eu3+ shows red afterglow. • The transformation from scintillator to long afterglow material. • The Eu3+ to Eu2+ transition is responsible for the afterglow of Bi 4 Ge 3 O 12 :Eu3+. • A model is presented to clarify the afterglow mechanisms of Bi 4 Ge 3 O 12 :Eu3+. [ABSTRACT FROM AUTHOR]

Effects of Sc3+ admixture on luminescence and scintillation properties were studied in Ce3+ - doped Lu 2 Y(Al 5-x Sc x)O 12 (x = 1, 1.5, 2) garnet single-crystalline films grown by the isothermal liquid phase epitaxy technique. The Ce3+ photoluminescence (PL) was slightly blue shifted with increasing Sc content due to a decrease in crystal field splitting of the Ce3+ 5d levels. In addition, the thermal activation energy of PL quenching, estimated from the temperature dependence of PL decay times, decreased with increasing Sc content. Lu 2 YAl 4 ScO 12 :Ce exhibited the highest light yield (LY) value of 420 photons/MeV at 5.5 MeV α particles along with a fast scintillation decay time constant (τ e) of 17.4 ns. At room temperature, the decrease of LY value with increasing Sc content could be attributed to the thermal ionization process. • Lu 2 Y(Al 5-x Sc x)O 12 :Ce garnet single-crystalline films were grown by the liquid phase epitaxy technique. • Lu 2 Y(Al 4 Sc)O 12 :Ce exhibits good thermal stability with T q = 400 K. • Activation energy of photoluminescence decreased with increasing Sc content. • Lu 2 Y(Al 4 Sc)O 12 :Ce exhibits light yield (at α-excitation) of 362 photons/MeV and fast scintillation decay time of 17.4 ns. [ABSTRACT FROM AUTHOR]

Excitation spectra (a) and emission spectra (b) of Ba 1.94 P 2 O 7 :0.04Dy3+, 0.02Ce3+ and Ba 1.96 P 2 O 7 :0.04Dy3+. After Dy3+ and Ce3+ are co-doped, Ba 2 P 2 O 7 :Dy3+, Ce3+ phosphors emit the enhanced characteristic blue and yellow emission of Dy3+ with nearly equal intensity under excitation at 323 nm, meaning Ce3+ co-doping increases the symmetry of Dy3+ site as well as the sensitizer. Simultaneously, energy transfer from Dy3+ to Ce3+ is found. [Display omitted] • Ba 2-x-y P 2 O 7 :xDy3+,yCe3+ phosphors were synthesized by calcining the precursor via chemical co-precipitation. • Ba 2 P 2 O 7 :Dy3+, Ce3+ phosphors exhibited the enhanced characteristic blue and yellow emission of Dy3+, and the energy transfer between Ce3+ and Dy3+ was discussed. • Ba 2 P 2 O 7 :Dy3+,Ce3+ phosphors displayed a good thermal stability with a remaining emission intensity of 78% at 250 ℃. In this paper, Ba 2-x-y P 2 O 7 :xDy3+,yCe3+ phosphors are synthesized by calcining the precursor via chemical co-precipitation. The phase structure, excitation and emission spectra, thermal stability, the chromatic performance of phosphors, and energy transfer from Ce3+ to Dy3+ are studied and discussed. The results indicate the samples keep a stable crystal structure as a high-temperature σ-Ba 2 P 2 O 7 phase with two different coordination of Ba2+ sites. Ba 2 P 2 O 7 :Dy3+ phosphors can be effectively excited by 349 nm n-UV light and emit 485 nm blue light and a relatively stronger yellow light peaking at 575 nm, corresponding to 4F 9/2 →6H 15/2 and 4F 9/2 →6H 13/2 transitions of Dy3+, implying that Dy3+ mainly occupies the non-inversion symmetric sites. By contrast, Ba 2 P 2 O 7 :Ce3+ phosphors exhibit a broadband of excitation peaking at 312 nm, and two symmetrical emission peaks at 336 nm and 359 nm from 5d1→4F 5/2 and 5d1→4F 7/2 transitions of Ce3+, showing Ce3+ should merely be presumed to occupy Ba1 site. After Dy3+ and Ce3+ are co-doped, Ba 2 P 2 O 7 :Dy3+, Ce3+ phosphors exhibit the enhanced characteristic blue and yellow emission of Dy3+ with nearly equal intensity under excitation at 323 nm, meaning Ce3+ co-doping increases the symmetry of Dy3+ site as well as the sensitizer. Simultaneously, energy transfer from Dy3+ to Ce3+ is found and discussed. The thermal stability of co-doped phosphors was characterized and briefly analyzed. The color coordinates of Ba 2 P 2 O 7 :Dy3+ phosphors fall in the yellow-green region near the white light, while the emission moves towards the blue-green region after the Ce3+ is co-doped. [ABSTRACT FROM AUTHOR]

Ce3+-doped dense glasses with high light yield (LY) are promising scintillators for use in high-energy particle physics research and radiation sensors for high-energy X- and γ- ray detection. In this work, Ce3+-doped (60-x)SiO 2 -xBaF 2 -20Al 2 O 3 -20Gd 2 O 3 oxyfluoride glasses have been prepared under a CO reducing atmosphere. Substitution of SiO 2 by BaF 2 has been made to increase the density, and the effects on luminescence and scintillation properties have been investigated. The amorphous nature of the prepared glass is confirmed by the XRD profile showing an absence of any diffraction peaks. The broad photoluminescence (PL) emission band of the Ce3+ 5d–4f transition in the 330–580 nm range is observed peaking around 385 nm and the PL decay is governed in the range of 46–53 ns decay time. The 10 mol% BaF 2 glass with density of 4.54 g/cm3 shows the highest LY value of 1590 photons/MeV and energy resolution of 16.5% in the pulse height spectrum of 662 keV γ rays, and the LY of 141 photons/MeV and energy resolution of 21.7% in the pulse height spectrum of 5.5 MeV α particles. • Ce3+-doped (60-x)SiO 2 -xBaF 2 -20Al 2 O 3 -20Gd 2 O 3 (x = 0–20) glasses were prepared under CO atmosphere. • XRD pattern confirms an amorphous nature of the prepared glass. • Gd3+ to Ce3+ energy transfer was observed in the prepared glasses. • Light yield of 1590 photons/MeV at 662 keV γ rays was obtained for 10 mol% BaF 2 containing glass. • Energy transport efficiency in scintillation process increases with increasing BaF 2 content. [ABSTRACT FROM AUTHOR]

The emerging laser-driven phosphor-converted white laser diodes (w-LDs) demand highly efficient and thermally stable color converters. To this end, the Ce3+ luminescence in the rekindled La–Si–O–N host, and the impacts of NH 4 Cl flux and post-processing are investigated systematically. On the basis of the XRD results, well crystalline Ce3+-doped La 5 Si 3 O 12 N and LaSiO 2 N are obtained at 1600 °C for 5 h and 1500 °C for 4 h, respectively. Impressively, the representative La 5 Si 3 O 12 N:0.04Ce3+ and LaSiO 2 N:0.03Ce3+ exhibit a broad excitation band from 240 nm to 400 nm, peaking at around 360 nm, which is well matched with emission from near-UV (n-UV) chip. Under excitation by a n-UV laser, the La 5 Si 3 O 12 N:0.04Ce3+ and LaSiO 2 N:0.03Ce3+ produce bright blue light in a wide emission band from 360 nm to 550 nm. The CIE chromaticity diagram reveals the tunability of the hue of these phosphors. The quenching temperature is determined to be 396 K and 429 K for La 5 Si 3 O 12 N:0.04Ce3+ and LaSiO 2 N:0.03Ce3+ respectively, indicating superior thermal stability. The addition of 3 wt% NH 4 Cl flux much enhances the emission intensity of both La 5 Si 3 O 12 N:0.04Ce3+ and LaSiO 2 N:0.03Ce3+. Furthermore, the post-treatments markedly improve the luminescence properties by increasing the crystallinity, reducing the surface defect, and changing the morphology. Therefore, it is believed that the present work has promising applications in LD lighting and promoting the development of laser display. • Ce3+-activated La–Si–O–N compounds generate bright blue light in a wide emission band of 360∼550 nm pumped by n-UV laser. • The quenching temperature (T 0.5) of Ce3+-doped La–Si–O–N phosphors is 396∼429 K, indicating favorable thermal stability. • As Increasing the NH 4 Cl dosage up to 3 wt%, PL intensity attains a maximum 148–263% of that of the samples without flux. • The post-treatments greatly improve the luminescence by enhancing crystallinity, reducing cluster, and smoothing surface. [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 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]

Luminescence excitation spectra of BaBrI single crystals doped by divalent lanthanide ions are studied using synchrotron radiation excitations from the MAX IV 1.5 GeV storage ring. The energy of the edge and the formation of core cation exciton as well as the energy threshold of the multiplications of electronic excitations is found. It was clearly established the energy transfer from intrinsic luminescence centers to Sm2+ and Eu2+ ions. [ABSTRACT FROM AUTHOR]

Ce-doped garnets find their use as scintillators as well as phosphors. Among synthetic garnets, gallium gadolinium aluminium garnet (GGAG) is a relatively new and interesting material, a mixed garnet that has displayed very good scintillation and luminescence properties. In the presented work Ce-doped GGAG ceramic samples were produced by reaction sintering from commercial oxide powders. The mixed powders were pressed into pellets and sintered. In order to achieve transparency of a ceramic material, it is crucial to eliminate porosity. Therefore, a number of process parameters and their influence on the microstructure and optical quality of the ceramics were studied: starting powders, sintering additives and sintering conditions. The sintering process consisted of two steps, viz. pressureless sintering in air followed by hot isostatic pressing. Luminescence properties of the sintered ceramics were studied by means of photo-luminescence and correlated to the fabrication process parameters. [ABSTRACT FROM AUTHOR]

Europium doped borosilicate glasses were prepared in CO reducing atmosphere. The glasses were systematically investigated through XPS, photoluminescence (PL), fluorescence decay curves and X-ray excited luminescence (XEL). XPS results show that the glasses contain Eu2+ and Eu3+ at the same time. Under the excitation of 360 nm light, only a broad blue emission with peak around 440 nm due to the 5d→4f transition of Eu2+ is observed, while the emissions from Eu3+ do not appear in the PL spectra. The fluorescence decay curves were monitored at 440 nm, and the measured lifetimes are in the range of 0.17–0.42 μs. The PL results indicate that the PL emission from Eu2+ is significantly intense than the PL emissions from Eu3+. Upon X-ray excitation, two main emissions with peaks at 445 nm and 616 nm corresponding to Eu2+ and Eu3+ are obtained. The XEL results reveal that the XEL emissions from Eu3+ are comparably intense as the XEL emission from Eu2+. The results indicate that europium doped borosilicate glass could be a potential scintillating material in X-ray detection filed. [ABSTRACT FROM AUTHOR]

Luminescence spectroscopic properties of lanthanide ions (Ce3+, Pr3+, Gd3+, Tb3+, and Dy3+) doped into Na 3 Y(BO 3) 2 were investigated upon UV-VUV excitation with synchrotron radiation. The positions of 4 f n–15 d state of Ce3+, Pr3+, Tb3+ and Dy3+ in host matrix Na 3 Y(BO 3) 2 were deduced according to the excitation spectra. Crystal-field depression D (A), an important parameter to predict the positions of the lowest 4 f n–15 d levels, was established on the basis of the 5 d levels of Ce3+ in Na 3 Y(BO 3) 2. Then, the average value of D (A) was obtained and further verified for 4 f n–15 d configurations of Pr3+, Tb3+ and Dy3+ in Na 3 Y(BO 3) 2. Finally, the lowest 4 f n–15 d levels of the other trivalent lanthanide ions in Na 3 Y(BO 3) 2 were predicted. The spectroscopic information on 4 f n–15 d levels of lanthanide ions in Na 3 Y(BO 3) 2 may provide new insights useful for designing of new efficient scintillators and WLED phosphors. [ABSTRACT FROM AUTHOR]

The luminescence and scintillation properties of SrI 2 single crystals doped with 5% Eu2+ and 0.05%, 0.2% and 0.5% Sm2+ are evaluated. X-ray excited and photoluminescence measurements show energy transfer from excited Eu2+ ions to Sm2+ ions. At a concentration of 0.5% Sm2+, the luminescence consists almost entirely of 740 nm emission from Sm2+ 5d-4f transitions. Co-doping SrI 2 :5% Eu2+ with Sm2+ provides a novel method to bypass the self-absorption problem encountered in large SrI 2 :Eu2+ crystals and, at the same time, provides a unique near-infrared emitting scintillator with a light yield of approximately 40,000 photons/MeV. [ABSTRACT FROM AUTHOR]

We synthesized 0, 0.02, 0.2, 1.0, and 10% Ce3+ doped CaF 2 AlF 3 AlPO 4 glasses; and then, we evaluated their photoluminescence (PL), scintillation and thermally stimulated luminescence (TSL) properties. Depending on the concentration of Ce3+, PL quantum yield (QY) ranged from 15.8 to 62.8%. When the materials were irradiated by X-rays, scintillation was observed with an emission peak around 330 nm due to 5d→4f transitions of Ce3+. The scintillation decay times ranged 14–25 ns. The glasses showed intense TSL, and the glow peak was broad peaking around 100 °C. The 0.2% and 1.0% Ce3+ doped samples demonstrated high sensitivity with a good linearity over 5 orders of magnitude (0.1 mGy–10 Gy). • We evaluated Ce-doped CaF 2 AlF 3 AlPO 4 glasses PL, Scintillation and TL properties. • 0.2% Ce-doped samples had the highest QY. • By measuring scintillation properties, all Ce-doped samples emitted around 320 nm. • We measured dose response of each sample. [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]

Inorganic scintillation materials have been widely used in several fields, such as high energy physics, nuclear medical imaging and industrial nondestructive inspection. In this work, a novel scintillation material, (Ce x Lu 1-x) 3 Al 5 O 12 /Al 2 O 3 (Ce3+:LuAG/Al 2 O 3) eutectic with different Ce3+-doping concentrations, was successfully grown by the micropulling down method at different pulling speeds. The effects of Ce3+-doping concentration and pulling speed on the microstructure and luminescent properties of the Ce3+:LuAG/Al 2 O 3 eutectic were investigated. The eutectic has a typical garnet structure, and a "Chinese script" microstructure can be seen throughout the cross section. As the pulling speed increased, the grain size and the morphological appearance of the "Chinese script" microstructure decreases. The Ce3+:LuAG/Al 2 O 3 eutectic shows a characteristic Ce3+ emission band centered at 508 nm, and the emission intensity increases with increasing Ce3+-doping concentration until the Ce3+-doping concentration reaches x = 0.01. The eutectic grown at a pulling speed of 1.7 mm/min shows maximum emission intensity, and the light yield of the (Ce 0.01 Lu 0.99) 3 Al 5 O 12 /Al 2 O 3 eutectic excited with X-ray at room temperature is approximately 64% of that of the (Ce 0.01 Lu 0.99) 3 Al 5 O 12 single crystal. The results reveal that the Ce3+:LuAG/Al 2 O 3 eutectic has a potential application as an X-ray detector material. Image 1 • The Ce3+:LuAG/Al 2 O 3 eutectic was firstly grown by the micropulling down method. • The eutectic exhibits garnet structure and typical "Chinese script" microstructure. • The eutectic has high light-yield, short decay time and an X-ray detector material. [ABSTRACT FROM AUTHOR]

The synthesis of efficient nano-scintillators is of great significance for the development of X-ray imaging and other applications. Here, X-ray excited afterglow rare earth nanoparticles β-NaLuF 4 :Gd3+/Tb3+ are investigated. The X-ray-induced luminescence intensity and afterglow duration of NaLuF 4 :Gd3+/Tb3+ nanoparticles are effectively improved by Ca2+ doping. The optimal luminescence and afterglow performance are achieved when Ca2+ doping ratio reaches 10%. The change of crystal field symmetry is the main reason for the improvement of luminescence performance. According to the thermoluminescence curve, it is proved that Ca2+ doping increases the trap concentration and further enhances the afterglow. This study provides the research basis for the application of persistent luminescence materials in biomedical and other fields. • NaLuF 4 :Ca2+/Gd3+/Tb3+ nanoparticles were synthesized by solvothermal method. • The X-ray induced luminescence of NaLuF 4 :Ca2+/Gd3+/Tb3+ NPs were improved by Ca2+ doping. • Afterglow properties were improved after 10% Ca2+ ions doping. [ABSTRACT FROM AUTHOR]

A series of UVA-emitting LaB 3 O 6 :Ce3+ phosphors and La 0.96 Ce 0.04 B 3 O 6 /PMMA films were prepared. The calcining temperature, activator concentration and PL test temperature were studied for the luminescence properties of the phosphor. And the effect of phosphor content on transmittance and X-ray radiation capacity of the composite films was also studied. The results show that LaB 3 O 6 :Ce3+ emits continuous double peaks at 358 nm and 380 nm when excited at 333 nm, the fluorescence lifetime is about 10 ns, and the luminescence intensity at 150 °C is 73.71% of that at room temperature, which can be used as phosphors for UV phototherapy applications. Under X-ray excitation, the integrated intensity of the La 0.96 Ce 0.04 B 3 O 6 /PMMA composite film has a good linear relationship with the X-ray tube current and tube voltage, and the X-ray imaging of a car key taken by La 0.96 Ce 0.04 B 3 O 6 /PMMA composite film has good signal-to-noise ratio, which can be used for X-ray detection and imaging. • A UVA phosphor with good thermal stability can be applied to UV phototherapy. • LaB 3 O 6 :Ce3+ phosphor has no significant afterglow and can be used as scintillator material. • La 0.96 Ce 0.04 B 3 O 6 /PMMA composite film with good X-ray radiation capability can be used for X-ray detection and imaging. [ABSTRACT FROM AUTHOR]

The luminescence and scintillation properties of Ce3+-doped Gd 3 (Al 5-x Sc x)O 12 (x = 1, 1.5, 2, 2.5, 3) garnet crystals grown by the floating zone method were investigated. With increasing Sc content, the Ce3+ 5d 1 → 4f luminescence was blue shifted due to a decrease in 5d 1 -5d 2 crystal field splitting (Δ 12) of the 5d e doublet state. The Sc content showed a strong influence on purity of garnet phase in the Gd 3 (Al 5-x Sc x)O 12 :Ce crystals. The presence of secondary phase (perovskite and/or α-Al 2 O 3) results to a poor transparency and a lower light yield (LY) value. The Gd 3 Al 3 Sc 2 O 12 :Ce crystal exhibited pure garnet phase, highest quantum yield (∼76 %) and transmittance (∼80 %), and highest LY value (6,850 photons/MeV at 662 keV γ rays) among the studied samples. Above RT, a decrease of radioluminescence (RL) yield occurs for all samples due to the thermal ionization process. A decrease of the RL yield at low temperature observed in correlation with the intense thermoluminescence peaks can be explained by the localization of electrons at intrinsic shallow traps. • Luminescence and scintillation characteristics of Gd 3 (Al 5-x Sc x)O 12 :Ce crystals are investigated. • Temperature dependence of radioluminescence yield is measured in 10–350 K range. • Gd 3 Al 3 Sc 2 O 12 :Ce shows highest quantum yield and light yield. • Thermoluminescence and low-temperature afterglow are investigated. [ABSTRACT FROM AUTHOR]

In this research, melt quenching was used to prepare Dy3+ ion doped alkaline borophosphate glasses. According to the XANES measurement, Dy ions in glass show +3 oxidation state, identical to the standard Dy 2 O 3 powder. Glasses were measured for density (ρ), molar volume (V m), and refractive index (n). The absorption peaks, which are assigned to transitions from the ground state 6H 15/2 to higher energy levels of Dy3+ ion in glass matrix. Four prominent emission bands were observed in luminescence spectra, which correspond to the 4F 9/2 →6H J (J = 15/2, 13/2, 11/2, 9/2) transitions. The Judd-Ofelt (J-O) intensity parameters follow the trend as Ω 2 >Ω 6 >Ω 4 of the PBLAGdDy 1.0. For the stimulated emission cross-section and branching ratio (>0.5), 4F 9/2 → 6H 13/2 transition was found to be higher than other transitions. Because the decay curves of glasses with different concentrations of Dy3+ ion were found to be non-exponential, these glasses were calculated using the Inokuti-Hirayama (I-H) model. The obtained photoluminescence and decay times spectra primarily showed energy transfer effects from Gd3+ to Dy3+ ions and the calculated values of energy transfer efficiency (η) found that the values increased, which confirms energy transfer from Gd3+ to Dy3+ ions. From this study, the current glasses could be useful in the applications of solid-state lasers, LEDs, and scintillation materials. • P 2 O 5 +B 2 O 3 +Al 2 O 3 +Li 2 O + Gd 2 O 3 +Dy 2 O 3 glasses have been prepared by melt quenching method. • The highest emission intensity is 1.0 mol% of Dy3+ ions. • The energy transfer efficiency (η) found an increase with Dy 2 O 3 contents. • The integral scintillation efficiency was found in 20% of the BGO crystal. [ABSTRACT FROM AUTHOR]

Abstract The paper discusses the possible processes of radiation-induced changes that occur during irradiation of composite scintillators containing grains of inorganic crystals, and investigates the effect of these processes on radiation resistance of composite systems. All crystalline inorganic scintillation materials contain defects, which can play the role of quenching centres. An irradiation destroys and changes not only the main material of a scintillator but such the centres as well. As a result, the luminescence intensity can grow for a while due to weakening the effect of quenching. In this case, the luminescence spectrum of a scintillator does not change its shape under various accumulated doses D because no new luminescence centres appear. A modification of the properties of the luminescence centres arising under the action of irradiation has to lead to a change in the spectral characteristics of the luminescence. Therefore, the appearance or absence of such the changes is evidence of which centres are predominantly damaged because of irradiation with given dose D. The paper as well discusses the possibilities of obtaining radiation-resistant materials for the development of wavelength shifting light guides for composite scintillators. We investigated samples based on non-luminescent transparent silicone elastomer containing p -terphenyl or 1,4-di[2-(5-phenyloxazolyl)]benzene (POPOP) molecules. [ABSTRACT FROM AUTHOR]

Abstract The work is dedicated to the investigation of the luminescent and scintillation properties of the LiLuP 4 O 12 :Ce tetraphosphate, as a new scintillation material. The LiLuP 4 O 12 :Ce polycrystalline samples were grown by the Micropulling down (MPD) method. Under e-beam excitation and excitation with energy above the band gap of host, the LiLuP 4 O 12 :Ce crystals possess very strong Ce3+ luminescence in the UV range in the bands peaked at 334 and 355 nm with a lifetime of 23 ns at room temperature. We have found that the scintillation light yield (LY) of polished plates prepared from MPD grown LiLuP 4 O 12 :Ce samples is relatively high and comparable with the LY of reference BGO crystal. Future improvement of the scintillation LY is expected at the optimization of the growth conditions of this compound. The energy structure of Ce3+ ions, related to the 4f-5d transitions of Ce3+ ions in the 3.7–25 eV range, was determined from the excitation and emission spectra of LiLuP 4 O 12 :Ce crystal under excitation by synchrotron radiation. We have also determined the energy of creation of excitons bound with Ce3+ ions and estimated the energy gap in LiLuP 4 O 12 host, which is equal to 8.5 and > 9.0 eV, respectively. [ABSTRACT FROM AUTHOR]

Time-resolved luminescence of YAG-Ce (150 ppm) fiber crystal with Mg co-doping was studied under pulsed X-ray excitation and γ-rays (Cs 662 keV). The initial part of decay kinetics under X-ray excitation is faster than for direct cerium excitation (63 ns). Decay kinetics is also characterized by the presence of slow components with at least two characteristic times longer than Ce3+ radiation time. The slowest one which dominates for t > 500 ns in YAG-Ce without Mg co-doping practically vanishes for samples with 50 ppm co-doping. Decay kinetics under γ-rays are characterized by slower rise time than that under X-rays. These properties can be explained by competition of energy transfer and energy losses in track regions. The distribution of excitations in tracks produced by X-rays differs from that in tracks produced by γ-rays, since the energy of primary electron after γ-quantum conversion is much higher than after X-ray absorption. The stopping power for energetic electrons decreases with increase of electron energy, and therefore the density distribution after X-ray conversion is shifted to higher densities, Therefore, the acceleration of recombination and quenching of excitations is more prominent under X-ray excitation. Specific role of Ce4+ induced by Mg co-doping is also discussed in the paper. • Samples YAG-Ce,Mg grown by micro-pulling-down were studied under X-ray and γ-rays. • Luminescence decay becomes faster with increase of Mg concentration. • Slow component vanishes for samples with 50 ppm Mg co-doping. • Decay kinetics under γ-rays show rise part and is slower than under X-rays. • The difference is explained using of the excitation densities distribution in track. [ABSTRACT FROM AUTHOR]

The scintillation characteristics of Gd 3 Al 2 Ga 3 O 12 :Ce, Li (GAGG:Ce,Li) and Gd 3 Al 2 Ga 3 O 12 :Ce, Mg (GAGG:Ce,Mg) single crystals were compared. Radioluminescence spectra and photoluminescence decay curves were measured at various temperatures between 77 and 500 K to investigate the thermal luminescence quenching. At 662 keV γ rays, the LY value of 35,400 photons/MeV and energy resolution of 6.9% obtained for GAGG:Ce, Li are superior to those of 24,200 photons/MeV and 9.5% for GAGG:Ce,Mg. Scintillation decays are approximated by a double exponentials with a fast principal decay component of 47 ns (83%) for GAGG:Ce, Mg and 90 ns (86%) for GAGG:Ce,Li. Coincidence time resolution of 282 ps obtained for GAGG:Ce, Mg is better than that of 389 ps for GAGG:Ce,Li. GAGG:Ce, Mg shows a much lower afterglow and thermally stimulated luminescence intensity with respect to GAGG:Ce,Li. • Scintillation properties of Li+ and Mg2+ -codoped Gd 3 Al 2 Ga 3 O 12 :Ce are compared. • Gd 3 Al 2 Ga 3 O 12 :Ce, Mg exhibits better timing performance. • Gd 3 Al 2 Ga 3 O 12 :Ce, Mg shows lower afterglow and TSL intensity. • Gd 3 Al 2 Ga 3 O 12 :Ce, Li exhibits high light yield and good energy resolution. [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]

Abstract Single crystal scintillators of RE 2 O 3 :Eu (RE = Lu, Y, Sc) with high (8%) and low (1%) Eu doping concentration were grown by the optical floating zone method. The luminescence and scintillation properties have been investigated and compared thoroughly. Correlated measurements of afterglow curves, photoluminescence excitation and photoluminescence, photoluminescence decay curves and X-ray excitation curves were performed. Lu 2 O 3 :Eu and Y 2 O 3 :Eu present significant afterglow intensity decreasing after high Eu concentration doping. While for the Sc 2 O 3 :Eu, its afterglow intensity even increases slightly. The luminescence efficiencies of high doping concentration samples are weaker than that of the low concentration ones due to the concentration quenching. The integrated X-ray excitation luminescence reveals the scintillation luminescence efficiencies of samples with the high concentration or the low ones both have the following sequence:Lu 2 O 3 :Eu＞Y 2 O 3 :Eu＞Sc 2 O 3 :Eu. Highlights • RE 2 O 3 :Eu (RE = Lu,Y,Sc) single crystal scintillators are grown by optical FZ method. • Sc 2 O 3 :Eu present different afterglow behavior comparing with Lu 2 O 3 :Eu and Y 2 O 3 :Eu. • The relationship between afterglow and Eu(S 6).→Eu(C 2) energy transfer is discussed. [ABSTRACT FROM AUTHOR]

Purpose: The goal of this work is to produce a surface-dosimetry method capable of accurately and remotely measuring skin dose for patients undergoing total skin electron therapy (TSET) without the need for postexposure dosimeter processing. A rapid and wireless surface-dosimetry system was developed to improve clinical workflow. Scintillator-surface dosimetry was conducted on patients undergoing TSET by imaging scintillator targets with an intensified camera during TSET delivery.Methods and Materials: Disc-shaped scintillator targets were attached to the skin surface of patients undergoing TSET and imaged with an intensified, time-gated, and linear accelerator-synchronized camera. Optically stimulated luminescence dosimeters (OSLDs) were placed directly adjacent to scintillators at several dosimetry sites to serve as an absolute dose reference. Real-time image-processing methods were used to produce background-subtracted intensity maps of Cherenkov and scintillation emission. Rapid conversion of scintillator-light output to dose was achieved by using a custom fitting algorithm and calibration factor. Surface doses measured by scintillators were compared with those from OSLDs.Results: Absolute surface-dose measurements for 99 dosimetry sites were evaluated. According to paired OSLD estimates, scintillator dosimeters were able to report dose with <3% difference in 88 of 99 observed dosimetry sites and <5% difference in 98 of 99 observed dosimetry sites. Fitting a linear regression to dose data reported by scintillator versus OSLD, per dosimetry site, yielded an R2 = 0.94.Conclusions: Scintillators were able to report dose within <3% accuracy of OSLDs. Imaging of calibrated scintillator targets via an intensified, linear accelerator-synchronized camera provides rapid absolute surface-dosimetry measurements for patients treated with TSET. This technique has the potential to reduce the amount of time and effort necessary to conduct full-body dosimetry and can be adopted for use in any surface-dosimetry setting where the region of interest is observable throughout treatment. [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 Eu3+ doped tellurite scintillating glasses were prepared by the conventional melt-quenching method. The physical and luminescent properties of glasses were investigated by DTA, density, transmittance spectra, photoluminescence spectra, and X-ray excited luminescence (XEL) spectra. The densities of the glasses are in the range from 5.89 g/cm3 to 6.05 g/cm3. The glasses exhibit intense red emissions upon 393 nm light and X-ray excitations. The maximum integral XEL intensity of the glasses is about 6% of that of commercial Bi 4 Ge 3 O 12 (BGO) scintillating crystal. The results reveal that Eu3+ doped tellurite glass could be a scintillator candidate used in X-ray detection field. [ABSTRACT FROM AUTHOR]

Abstract We examined the optical and luminescence properties of BaO-TiO 2 -SiO 2 (BTS) glasses and BTS glass-ceramics (GCs). The 40BaO-20TiO 2 -40SiO 2 (BTS40) GC obtained by heat treatment at glass transition temperature (T g) + 50 °C exhibited bulk crystallization, whereas surface crystallization was obtained for the 33.3BaO-16.7TiO 2 -50SiO 2 (BTS50) and 30BaO-15TiO 2 -55SiO 2 (BTS55) GCs by the same heat treatment. The photoluminescence (PL) excitation spectra changed depending on the chemical composition. After crystallization, the peaks of the PL and the scintillation spectra were blue-shifted, indicating the local coordination change of the Ti species. A large enhancement of X-ray induced scintillation was observed in the BTS40 system, though the precursor BTS40 glass exhibited lower scintillation intensity despite its higher effective atomic number (Z eff). Since the volume fraction of Ba 2 TiSi 2 O 8 crystallites in the BTS40 GC is higher than the other GCs, the enhancement in scintillation intensity reflects an increase in number density of emission centers in Ba 2 TiSi 2 O 8 crystallites after crystallization. Highlights • BaO-TiO 2 -SiO 2 glasses were prepared by a melt-quenching method. • Heat-treatment of glasses was performed at the T g + 50 °C to obtain the glass-ceramics. • Volume fraction of Ba 2 TiSi 2 O 8 decreased with increasing SiO 2 fraction. • Intensity of emission, especially X-ray scintillation, was affected by the Ba 2 TiSi 2 O 8 volume fraction in the glass-ceramics. [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]

Abstract The glass phosphor thermoluminescence (TL) properties of zinc borate silica (ZBS:45ZnO-45B 2 O 3 –10SiO 2) doped with various concentrations of Cu 2 O and then co-doped with various SnO 2 was analyzed. The doped sample with 0.005% Cu 2 O concentration and co-doped with 0.1 mol% SnO 2 have a higher TL response among the other concentrations for a delivered dose 50 Gy of Cobalt-60 gamma radiation. The obtained glow curve from the optimum doped and co-doped samples with 0.005% Cu 2 O and 0.1 mol% SnO 2 concentrations are simple with single glow peak. The annealing procedure and heating rate are determined for both optimum samples. TL response within the dose range of 0.5–100 Gy, minimum detectable dose, reproducibility and fading are investigated. Based on analyses of glow curve, linearity, reproducibility, dose threshold, thermal fading, optical bleaching and activation energy frequency factor, the glass with co-doped 0.1 mol% SnO 2 found to be suitable as a thermoluminescence dosimeter. [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]

Large-sized γ-CuI single crystals with ultrafast scintillation property were grown in LiI acetonitrile solvent through evaporation technique. The LiI exhibits unique properties to γ-CuI single crystal preparation. One is that it increases the solubility of CuI in the solvent, which gives rise to a largest-sized (23 × 14 × 2 mm 3 ) single crystal with the high optical transmission (over 60%) in the wavelength region of 435–800 nm. The other feature is that it acts as an effective isoelectronic dopant and improves the molar ratio of copper to iodine, which greatly enhances the near-band-edge emissions (411 and 432 nm) and suppresses the broadband emission (680 nm). The decay time of the fast emission under pulsed X-ray excitation is shorter than 450 ps. The results will give a guidance for optimizing the properties of γ-CuI single crystal as an ultrafast scintillator. [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]

Abstract The pixelated scintillation screen as an important component of the X-ray imaging detector effectively solves the issue of the lateral spreading of scintillation light and improves the spatial resolution of X-ray imaging. In this work, the hexagonal as well as square arranged pixelated CsI scintillation screens based on the silicon pore templates with pore pitch about 4 μ m and diameter about 3 μ m were fabricated by vacuum melting injection method. The morphology, crystallinity, X-ray excited optical luminescence and X-ray imaging performance of the screens were investigated. The results show that the CsI scintillator was filled into the silicon pore templates uniformly and compactly without microbubbles even if the depth of the filled CsI microcolumns reaches 100 μ m. The pixelated scintillation screen exhibits good CsI crystallinity with (110) preferred orientation. The intensity of X-ray excited optical luminescence of the hexagonal arranged pixelated CsI scintillation screen increases by 14.3% compared with that of the square arranged screen with same thickness. Furthermore, the intensity of the pixelated CsI screen with 100 μ m thickness is 34.1% higher than that of the screen with 40 μ m thickness. The spatial resolution of the X-ray imaging system with the hexagonal arranged pixelated CsI scintillation screen is about 115 lp/mm and not sensitive to the screen thickness, which is 11.5% higher than that with the square arranged screen. The detective quantum efficiency of the system with the hexagonal arranged pixelated CsI scintillation screen appears relatively higher than that with the square arranged screen with same thickness and increases with the thickness of the screen. This means the X-ray imaging performance of the hexagonal arranged pixelated CsI scintillation screen is better than that of the square array arranged screen. Highlights • The hexagonal arranged pixelated CsI scintillation screens without microbubbles were successfully fabricated by vacuum melting injection method. • The spatial resolution of the X-ray imaging system with the hexagonal arranged pixelated CsI scintillation screen is about 115 lp/mm. • The intensity of X-ray excited luminescence of the hexagonal arranged pixelated CsI scintillation screen increases by 14.3% compared with the same thickness square arranged screen. [ABSTRACT FROM AUTHOR]

CaMoO 4 crystal is a promising scintillator for investigating the neutrinoless double beta decay process and is commonly grown by the Czochralski method. In this study, CaMoO 4 single crystals were grown by the vertical Bridgman method using both spontaneous crystallization and seed crystal approaches. The CaMoO 4 crystal grown using the spontaneous crystallization approach exhibited yellow, light blue, and deep blue colours (from top to middle part of the ingot). The thermal expansion coefficients, α a and α c , were calculated to be 6.11 × 10 −5 /°C, and 23.58 × 10 −5 /°C, respectively. The optical transmission spectra and photo- and thermally stimulated luminescence spectra of the crystals before and after thermal annealing were also investigated. The yellow cubic CaMoO 4 crystal showed the highest x-ray-stimulated luminescence intensity and the best light output under the excitation of a 137 Cs radioactive source. [ABSTRACT FROM AUTHOR]

LiAlO 2 can be considered as a good candidate for neutron scintillator host matrix due to the high Li content and high energy deposit of reaction of 6 Li isotope with neutron. Low density (2.75 g/cm 3 ) is of advantage to achieve low sensitivity of background gamma radiation in mixed radiation fields. Ti-doped LiAlO 2 shows relatively high neutron light yield comparable to that of the Li-glass standard neutron scintillator. At room temperature the Ti 4+ charge transfer (CT) luminescence at 375 nm with the 2.5 µs decay time is the leading emission process. Besides the CT luminescence host emission at shorter wavelengths (350 nm), defect-related emission at 440 nm and impurity Fe 3+ luminescence at 740 nm are observed. Their emission spectra, excitation spectra and decay kinetics including temperature dependences were studied. Luminescence mechanism in the material and interplay between the luminescence processes are discussed together with possible role of nonstoichiometry and Mg codoping. [ABSTRACT FROM AUTHOR]

This paper deals with the study of 1-phenyl-3-(2,4,6-trimethyl-phenyl)-2-pyrazoline, 2,2´,7,7´-tetrakis(N,N-diphenyl-amino)-9,9´-spirobifluorene, 2-(4-biphenylyl)−6-phenylbenzoxazole and 9,9´-bifluorenyl as possible replacements of the existing and most widely used luminophore (2.5-diphenyloxazole (PPO)) in contemporary scintillators. The study is focused on the determination of emission wavelength, concentration optimization, the influence of the wavelength shifters POPOP and bis -MSB. In addition, the response to alpha and beta radiation were measured, in particular, the pulse length index (PLI) was determined. Finally, yet importantly, the effect of emulsifiers on the shape of the spectrum and the solubility of the aqueous phase was tested. The results obtained were compared with the commercially available Aqualight scintillation cocktail. [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]

Photoluminescence and thermally stimulated luminescence of Gd 3 (Ga,Al) 5 O 12 :Ce single crystals and epitaxial films co-doped with different concentrations of Mg 2+ ions are investigated in the 77–500 K temperature range under excitation in the 4f - 5d 1 and 4f - 5d 2 absorption bands of Ce 3+ ions. Influence of Mg 2+ ions on the photoluminescence intensity, spectrum, decay kinetics, temperature dependence of the photoluminescence intensity, and the activation energy of luminescence thermal quenching is observed. Co-doping with Mg 2+ is shown to result in a drastic reduction of the afterglow and thermally stimulated luminescence and in a strong shortening of the afterglow decay kinetics. It influences also defects creation spectra and the activation energy of the photostimulated defects creation. The Mg 2+ - induced changes in the characteristics of the Gd 3 (Ga,Al) 5 O 12 :Ce, Mg single crystals and epitaxial films are found to be strongly different, and possible reasons of these differences are discussed. [ABSTRACT FROM AUTHOR]

The Tb 3+ /Yb 3+ co-doped BaO-WO 3 -SiO 2 glass ceramic is prepared by melt crystallization method. The optimum heat treatment schedule is determined on basis of differential scanning calorimetry. The crystal phase is BaWO 4 by X-ray diffraction analysis. The crystal grain sizes are examined by scanning electron microscope and crystal grain sizes increase with the increasing of heat treatment time. In the visible region, the transmittance of glass ceramic is 79%. The up-conversion fluorescence intensity increase with the increasing of heat treatment time up to 90 min and with the increasing of Yb 3+ concentration up to 0.3 mol%. The possible mechanism of up-conversion in Tb 3+ /Yb 3+ co-doped BaWO 4 glass ceramic is discussed. [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]

The linear response is the key property employed by a radiation detector to determine the accurate intensity of a pulse radiation field. In this study, we investigated the high fluence rate response behavior of a LaBr 3 scintillator. We used a high-intensity pulsed X-ray source called “QiangGuang-I” which could produce an X-ray pulse with a total dose of 100 Gy, full width at half maximum of 20 ± 5 ns, and an average energy of 1 MeV, to test the linear response of the LaBr 3 scintillator. The Lissajous figure method was used in this experiment. The results showed that the fluence rate linear response limit was more than 1.8 × 10 20 MeV/(cm 2 ·s). [ABSTRACT FROM AUTHOR]

Composite films of CdWO 4 embedded in polystyrene have been prepared and characterized through microtomography, photoluminescence and X-ray excited optical luminescence. CdWO 4 scintillator powder was successfully produced via microwave-assisted hydrothermal method using oxide precursors. With the control of synthesis pH, CdWO 4 wolframite structure was obtained at temperatures as low as 100 °C for reaction time of 1 h. Surface modification of CdWO 4 particles by stearic acid promoted good dispersion of scintillator nanoparticles within the polymeric matrix. The composites have been prepared with 220 µm or 440 µm thickness and CdWO 4 /PS mass ratios of 10% and 20%. Optical measurements show the characteristic CdWO 4 emission in the blue region as well as PS luminescence due to PPO, POPOP and PTO organic impurities. Under X-ray excitation, the light output was proportional to the increase of scintillator content and sample thickness. The emission intensity varied for each film face irradiated, being the most homogeneous condition achieved for the composite of 440 µm and CdWO 4 /PS = 10%. [ABSTRACT FROM AUTHOR]