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High-energy radiation detection and imaging technology has significant applications in high-energy physics research, medical imaging, and industrial monitoring. Lead-free metal halides exhibit exceptional potential for conducting indirect detection of high-energy radiation due to their characteristics of low toxicity, strong stability, high light yield, and large Stokes shift. This paper reviews the most recent advances in lead-free metal halide scintillator materials for X-ray imaging. Subsequently, it lists the most important parameters of scintillator performance and introduces the production procedures for single crystal, powder, and nanocrystal scintillators. Furthermore, it discusses the manufacturing of scintillator films with improved performance, focusing on large-area flexible scintillator films and the coupling with microstructures. Finally, it discusses current challenges and opportunities for enhancing X-ray imaging using lead-free metal halide scintillator materials. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of cerium-doped lanthanum fluoride (La(1−x)CexF3) nanocrystals have been carried out. The surfaces of La(1−x)CexF3 nanocrystals were modified with oleic acid using the co-precipitation technique, and then doped with cerium with various mole fractions (x) = 0.05, 0.10, 0.15, 0.20, and 0.25. The nanocrystals produced were characterized for their crystal structure using x-ray diffraction (XRD), their morphology by transmission electron microscopy (TEM), their functional group identification using Fourier-transform infrared (FTIR), and Raman spectroscopy, and their photoluminescence behavior using photoluminescence (PL) spectroscopy. Detailed investigations revealed that, based on the XRD data and TEM images, La(1−x)CexF3 exhibits trigonal-structured nanocrystals with the symmetry space group P-3c1. Among the samples, La0.75Ce0.25F3 exhibited the sharpest PL peak. The PL spectra for La0.75Ce0.25F3 nanocrystals excited at 370 nm and showed an intense emission peak at 495 nm with a lifetime τ = 1.523 × 10−10 s. This emission was assigned to the 5d → 4f (2F5/2 and 2F7/2) transitions of Ce3+ energy levels, indicating a luminescence center mechanism. These results indicate that the synthesized La0.75Ce0.25F3 is a promising phosphor material for detector scintillators. [ABSTRACT FROM AUTHOR]

Radiation detection plays an important role in diverse applications, including medical imaging, security, and display technologies. Scintillators, materials that emit light upon exposure to radiation, have garnered significant attention due to their exceptional sensitivity. Previous research explored polymer dots (P-dots) doped with iridium complexes as nano-sized scintillators for radiation detection, but these were constrained to emitting specific colors like red, green, and blue, limiting their utility. Recently, there has been a breakthrough in the development of white light emitters stimulated by UV–visible light. These emitters exhibit a broad spectral range in the visible wavelength, enhancing contrast and simplifying detection by visible-light sensors. Consequently, the quest for white color scintillators in radiation detection has emerged as a promising avenue for enhancing scintillation efficiency. In this study, we present a novel approach by applying P-dots doped with two iridium complexes to create white light-emitting nano-sized scintillators. These scintillators offer a wider spectral coverage within the visible-light wavelength range. Under UV light (365 nm) excitation, our synthesized P-dots exhibited remarkable white light emission. Moreover, when excited by electron beam irradiation, we observed the clear emission close to white emission which is valuable for improving the detection of radiation. [ABSTRACT FROM AUTHOR]

There is a growing demand for materials for detecting ionizing radiation, which has led to the expansion of research and development of new scintillators. Typically, scintillators are synthesized by crystallizing materials at high temperatures, and their photoluminescence (PL) is difficult to tune in the visible spectral range. Therefore, composite materials based on CsPbBr3 perovskite nanocrystals (PNCs), which have a high average atomic number and a long charge-carrier diffusion length, are of particular interest and may be used for detecting ionizing radiation. Unlike bulk scintillators, PNCs are synthesized in solution at relatively low temperatures, with the PL tunable throughout the visible spectrum. The main problem limiting the widespread use of PNCs is their low stability upon contact with the environment. This study presents the results of experiments on the encapsulation of PNCs in a polystyrene matrix, the evaluation of the changes in the luminescence quantum yield (QY) over time, and the development of a technique for studying the amplitude characteristics of signals recorded during the interaction of α-particles with composite materials based on CsPbBr3 PNCs and polystyrene. The study has shown that composite samples based on PNCs and polystyrene retain a stable luminescence QY for two weeks. Using a 241Am source with a characteristic α-particle energy of about 4.6 MeV and γ-ray energy of 60 keV, the light output values were calculated for the samples studied. The maximum light output was 20% of that of the standard "fast" plastic scintillator (POPOP) at a volume fraction of PNCs in the composite of less than 1%, which indicates the prospect of PNCs as a basis for composite scintillators and their further use in X-ray diagnosis. [ABSTRACT FROM AUTHOR]

Luminescence clusters composed of organic ligands and metals have gained significant interests as scintillators owing to their great potential in high X-ray absorption, customizable radioluminescence, and solution processability at low temperatures. However, X-ray luminescence efficiency in clusters is primarily governed by the competition between radiative states from organic ligands and nonradiative cluster-centered charge transfer. Here we report that a class of Cu4I4 cubes exhibit highly emissive radioluminescence in response to X-ray irradiation through functionalizing biphosphine ligands with acridine. Mechanistic studies show that these clusters can efficiently absorb radiation ionization to generate electron-hole pairs and transfer them to ligands during thermalization for efficient radioluminescence through precise control over intramolecular charge transfer. Our experimental results indicate that copper/iodine-to-ligand and intraligand charge transfer states are predominant in radiative processes. We demonstrate that photoluminescence and electroluminescence quantum efficiencies of the clusters reach 95% and 25.6%, with the assistance of external triplet-to-singlet conversion by a thermally activated delayed fluorescence matrix. We further show the utility of the Cu4I4 scintillators in achieving a lowest X-ray detection limit of 77 nGy s−1 and a high X-ray imaging resolution of 12 line pairs per millimeter. Our study offers insights into universal luminescent mechanism and ligand engineering of cluster scintillators. X-ray luminescence efficiency of copper halide clusters is limited by nonradiative charge transfer. Here, Zhang et al. report highly emissive radioluminescence of Cu4I4 cubes by functionalizing biphosphine ligands with acridine, unlocking the potential use as low-cost and eco-friendly scintillators. [ABSTRACT FROM AUTHOR]

Thin luminescent films of the organometallic complex of lithium 8-hydroxyquinolate Liq on glass substrates were fabricated by capillary deposition and lithography. The spectral-luminescent properties of the obtained film structures were investigated. The film surface was analyzed. The light yield and the kinetics of scintillation emission of the obtained film structures are estimated. [ABSTRACT FROM AUTHOR]

For the first time, terbium-activated gadolinium tantalo-niobates were synthesized ((Gd1‒xTbx)NbyTa1–yO4). The synthesis was carried out by the liquid-phase method. All studied materials had the main crystalline modification M GdNbO4. The content of impurity phases did not exceed 2–5%. The photo- and cathodoluminescence spectra were studied. Concentration quenching of the terbium ion luminescence for a series of solid solutions containing tantalum ((Gd1–xTbx)Nb0.9Ta0.1O4) occurs earlier than for pure gadolinium niobates ((Gd1–xTbx)NbO4). The obtained materials are promising for use as scintillators. [ABSTRACT FROM AUTHOR]

CsPbBr3 perovskite nanocrystals (PNCs) are the focus of recent basic and applied research, with special emphasis on their use in photovoltaic cells, hybrid light-emitting diodes, single-photon sources, basic elements of optical computers, and other optoelectronic devices. The main problem limiting the use of PNCs is their low stability under normal conditions. Development of composite materials where PNCs are embedded in polymer matrices is an approach to solving the problem of the stability of PNCs contacting the atmosphere. Here, we report the results of experiments on designing composite thin films (TFs) consisting of PNCs and modified polymethyl methacrylate (PMMA). Specifically, samples of durable TFs containing CsPbBr3 with a high photoluminescence quantum yield have been engineered, optimal parameters (including the spinning time, spinning rate, and concentration) for the spin-coating fabrication of the TFs have been found, and the TFs with a highly homogenous film coating have been obtained. This last factor is an important criterion for the use of PNC–PMMA composite as an active layer in quantum dot light-emitting diodes (QDLEDs). In addition, since PNCs are promising as a basis for the scintillating coating of detectors, whose performance depends on the homogeneity of the luminophore distribution within the scintillator (e.g., a CCD array), the results of this study could be used in developing X-ray detectors for medical applications. [ABSTRACT FROM AUTHOR]

In recent years, Cs2ZnCl4 crystal has become an ideal substrate for various functional doped ions due to its large bandgap, showing potential in photodetectors and scintillators. In practical application, the intrinsic defect luminescence of bulk crystals has an important effect on the photoelectrical properties. In this work, Ø12 mm × 90 mm Cs2ZnCl4 single crystal was grown by the vertical Bridgman method. The theoretical bandgap, state density distribution, and refractive index curve of the crystal were obtained by first-principles calculation of the structure data. The luminescence properties of the crystal were characterized, including photoluminescence spectrum and radioluminescence spectrum. The temperature-dependent photoluminescence spectrum of the crystal was studied, and the luminescence process of the defects in the crystal was analyzed by the experimental results. [ABSTRACT FROM AUTHOR]

The effect of CeF3 concentration and γ-irradiation on the physical, optical and luminescence properties of Gd2O3–B2O3–CeF3 glasses were studied in this work. Before irradiation, the addition of CeF3 in glass degraded the network connectivity observed from FTIR and possibly created the non-bridging oxygen (NBO) in glass structure. This NBO caused the reduction of Ce3+/Ce4+ ratio in XANES, the red-shift in transmission spectra and the raise of refractive index with addition of CeF3 content. Such red-shift also was influenced by 4f–5d transition of Ce3+ dopant. This ion generated the strongest photoluminescence (PL) and radioluminescence (RL) in 0.3 mol% CeF3-doped glass with nanoseconds decay time. The irradiation with γ-rays damaged the glass structure, broke the chemical bonds, and created color center in the glass network. The non-bridging oxygen hole center (NBOHC), that absorbed photons in the visible light region, caused the darkening, color change and increment of refractive index. These irradiation effects on glass were mitigated by the addition of CeF3 that the electron donation of Ce3+ decreased the number of NBOHC. The Ce3+/Ce4+ ratio in most glasses after irradiation then reduced compared to them before irradiation, resulting to the decrease in PL and RL intensity. Our results confirm that CeF3 can enhance the radiation hardness of glass and the 0.3 mol% CeF3-doped glass is a promising glass scintillator. [ABSTRACT FROM AUTHOR]

We evaluated the photoluminescence (PL), scintillation, and dosimetric properties of Ce–doped Mg2SiO4 single crystals. As the PL and optically-stimulated luminescence (OSL) properties, the Ce–doped Mg2SiO4 showed the emission from 5d to 4f transitions of Ce3+. In the scintillation and thermally-stimulated luminescence (TSL) properties, two emission peaks due to Ce3+ and defect centers were observed. The Ce–doped Mg2SiO4 showed OSL by stimulating at 600 nm and TSL by heating at 50, 160, 195, and 370 °C. In OSL, linearly proportional responses were confirmed from 10 mGy for the 0.5 and 1% Ce–doped samples to 100 mGy for the 0.1% Ce–doped sample. In TSL, the undoped and Ce–doped samples had the linearity response from 100 to 0.01 mGy, respectively. [ABSTRACT FROM AUTHOR]

Fluorescent type nuclear battery consisting of scintillator and photovoltaic device enables semipermanent power source for devices working under harsh circumstances without instant energy supply. In spite of the progress of device structure design, the development of scintillators is far behind. Here, a Cs3Cu2I5: Mn scintillator showing a high light yield of ~67000 ph MeV−1 at 564 nm is presented. Doping and intrinsic features endow Cs3Cu2I5: Mn with robust thermal stability and irradiation hardness that 71% or >95% of the initial radioluminescence intensity can be maintained in an ultra-broad temperature range of 77 K-433 K or after a total irradiation dose of 2590 Gy, respectively. These superiorities allow the fabrication of efficient and stable nuclear batteries, which show an output improvement of 237% respect to the photovoltaic device without scintillator. Luminescence mechanisms including self-trapped exciton, energy transfer, and impact excitation are proposed for the anomalous dramatic radioluminescence improvement. This work will open a window for the fields of nuclear battery and radiography. Fluorescent-type nuclear batteries are a promising semi-permanent power source, but performance is hindered by scintillator development. Here the authors report a scintillator with high light yield and stability, which leads to improved performance. [ABSTRACT FROM AUTHOR]

The neutron energy spectrum is one of the most important characteristic parameters. A novel optical measurement method is proposed. The purpose of the method is to determine the neutron spectra according to the recoil proton track length. The recoil protons deposit energy along the track and excite scintillator luminescence. The luminescence image directly reflects the neutron energy spectra. The Geant4 simulation toolkit is used to study the characteristics of the recoil proton luminescence distribution and determine the detector system response. A reconstruction algorithm based on the potential reduction interior point is developed and applied to spectrum unfolding. This method has the advantages of an intuitive measurement, good energy resolution, suitability for various charged particle beams, a wide energy range, convenience, and an adjustable range. [ABSTRACT FROM AUTHOR]

Although imaging techniques using soft X-rays (SXs) are being developed as the available photon flux increases because of the continuing development of synchrotron light sources, it will be necessary to downsize the pixel size of the SX camera to produce finer SX images. Application of the stimulated emission depletion (STED) method to a scintillator plate followed by use of this plate as a sensor is one promising method to reduce the pixel size of SX cameras. A STED phenomenon occurred in the luminescence of a Ce-doped Lu2SiO5 crystal (Ce:LSO) excited using ultraviolet (UV) light when the scintillator was irradiated with azimuthally polarized laser light in the photon energy range from 1.97 eV (630 nm) to 2.58 eV (480 nm). When the excitation light source changed to synchrotron radiation (SR) light with photon energy of 800 eV, the same STED phenomenon occurred. The spot size of the luminescence was reduced by the STED phenomenon and this spot size decreased as the STED laser's photon energy increased. The energy dependence of the Ce:LSO luminescence levels can be used to explain the change in the spot size at the luminescence point. [ABSTRACT FROM AUTHOR]

Pyrochlore materials with novel properties are in demand with multifunctional applications such as optoelectronics, scintillator materials, and theranostics. Many reports have already indicated the importance of the synthesis technique for Nd2Zr2O7 (NZO) nanoparticles (NPs); however, no explanation has been provided for the reason behind the nature of its phase selectivity. Here, we have explored the structural and optical properties of the NZO NPs synthesized by a molten salt synthesis method. We have synthesized size-tunable NZO NPs and correlated the particle size with their structural behavior and optical performance. All NZO NPs are stabilized in defect fluorite phase. Neutron diffraction provided insight on the behavior of oxygen in the presence of heavy atoms. We have collected bright amalgam of blue and green emission on UV irradiation due to the presence of oxygen vacancies from these NPs. We have carried out in situ XRD and Raman investigations to observe the temperature-induced phase transformation in a controlled argon environment. Interestingly, we have not observed phase change for the molten salt synthesized fluorite NZO NPs; however, we observed phase transformation from a precursor stage to pyrochlore phase by in situ XRD directly. These observations provide a new strategy to synthesize nanomaterials phase-selectively for a variety of applications in materials science. [ABSTRACT FROM AUTHOR]

A bilateral comparison of C activity measurements between ENEA-INMRI (Italy) and NCBJ RC POLATOM (Poland) was organized in the year 2015 and piloted by POLATOM, which provided the sources for the comparison. A set of six sources in Ultima Gold scintillator was measured at POLATOM using four different counters by two liquid scintillation counting methods: TDCR and CIEMAT/NIST. Three of sources were measured also at ENEA-INMRI by using two different TDCR counters. The results achieved in the comparison show an excellent agreement. [ABSTRACT FROM AUTHOR]

This article is a general overview of the potential capacities of plastic scintillators in radionuclide activity determination. Plastic scintillation (PS) behaves as liquid scintillation does, but with some differences related to the solid state of plastic scintillators. These differences are the base of some drawbacks and some advantages, related to the use of PS. This article describes how these capacities are affected by PS composition, sample preparation, scintillation mechanisms and quenching calibration procedures. It also describes the capabilities for alpha and beta emitter determination and discrimination through the use of PS microspheres and PS resins and their application to different types of samples and radionuclide determination. [ABSTRACT FROM AUTHOR]

X-ray induced luminescence spectra in optical range of wave-lengths (200-700 nm) and thermoluminescence curves for fluoride, fluorosulphate, fluorophosphate and fluorooxalate compounds of the titanium subgroup elements with alkali metals and ammonium have been obtained. Influence of annealing and repeated X-raying on luminescence (XRL) spectra of a number of compounds has been examined. Alloy additives influence on fluorine compounds XRL spectra has been examined. Most of compounds being under study may be used as X-ray luminophores, scintillators and dosimeters. The highest intensity of luminescence was achieved for such compounds as KZrF, CsZrF, RbZrF (especially for doped KZrF), KHfF and CsZr(PO). Radiation drifting to long-wave range for a number of fluorophosphatezirconates in comparison with fluorides may be a positive moment in making luminophores on their base. [ABSTRACT FROM AUTHOR]

Indirect detection is a versatile way to detect hard x-rays. It is based on an x-ray-to-light converter, optical coupling, and a visible light detector. The converter screen, known as a scintillator, is deployed in both imaging and point detection, using either signal integration or counting. Two applications are explored in this review—sample examination and x-ray beam diagnostics for synchrotron sources. A large variety of scintillators are available to fulfill the needs of synchrotron applications. High dynamic range, small pixel size, and radiation hardness are the major advantages of scintillators. This article provides a review of the technical and scientific aspects of scintillators used in synchrotron radiation (i.e., storage rings and x-ray free-electron lasers). The advantages and drawbacks of implementation of the most popular scintillators on synchrotron beamlines are described. [ABSTRACT FROM AUTHOR]

The effect of Ce and Pr ions on spectral-kinetic characteristics of luminescence of lithium-phosphate-borate glasses is studied. It is shown that terbium ion luminescence caused by transitions from D and D multiplets to the ground 7FJ term is detected in samples containing Tb/Ce and Tb/Pr. It has been found that an increase in the concentration of cerium ions from 0.2 to 1 wt % leads to an increase in the intensity of main luminescence bands of terbium ions. In Tb/Pr glasses, a decrease in the relative light yield is observed with an increase in the concentration of Pr ions. Processes of energy transfer between Tb/Ce and Tb/Pr ions are discussed. [ABSTRACT FROM AUTHOR]

By the low-gradient Čzochralski method, both undoped and copper ion activated LiMg(MoO) crystals are grown. The charge state and structural position of impurity copper ions are determined using EPR. Investigations of the luminescence properties reveal that luminescence with a maximum at λ = 520 nm is observed for LiMg(MoO) crystals. A decrease in the temperature increases the intensity of this luminescence. It is found that the doping of LiMg(MoO) crystals with copper ions also increases the luminescence intensity with a maximum at λ = 520 nm. It is supposed that cation vacancies, which provide the charge compensation when copper ions substitute for lithium ions, are responsible for the luminescence. [ABSTRACT FROM AUTHOR]

Results of investigations into the scintillation properties of ZnWO crystals with different prehistory are presented. A model of the processes leading to a dependence of the luminescence intensity on the depth of penetration of exciting radiation into the material is suggested. [ABSTRACT FROM AUTHOR]

The spectra and decay of luminescence in scintillation glass of the LiO-BO-PO-CaF system doped by Gd, Gd/Ce, Gd/Pr, Tb, Tb/Ce, and Tb/Eu have been investigated. The technology of synthesis has been described and the evolution of luminescence spectra relative to the electron excitation pulse has been studied. The presence of the buildup stage in the kinetics of terbium ions luminescence was revealed in the bands at 380 and 490 nm. The existence of interaction between ions (Gd and Ce, Tb and Ce, Tb and Eu) has been established. The estimation of the scintillation efficiency of glass with rare earth ions (REIs) has been performed. [ABSTRACT FROM AUTHOR]

Results of investigating an assembly of thin scintillators and silicon photomultipliers for registering relativistic particles with the minimum ionization are presented. A high efficiency of registering relativistic particles using an Ej-212 plastic scintillator, BSF-91A wavelength-shifting fiber (Saint-Gobain), and a silicon photomultiplier (Hamamtsu) is shown. The measurement results are used for creating a scintillation hodoscope of the magnetic spectrometer for registering γ quanta in the GlueX experiment. [ABSTRACT FROM AUTHOR]

In recent years, the cerium-doped lanthanum bromide, LaBr (Ce = 5 %) detector is increasingly playing an important role in radiation measurements because of its higher energy resolution (~3 % at 662 keV), faster luminescence decay time (~35 ns) and higher detection efficiency compared to 7.65 cm × 7.65 cm NaI(Tl) detector. Intrinsic spectra between 1,800 and 3,000 keV derived from internal radioactivity within LaBr(Ce) scintillators have been investigated in some literatures, and these results are confirmed by the experiments in this work. In this paper, a new method for LaBr(Ce) detector energy calibration from 100 to 2,000 keV is proposed using the intrinsic spectra (self-calibration) instead of the standard gamma sources. Proof-of-concept experiment results show that self-calibration can guarantee energy accuracy of better than 0.815 % and can be applied outside the laboratory. The stability and applicability of this method are also investigated systematically. [ABSTRACT FROM AUTHOR]

One-dimensional LuSiO:Ce (LPS:Ce) luminescent fibers were prepared by the sol-gel process combined with electrospinning with polyvinyl butyral as polymer in this study. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, thermogravimetric and differential scanning calorimetry, Fourier transform infrared spectroscopy, photoluminescence, and kinetic decays were used to characterize the resulting samples. After calcinated at 1200 °C, pure crystalline phase of LuSiO was obtained with well maintenance of the fiber morphology. The excitation and emission curves of LPS:Ce samples are influenced by cerium-doping concentrations. LPS:0.5%Ce fibers show the most intense emission among the samples. A fast decay time of tens of nanosecond was also observed in LPS:Ce fibers. Furthermore, LPS:0.5%Ce powders and Y co-doped LPS:0.5%Ce fibers were also prepared in a similar way for comparison. As a result, LPS:0.5%Ce fibers present a much stronger emission and higher quantum efficiency than that of LPS:0.5%Ce powders, and a close efficiency compared with YLuSiO:0.5%Ce fibers. In addition, a facile and efficient fiber molding process can be realized to assemble one-dimensional LPS:Ce fibers into three-dimensional (3D) fibers structures with different shapes like bracelet and spool. Such 3D fiber structures are dense enough and well-shaped even if after high temperature calcination. The high performance LPS:Ce fibers and LPS:Ce 3D fibers may have great potential applications for luminescent clad sensors, optoelectronic devices, or scintillating detectors [ABSTRACT FROM AUTHOR]

The optical and spectral characteristics of isotopically enriched Czochralski-grown 40Ca 100MoO 4 single crystals have been investigated. This material is promising for detecting double neutrinoless β decay. The possibility and the technique of spectrophotometric monitoring of weak residual absorption near the intrinsic luminescence peak of this scintillation material, which is designed for developing new-generation detectors of elementary particles, are considered. [ABSTRACT FROM AUTHOR]

The crystals of zinc tungstate (ZTO) are a radiation-hardened matrix and are widely used as scintillators for high energy radiation. Therefore, it is interesting to study the possibility of introducing gadolinium ions into this structure to obtain the lasing properties. In order to activate ZTO crystals by gadolinium ions, 0.5 mol.% of GdO is added to the load. High-quality large crystals of ZTO are produced. The spectra of optical transmission, luminescence excitation, and luminescence are measured at room temperature. It is shown that the introduction of gadolinium ions does not result in a shift of the main luminescence band of the ZTO crystals. The analysis of the ESR spectra and their modeling enables the calculation of spin-Hamiltonian parameters. It is shown that the observed spectrum depends on the state of Gd ions with S = 7/2 and is well described by the spin-Hamiltonian parameters g = 1.9835, g = 1.9685, g = 1.9688 and D = 644.88 Gs, E = 161.49 Gs. Directions of the principal values of the D tensor are determined; they reflect a strong distortion of the nearest-neighbor oxygen environment. [ABSTRACT FROM AUTHOR]

Based on the corrected phase diagrams proper growth conditions for Li2Zn2(MoO) crystals are selected. Large crystals (up to 100 mm), both impurity-free and activated by transition metal ions (Cu, Cr), are grown by the low-gradient Czochralski method. By the EPR method the charge state and structural position of copper and chromium ions are determined. The performed studies of luminescent properties show that for impurity-free crystals luminescence with λ = 388 nm with a two-exponential luminescence decay with τ = 2 ns and τ = 6 ns is observed at room temperature. At 77 K for both impurity-free crystals and those activated with transition metal ions luminescence with λ = 560 nm and the luminescence lifetime τ = 100 ns is observed, the intensity of luminescence with λ = 560 nm depending on the nature and concentration of transition metal ions. Cation vacancies responsible for the charge compensation of impurity transition metal ions are assumed to be also responsible for low-temperature luminescence. [ABSTRACT FROM AUTHOR]

The Ce-doped yttrium ortho- and pyrosilicate powders were prepared in a powder form by the formamide-modified sol-gel method. Crystal structure was checked by x-ray diffraction and sample morphology by transmission electron microscopy measurements. Both ortho- and pyrosilicate pure phases were obtained by the previously mentioned preparation procedure and proper annealing temperature was determined to obtain the maximum scintillation efficiency. Luminescence spectra and decays were measured to better evaluate the source of efficiency losses in the scintillator mechanism of samples heat-treated at lower temperatures. The potential of this preparation method for manufacturing the nanocomposite scintillators was discussed. [ABSTRACT FROM AUTHOR]

For traditional applications such as cathode ray tubes and fluorescent lamps, many inorganic phosphors have been optimised during decades. For new applications in display and lighting technology, novel materials are being developed. After giving a short history of sulfide phosphors, the present paper will focus on Ca1− x Sr x S:Eu single crystal particle phosphors. The material is grown by solvothermal synthesis, process not needing toxic gases or high temperature processing steps. This phosphor combines a broad excitation spectrum and a broad—saturated red—emission spectrum, which makes it an ideal material for wavelength conversion in LEDs for general lighting. [ABSTRACT FROM AUTHOR]

A pulsed X-ray source has been designed and constructed with the following parameters: X-ray tube voltage, 10-50 kV; anode current, up to 2 A; pulse duration (smooth control), 80 ns-2 μs; and leading and trailing front width, 6 ns. The source can operate in both single-pulse and pulse-train mode with a repetition frequency of up to 2 kHz. The X-ray pulse has a rectangular shape with a relative amplitude instability below 0.8%. In combination with appropriate detection system, the proposed X-ray source allows the kinetics of X-ray-induced luminescence growth and decay to be measured in a six-decimal-order dynamic range with respect to time and amplitude. Examples of X-ray-induced luminescence kinetics measured in scintillators are presented. [ABSTRACT FROM AUTHOR]

We have studied the effect of lead dopant on the optical absorption, photoluminescence, and x-ray luminescence spectra, and the scintillation characteristics of CdI2 at room temperature. The crystals for the study were grown by the Stockbarger-Bridgman method. Activation of CdI2 from the melt by the compound PbI2 leads to the appearance in the absorption spectra in the near-edge region of an activator band at 395–405 nm, which is interpreted as an A band connected with electronic transitions from the 1S0 state to the 3P1 levels in the Pb2+ ion. For x-ray excitation, CdI2:Pb2+ crystals with optimal dopant concentration (∼1.0 mol%) are characterized by a light yield with maximum in the 570–580 nm region that is an order of magnitude higher than for CdI2 crystals in the 490–500 nm band. For α excitation, the radioluminescence kinetics for cadmium iodide is characterized by a very short (∼0.3 nsec) rise time and fast decay of luminescence, with τ1 ≈ 4 nsec and τ2 = 10–76 nsec. Depending on the conditions under which the crystals were obtained, the fast component fraction is 95%–99%. The crystal is characterized by a similar scintillation pulse in the case of excitation by x-ray pulses. The radioluminescence pulse shape for CdI2:Pb in the decay stage is predominantly exponential, with luminescence decay time constants τ1 ≈ 10 nsec and τ2 = 200–250 nsec. This system is characterized by low afterglow, at the level for the Bi4G3O12 scintillator. We have demonstrated the feasibility of using CdI2:Pb as a scintillator for detecting α particles. [ABSTRACT FROM AUTHOR]

A fundamentally new filtration material has been developed on the basis of original methods for producing porous and fibrous polymeric scintillators. This material combines the ability to filter radioactive contaminations in liquids and gases with the possibility of continuously monitoring the radioactive contamination level. The filtration materials were manufactured by means of the technology of production of nonwoven filtration materials involving the electrostatic spinning method. Our study resulted in the production of ultrathin fibers based on polystyrene with various luminescent additives. The obtained bifunctional filtration materials incorporated in a detector based on an ФЭУ-100 PMT have been tested under laboratory conditions in the realtime mode. The detector’s performance parameters—sensitivity to radon, radiation-response linearity, and radiation stability—have been measured. The activity-decay and luminescence-intensity-decay constants of the exposed samples almost coincide, thereby indicating a high radiation resistance of the material. The filtration material exhibits high sensitivity to the detection of different types of pollution with radioactive preparations, including α-and β-active substances. [ABSTRACT FROM AUTHOR]

The scintillation properties of plastic scintillators based on polymethyl methacrylate with various luminescent dyes are considered. It is shown that replacing the naphthalene conventionally used in these scintillators as a secondary solvent with octadeuteronaphthalene and 1,3-divinylbenzene will not alter either their scintillation efficiency and optical transparency, or their thermal, light, and radiation-damage stability; replacing it with 1,1,3-trimethyl-3-phenylindan, however, improves all these characteristics. It is demonstrated that n-terphenyl, 2,5-diphenyloxazole, 2-biphenyl-5-phenyl-1,3-oxazole, 2-biphenyl-(α-naphthyl)-1,3-oxazole, 2-phenyl-5-(4-biphenylyl)-1,3,4-oxadiazole, and 2-(4′- tret-butylphenyl)-5-(4″-biphenylyl)-1,3,4-oxadiazole can be used as luminescent activators, and n-bis-( o-methylstyryl)-benzene and 1,4-di-(5-phenyl-2-oxazolyl)-benzene are applicable as wavelength shifters. [ABSTRACT FROM AUTHOR]

The results from studies of the scintillation characteristics of new multicomponent composite scintillators are described. These scintillators were developed on the basis of inorganic matrices, a set of heavy inorganic and organic scintillating fillers, and activators based on luminescent additives. The characteristics of some of the produced composite scintillators turned out to be nonadditive with respect to the characteristics of their components. Studies of the scintillation processes in dynamically changing media were resumed. The equations obtained allow the description of the scintillation process for a wide class of multicomponent media in both static and dynamically changing states. [ABSTRACT FROM AUTHOR]

The instrument is designed on the basis of a fast scintillator and a high-speed image-converter tube for hard X and γ rays (≥10 keV). Using a scintillator, it is possible to obtain an almost constant spectral response over an energy range of 40–1000 keV. The time resolution of the camera is governed by the luminescence decay time in the scintillator and may go as high as 100–150 ps. The instrument is used at the ISKRA-5 facility to detect pulses of hard X rays. [ABSTRACT FROM AUTHOR]

The scintillation properties of new composite scintillators based on both organic and inorganic matrices with inorganic scintillating fillers have been investigated. For some of these composite scintillators, their characteristics are not additive with respect to the characteristics of their components. The laws responsible for changes in the scintillation process in dynamically changing media are investigated. [ABSTRACT FROM AUTHOR]

The results of studies of the scintillation and optical characteristics of new hybrid scintillators based on single-component and multicomponent polymer mixtures are presented. Hybrid scintillators using luminescent salts as scintillation dyes are obtained. The appearance of structures in optical transmission spectra and rapid shortening of the scintillation decay times of the hybrid scintillators are observed in certain ranges of the concentrations of the introduced fusible inorganic fillers. The characteristics of the hybrid scintillators turn out to be not additive with respect to the characteristics of the components incorporated into them. [ABSTRACT FROM AUTHOR]

The energy and spatial resolution of a large-volume liquid-scintillator detector has been investigated. The relations have been derived, which allow the energy and spatial resolution of the detector to be estimated without modeling. The calculations involve the light-collection functions of the detector obtained either by the Monte Carlo method or in the measurements taken with radiation sources. The relations are verified with the experimental data of the CTF (Counting Test Facility) detector, which is a prototype of the new Borexino detector for solar neutrinos. An event reconstruction technique using charge and time data from the photomultiplier tubes (PMTs) is analyzed with the help of these relations in order to improve the detector resolution. Algorithms for the energy and coordinate reconstruction of individual events are presented. [ABSTRACT FROM AUTHOR]

Zinc-oxide-based ceramics were prepared by uniaxial hot pressing and their optical properties and luminescence-scintillation characteristics (for X-ray and gamma excitation) have been studied. The ceramics exhibit 35% transmission in the region of maximum wavelength of X-ray-induced luminescence (520 nm); an absolute light yield from 10 900 to 25 360 photons/MeV (depending on the pulse formation time in a spectroscopic amplifier); energy resolution of 11.8–19.2% (for complete absorption of 662-keV gamma quanta); and linear relative yield within 2% in a 35-662 keV energy range. [ABSTRACT FROM AUTHOR]

It is shown that the intensity of luminescence of cadmium tungstate crystals changes nonmonotonically under electron irradiation. At low irradiation doses, an increase in the luminescence intensity can be observed. However, with an increase in the irradiation dose, the luminescence intensity decreases. The effect observed can be explained by the competition of two processes: increase in the number of luminescence centers and nonradiative recombination under the action of irradiation. [ABSTRACT FROM AUTHOR]

A fiber-optic ionizing-radiation detector is composed of a scintillation sensor, an optical fiber, and a photodetector. Due to the miniature size and the high radiation resistance, the detector is capable of measuring the characteristics of powerful neutron and γ-ray fields with a high spatial resolution. A prototype of the detector has been tested using a 60Co γ-ray source with a dose rate as great as 200 R/S. The dynamic range of dose measurements is no less than 105. The detector signal is linearly dependent on the radiation dose rate. The ratio of the useful signal to the background due to radioluminescence of the optical fiber is presented for different types of scintillators. [ABSTRACT FROM AUTHOR]