X-ray Scintillation Research Articles

Runaway electron diagnostics using silicon strip detector

We present a proof-of-principle measurement of runaway electrons in a small tokamak using a silicon strip detector. The detector was placed inside the diagnostic port of the tokamak vessel and detected the runaway electron signal directly. The measured signal was compared to the signal provided by other tokamak diagnostics, especially the hard X-ray scintillation detector, which detects secondary photons created by interaction of accelerated electrons with tokamak walls (indirect detection of runaway electrons). The preliminary results show that when not saturated, direct detection with a segmented silicon strip detector provides promising new diagnostic information including spatial and temporal distribution of the runaway electron beam, and the measurement results are in good agreement with hard X-ray measurements with a scintillation detector.

One-Dimensional All-Inorganic K2CuBr3 with Violet Emission as Efficient X-ray Scintillators

Lead halide perovskites have shown great X-ray scintillation properties. One big challenge is to find nontoxic replacements for practical applications. Moreover, the scintillator should contain les...

Polymer Composites Entrapped Ce-Doped LiYF4 Microcrystals for High-Sensitivity X-ray Scintillation and Imaging.

Scintillators are widely used for radiation detection. The ability of converting ionizing radiation into visible photons is critical for application in X-ray security, computed tomography, and nuclear cameras. Conventional scintillators involve a high-temperature preparation and pose challenges for device integration and processability. Here, we report a facile hydrothermal synthesis of Ce-doped LiYF4 microcrystals (MCs) and their polymer composites for high-sensitivity X-ray detection and imaging application. These MC scintillators exhibit strong X-ray radioluminescence (RL) at ultraviolet wavelengths and show a high sensitivity to X-rays. Scintillating bulks based on these MCs display both strong RL and tunable emission across the visible spectrum. Further, these MC scintillators can be readily spun into a uniform film with a suitable MC content for X-ray imaging. Scintillating films can generate a strong X-ray-induced emission and long-term stability under X-ray illumination. Dose dependence of the RL intensity of our scintillating film indicates a high sensitivity to X-rays. Importantly, we exhibit an archetype application of scintillating films as X-ray radiography for a printed circuit board (PCB). Such an archetype can provide a decent spatial resolution as high as 0.54 mm. Our finding manifests MC composites of steady and efficient RL as a promising approach for X-ray radiography application.

Great enhancement of image details with high fidelity in a scintillator imager using an optical coding method

High-resolution lens-coupled indirect X-ray scintillator imagers are required by many imaging applications. However, the severe weakening of image details prevents its further performance improvement. Through our research, this image degradation is attributed to the broadband loss of the high-spatial-frequency information caused by the high refractive index. A technique known as high-spatial-frequency spectrum enhanced reconstruction is thus proposed to retrieve this information. A two-dimensional high-density array is covered on the scintillator’s exit surface and operates as an encoder based on which high-frequency information can be shifted to the low-frequency region to improve the signal-to-noise ratio. The experimental results show that the middle-high-frequency signal intensities can be increased by an order of magnitude or more, up to ∼ 50 times. Therefore, the image details can be effectively enhanced to break through the performance bottleneck of such widely used X-ray imagers for synchrotron radiation facilities or tabletop X-ray tubes.

Development of the ZnO:Ga microrods - epoxy composite as a scintillation screen for ultrafast X-ray detection

In order to satisfy the requirements of ultrafast and hard X-ray detection and imaging in the existing and upcoming experimental facilities for high energy physics, the ZnO:Ga microrods - epoxy (ZnO:Ga-EP) composite were successfully synthesized by the hydrothermal and polymerization method. Under X-ray excitation, the ZnO:Ga-EP composite exhibits a narrow and intense near-band-edge emission located at 390 nm. More importantly, the decay time of the near-band-edge emission can reach up to subnanosecond (<1 ns), which is extremely significant for ultrafast X-ray detection and imaging. In addition, there exist an energy transfer from the epoxy host to the ZnO:Ga microrods in the ZnO:Ga-EP composite. In conclusion, this work indicates the ZnO:Ga-EP composite can be used as a potential ultrafast X-ray scintillation screen for applications in ultrafast and hard X-ray detectors.

All-Inorganic Copper Halide as a Stable and Self-Absorption-Free X-ray Scintillator.

Lead halide perovskites have recently shown great potential as X-ray scintillators; however, the toxicity of the lead element seriously restricts their applications. Herein we report a new lead-free and self-absorption-free scintillator based on Rb2CuCl3 metal halide. The Rb2CuCl3 exhibits a near-unity photoluminescence quantum yield (99.4%) as well as a long photoluminescence lifetime (11.3 μs). Furthermore, Rb2CuCl3 demonstrates an appreciable light yield of 16 600 photons per megaelectronvolt and a large scintillation response with a linear range from 48.6 nGyair s-1 to 15.7 μGyair s-1. Notably, the detection limit is as low as 88.5 nGyair s-1, enabling a reduced radiation dose to the human body when a medical and security check is conducted. In addition, Rb2CuCl3 exhibits good stability against the atmosphere, continuous ultraviolet light, as well as X-ray irradiation. The combination of the decent scintillation performance, low toxicity and good stability suggests the Rb2CuCl3 could be a possible promising X-ray scintillator.

The current status of time-resolved XAS beamline at SLRI and application on in situ experiments

Time-resolved X-ray absorption spectroscopy (TRXAS) beamline (BL2.2) was constructed to utilize a synchrotron radiation produced by a 1.2 T bending magnet from a 1.2 GeV storage ring at the Synchrotron Light Research Institute (SLRI), Thailand. The main optical component of the TRXAS beamline is an energy dispersive monochromator (EDM) which was donated by the University of Bonn, Germany. Using the energy-dispersive scheme with a position-sensitive detector, the beam size at the sample position can be small and have a fast detection speed in the XAS spectrum. At BL2.2, XAS measurement can be performed in the transmission mode using a 1024-pixel position-sensitive detector (PSD) and x-ray scintillator. Currently, the maximum measurable x-ray energy has been extended to 12 keV for the Pt L3-edge EXAS measurement. Due to the advantages of the energy-dispersive setup, this beamline has focused on in-situ XAS experiments. In this review, the researchers summarize the developments of experimental tools to characterize catalysts, Li-ion batteries, and thin film using TRXAS to determine their electronic properties and structure under applied conditions.

Epitaxial growth of Ce-doped (Pb,Gd)3(Al,Ga)5O12 films and their optical and scintillation properties

Abstract Се-doped (Pb,Gd)3(Al,Ga)5O12 single crystalline garnet films were grown using liquid-phase epitaxy from four series of supercooled PbO–B2O3-based melt solutions on Gd3Ga5O12 and Gd3Al2.26Ga2.74O12 single crystal substrates. The optical and scintillation properties of the epitaxial garnet films were studied. The 5d-4f emission of Ce3+ ions within 450–650 nm was observed. The highest pulsed cathodoluminescence yield and scintillation yield values under 133Ba excitation for the Pb0.01Ce0.02Gd2.97Al3.13Ga1.87O12 film were 43,100 photons/MeV and 20,000 photons/MeV, respectively. The pulsed cathodoluminescence decay times of the film were 1.8 (1%), 24 (25%), and 60 ns (74%), and the scintillation decay times were 3.9 (7%) and 43.6 ns (93%). Because of the rapid decay and high light yield, Се-doped (Pb,Gd)3(Al,Ga)5O12 garnet films can be used in X-ray scintillators for different applications, such as homeland security.

X-ray excited CsPb(Cl,Br)3 perovskite quantum dots-glass composite with long-lifetime

CsPbX3 (X = Cl, Br, I) perovskite quantum dots (QDs) have emerged as a kind of brand-new X-ray scintillator with high performance. Herein, following the phase transformation from amorphous to crystalline, CsPb(Cl,Br)3 QDs are in-situ precipitated from a borate glass matrix. It is demonstrated for the first time that the perovskite QDs-glass composite yields radioluminescence (RL), showing X-ray excited RL ∼1/18 to that of commercial Bi4Ge3O12 (BGO) single crystal. The color of RL is adjustable, dependent on the anionic species. Evidently, the high power X-ray induced damage in material is recoverable just by re-heating it at glass transition temperature. This work highlights the partial settlement of tough issues in perovskite QDs as scintillators, such as, physical stability, service lifetime, Pb-toxicity, and production scale.

Preparation and properties for X-ray scintillation screen based on ZnO:In nanorod arrays

X-ray scintillation screens as the core component of X-ray imaging detectors have widespread applications in the medical imaging, security inspection, high energy physics, radiochemistry, and so on. For a long time, the development of X-ray scintillation screen mainly focuses on improving the light yield in order to enhance its detection efficiency. However, a novel tendency has recently emerged for ultrafast time performance of the X-ray imaging detector. The indium doping zinc oxide (ZnO:In) with high radiation hardness, higher light yield(&gt;10000 photons/MeV) and subnanosecond decay time is a promising scintillation material for ultrafast detections. In order to satisfy the requirements of X-ray scintillation screens with ultrafast and high-spatial-resolution in the existing and upcoming high energy physics experiments, the ZnO:In nanorod arrays have been prepared on a 100-nm-thick ZnO-seeded substrate by hydrothermal reaction method and then treated by hydrogen plasma in present work. The results of SEM demonstrate the average diameter and length of the ZnO:In nanorods are about 0.5 and 12 μm, respectively. The XRD shows the ZnO:In nanorods are highly aligned perpendicular to the substrate along &lt;i&gt;c&lt;/i&gt;-axis direction. The X-ray excited luminescence spectra show that two luminescence bands are observed, i.e. an ultraviolet emission peak located at about 395 nm and a visible emission band at 450–750 nm. It is particularly important to point out that hydrogen plasma treatment can enhance the ultraviolet emission of ZnO:In nanorod arrays and suppress its visible emission. The reason is attributed to the formation of shallow donors through hydrogen entering the ZnO and the combination of V&lt;sub&gt;O&lt;/sub&gt; and O&lt;sub&gt;i&lt;/sub&gt;. In addition, the fluorescence decay times of the ultraviolet and visible emissions for the ZnO:In nanorod arrays are subnanosecond and nanosecond, respectively, satisfying the demand of the fast X-ray imaging. The spatial resolution of ZnO:In nanorod arrays has been characterized in X-ray imaging beamline at the Shanghai Synchrotron Radiation Facility. Under excitation of the X-ray beam with the energy of 20 keV, a system spatial resolution of 1.5 μm could be achieved by using an 12 μm thickness ZnO:In nanorod arrays as the scintillation screen, which is exceeded the highest level had ever been reported on ZnO:In nanorod arrays scintillation screen. In conclusion, this present work shows that it is a feasible solution for X-ray detection and imaging with high temporal and spatial resolution by using ZnO:In nanorod arrays as the X-ray scintillation screen.

Stability study of organometal halide perovskite and its enhanced X-ray scintillation from the incorporation of anodic TiO2 nanotubes.

Organometal halide perovskite-based optoelectronic devices are currently a hot research area owing to their unique properties, but widespread commercialization is plagued by their poor long-term stability. So far, the degradation mechanism of organometal halide perovskites is still indistinct due to limited real time systematic study. In this work, we in situ study the crystal evolution of an organometal halide perovskite CH3NH3PbI3, which is prepared on different kinds of framework substrates. Based on the in situ grazing incidence X-ray diffraction and X-ray near absorption edge spectrum, we observe the formation of some 2D networks of [PbI6]4− octahedra intermediates during CH3NH3PbI3 degradation in a moist environment at the early step of the degradation mechanism. We also show that the structural stability of CH3NH3PbI3 deposited anodic TiO2 nanotube substrates is relatively better than that of prepared perovskite on TiO2 nanoparticles in moisture. The confinement of the 3D [PbI6]4− octahedral crystal network probability reduces the ion migration by regular pores of crystalline TiO2 nanotubes, improving the stability of the organometal halide perovskite. Furthermore, the X-ray excited luminescence intensity of CH3NH3PbI3 fabricated on TiO2 nanotubes is boosted 88% compared with that of conventional TiO2 nanoparticle substrates, which demonstrates its potential application in scintillation detectors.

BaWO2F4: a mixed anion X-ray scintillator with excellent photoluminescence quantum efficiency.

A new self-activated X-ray scintillator, BaWO2F4, with an excellent photoluminescence quantum efficiency is reported. Hydrothermally grown single crystals, space group P2/n, exhibit a 3D framework structure containing isolated WO2F4 octahedra. BaWO2F4 exhibits green emission under UV light with a high quantum yield of 53% and scintillates when exposed to X-rays(Cu).

Color-tunable X-ray scintillation based on a series of isotypic lanthanide-organic frameworks.

For the first time, we report intense X-ray scintillation enabled by a series of isotypic lanthanide (Eu and Tb) based metal-organic frameworks, initially showing a very efficient X-ray to visible light luminescence conversion. By systematic adjusting of the molar ratio of Eu3+ and Tb3+ in the same MOF structure as a traditional strategy for color-tuning in lanthanide-based photoluminescent materials, linear multicolor visualization of X-ray radiation from red to green can be facilely achieved, providing a new class of scintillating materials with continuous color tunability that can be customized for desired purposes. Moreover, these lanthanide-organic framework based scintillators exhibit excellent radiation resistance and humidity stability, in comparison with the state of the art and commercially-available X-ray scintillator, CsI:Tl.

Radiation protection parameters of glasses with different yttria additives at different photon energies

Additive yttria in manufacturing glasses yieldsbetter shielding properties which can be used for solar cell covers. Selected ratios of yttria and other oxides have been added to borate-based glasses for the synthesizing via technique of melt quenching. The radiation shielding and structural properties were changed after the addition of yttria in the studied glasses. These glasses were studied using x-ray diffraction and scintillation gamma-ray spectrometer. The glasses have been exposed to photons with 0.662, 1.173 and 1.33 MeV energies that emitted from 137Cs and 60Co radioactive sources and the photon intensities were detected using a 3 × 3 inch NaI(TI) detector. The mass attenuation coefficients (μm), half value layers (HVL), tenth value layer (TVL), the mean free paths (MFP), effective atomic numbers (Zeff) and effective electron densities (ED) values have been measured experimentally. The results are also compared to theoretical values outcomes by using XCOM. The results indicate that the YABB10 glass containing 10 % yttria has the lowest HVL, TVL and MFP values than the other glasses. It indicates that the use of Y2O3 in glass increases the gamma shielding properties which means that these materials have a promising use as a cover layer protection.

Unidirectional growth of pure and composite t-stilbene single crystals for scintillator applications

The virgin and equal weight percent composed (bibenzyl & diphenylacetylene) of t-stilbene single crystals were successfully grown by the solvent evaporation adopted Sankaranarayan-Ramasamy method. The structural parameters were exemplified by the powder X-ray diffractometer, all the crystal samples have to be crystallized on monoclinic crystal system. The characteristic functional groups were illustrated through micro-Raman spectral measurements. The photo emissive properties of the pure and composite crystals have been analyzed through photoluminescence and X-ray excited studies with the excitation of 275 nm. The scintillation characterizations were evolved by X-ray luminescence and scintillation decay time, pulse shape discrimination studies using 137Cs and 252Cf as a radiation sources. The t-stilbene:Bibenzyl composite crystals has the better FOM value than diphenylacetylene composed t-stilbene single crystal.

A perspective on the bright future of metal halide perovskites for X-ray detection

Metal halide perovskites (MHPs) changed the world of solution processed semiconductors, previously dominated by organic semiconductors, toward predominantly inorganic materials with a relatively high electron/hole mobility. A series of devices benefit from their optoelectronic properties, including X-ray detectors. After the introduction of MHP X-ray detectors in 2013, they have achieved significant improvements in the form of single crystals, polycrystalline materials, and pixelated imaging devices. In addition, MHPs in the form of colloidal nanocrystals act as excellent scintillators. We see the bright future of MHPs in energy resolved X-ray detection, either achieved in the single counting mode, or in nanocrystal multilayer stacked devices, acting as a combination of selective X-ray filters and scintillators.

Dynamics of Pulsed X-Ray Radiation of a Plasma Micropinch Discharge

A complex of diagnostic equipment has been created and a measurement procedure has been developed for a multi-channel scintillation X-ray spectrometer with nanosecond time resolution in the energy range of 2–70 keV. The dynamics of the spectral composition of pulsed X-ray plasma of a micropinch discharge has been studied using a “low-inductance vacuum spark” facility. The conducted studies made possible to obtain experimental results of the dynamics of the electron temperature Te of plasma during micropinch discharge and to determine the sequence of formation of hard X-ray radiation.

Light Generation in Lead Halide Perovskite Nanocrystals: LEDs, Color Converters, Lasers, and Other Applications.

Facile solution processing lead halide perovskite nanocrystals (LHP-NCs) exhibit superior properties in light generation, including a wide color gamut, a high flexibility for tuning emissive wavelengths, a great defect tolerance and resulting high quantum yield; and intriguing electric feature of ambipolar transport with moderate and comparable mobility. As a result, LHP-NCs have accomplished great achievements in various light generation applications, including color converters for lighting and display, light-emitting diodes, low threshold lasing, X-ray scintillators, and single photon emitters. Herein, the considerable progress that has been made thus far is reviewed along with the current challenges and future prospects in the light generation applications of LHP-NCs.

Samarium-Activated La2Hf2O7 Nanoparticles as Multifunctional Phosphors.

Recent developments in the field of designing novel nanostructures with various functionalities have pushed the scientific world to design and develop high-quality nanomaterials with multifunctional applications. Here, we propose a new kind of doped metal oxide pyrochlore nanostructure for solid-state phosphor, X-ray scintillator, and optical thermometry. The developed samarium-activated La2Hf2O7 (LHOS) nanoparticles (NPs) emit a narrow and stable red emission with lower color temperature and adequate critical distance under near-UV and X-ray excitations. When the LHOS NPs are exposed to an energetic X-ray beam, the Sm3+ ions situated at the symmetric environment get excited along with those located at the asymmetric environment, which results in a low asymmetry ratio of Sm3+ under radioluminescence compared to photoluminescence. High activation energy and adequate thermal sensitivity of the LHOS NPs highlight their potential as a thermal sensor. Our results indicate that these Sm3+-activated La2Hf2O7 NPs can serve as a multifunctional UV, X-ray, and thermographic phosphor.

Lead-Free Halide Rb2 CuBr3 as Sensitive X-Ray Scintillator.

Scintillators are widely utilized for radiation detections in many fields, such as nondestructive inspection, medical imaging, and space exploration. Lead halide perovskite scintillators have recently received extensive research attention owing to their tunable emission wavelength, low detection limit, and ease of fabrication. However, the low light yields toward X-ray irradiation and the lead toxicity of these perovskites severely restricts their practical application. A novel lead-free halide is presented, namely Rb2 CuBr3 , as a scintillator with exceptionally high light yield. Rb2 CuBr3 exhibits a 1D crystal structure and enjoys strong carrier confinement and near-unity photoluminescence quantum yield (98.6%) in violet emission. The high photoluminescence quantum yield combined with negligible self-absorption from self-trapped exciton emission and strong X-ray absorption capability enables a record high light yield of ≈91056 photons per MeV among perovskite and relative scintillators. Overall, Rb2 CuBr3 provides nontoxicity, high radioluminescence intensity, and good stability, thus laying good foundations for potential application in low-dose radiography.