Highest Scintillation Light Yield Research Articles

High-light-yield and fast-response β-Ga2O3–Al2O3 thick-film scintillators epitaxially grown via chemical vapor deposition

β-gallia (β-Ga2O3) has been investigated for adoption in power semiconductor wafers; however, it is a promising scintillating material for X-ray detection screens. Thus, the research on methods for growing β-gallia crystals has attracted considerable attention. Herein, 15-μm thick Ga2O3–Al2O3 solid solution films with β-gallia structure were synthesized using metal–organic chemical vapor deposition (CVD) at deposition rate of 15 μm h−1. A high scintillation light yield of 5400 photons per 5.5 MeV and a fast decay response of 5.1 ns of the produced films were observed, which were comparable or superior to those of the β-Ga2O3 single crystals and transparent ceramics. CVD method proved advantageous for the rapid synthesis of micrometer-thick Ga2O3-based scintillation screens.

Unveiling The Role of Cu+ Doping in Rb2AgBr3 Scintillators toward Enhanced Photoluminescence Quantum Efficiency and Light Yield

AbstractDoping in luminescent metal halides has become an effective strategy for tailoring the optoelectronic properties. Herein, Cu+ is introduced into Rb2AgBr3 to design the synthesis of Rb2AgBr3:xCu+, which possess cold‐white light emission at room‐temperature without changing the spectral profiles; however, the Cu+ incorporation significantly enhances the photoluminescence quantum efficiency to 98.8% in Rb2AgBr3:0.05Cu+. Additionally, a high scintillation light yield of up to 79 250 photons MeV−1 and a low detection limit of 714.83 nGy s−1 have been achieved via this Cu+ doping engineering. X‐ray imaging with a spatial resolution of up to 5.8 lp mm−1 is further realized using a large scintillator film prepared by mixing polydimethylsiloxane with Cu+ doped Rb2AgBr3 scintillators. This study provides a Cu+ doping design principle for improving both the photoluminescence and scintillation performances of metal halides.

Cross-sensitization of Ce3+ and Tb3+ luminescence in (Gd, Y)3Al2Ga3O12 scintillation ceramics

Crystalline ceramic material (Gd,Y)3Al2Ga3O12 codoped with Ce and Tb (GYAGG: Ce, Tb) was demonstrated to be a high light yield scintillator. The luminescence kinetics was proven to be formed by the combining of the direct Tb3+→Ce3+ and inverse Ce3+→Tb3+ transfer of electronic excitations. This forms a mechanism leading to the increase of the slow component fraction in the scintillation and limits the application of the material, when a fast response is required. However, a high light yield opens an opportunity to utilize the developed material for application in the detectors operating in a current measurement mode and, in long living, as high-flux sources of optical photons under the ionizing radiation of a different type.

Light Inorganic Scintillation Materials for Neutron and Charge Particle Detection

The technological aspects of the light inorganic crystalline compounds suitable to create scintillation materials to detect charged particles and neutrons in a wide energy range have been examined. Among them, Li2CaSiO4:Eu was found to be a prospective candidate to control the valent state of the Rare Earth (RE) and to provide a high intensity of luminescence. It was demonstrated that the material has room for future improvement; however, this requires precise engineering of its composition—an experimental search of compositions or additives that will provide the maximum Eu2+/Eu3+ ratio to achieve a high scintillation light yield. The benefits of light inorganic materials are disclosed through the modeling of the linear density of nonequilibrium carriers along secondary particle tracks created in scintillators utilized for neutron detection. It is shown that oxide matrices have a larger linear density in comparison with halide crystalline compounds under alpha-particles and tritons, whereas light oxides can provide smaller numbers under protons.

Zero-Dimensional Hybrid Cuprous Halide of [BAPMA]Cu2Br5 as a Highly Efficient Light Emitter and an X-Ray Scintillator.

Lead halide perovskites have been explored as a new kind of promising X-ray with wide applications in radiation-associated fields, but low light yield and serious toxicity extremely restrict further applications. To address these issues, we herein demonstrated one new zero-dimensional (0D) organic-inorganic hybrid cuprous halide of [BAPMA]Cu2Br5 (BAPMA = N,N-Bis(3-aminopropyl) methylamine) containing discrete [Cu4Br10]6- tetramers as excellent lead-free scintillators. Upon UV light excitation, [BAPMA]Cu2Br5 displays highly efficient broadband yellowish-green light emission with one dominant peak at 526 nm, a large Stokes shift of 244 nm, and a high photoluminescent quantum yield of 53.40%. Significantly, this broadband light emission can also be excited by higher-energy X-ray as radioluminescence with a high scintillation light yield of 43,744 photons/MeV. The detection limit of 0.074 μGyair/s is also far less than the required value for regular medical diagnostics of 5.5 μGyair/s. The solution-assembled hybrid structure facilely enables the [BAPMA]Cu2Br5-based scintillation screen to display high-performance X-ray imaging with a spatial resolution of 15.79 lp/mm showcasing potential application in X-ray radiography. In brief, combined merits of low toxicity and cost, negligible self-absorption, a low detection limit, considerable light yield, and spatial resolution highlight the excellent scintillation performance of 0D hybrid cuprous halide.

Designing LiTaO3:Ln3+,Eu3+ (Ln = Tb or Pr) perovskite dosimeter with excellent charge carrier storage capacity and stability for anti-counterfeiting and flexible X-ray imaging

Developing X-ray charged dosimeters with excellent charge carrier storage capacity and stability is challenging. Such energy storage dosimeters have fascinating use in developing novel applications, for instance, in radiation detection, advanced multimode anti-counterfeiting, and flexible X-ray imaging of curved objects. Herein, novel LiTaO3:Ln3+,Eu3+ (Ln = Tb or Pr) perovskite dosimeters are reported by combining the vacuum referred binding energy (VRBE) diagram of LiTaO3 and the optimization of dopant’s concentration and compound synthesis condition. Based on the VRBE diagram prediction, charge carrier capturing and de-trapping processes in Eu3+ and/or Ln3+ (Ln = Tb or Pr) doped LiTaO3 will be studied to unravel the role of Eu3+ as a good electron trapping centre and to discover a record storage phosphor. The ratios of the thermoluminescence intensity of the optimized LiTaO3:0.005Tb3+,0.001Eu3+ to that of the state-of-the-art BaFBr(I):Eu2+, Al2O3:C, or NaLuF4:Tb3+ are 5.2, 8.8, or 2.8, respectively. The charge carriers can be stored more than 1000 h in LiTaO3:0.005Tb3+,0.001Eu3+. Proof-of-concept anti-counterfeiting application will be demonstrated by combining the colour-tailorable photoluminescence, afterglow, thermally, or optically stimulated luminescence in LiTaO3:0.005Tb3+,xEu3+ and LiTaO3:0.005Pr3+,0.001Eu3+. Multimode anti-counterfeiting application will be proposed by combining a high absolute X-ray scintillation light yield of 19000 ± 1800 ph/MeV of LiTaO3:0.005Tb3+,0.001Eu3+. Proof-of-concept flexible X-ray imaging application will be demonstrated by using the optimized LiTaO3:0.005Tb3+, 0.001Eu3+ dispersed in a silicone gel film.

Neutron transmission imaging with a portable D-T neutron generator

A portable fast-neutron imaging system is being developed to provide complementary information to field X-ray imaging. Applications include inspection of vehicles and infrastructure for corrosion, measurement of material levels in containers, and inspection of munitions and suspicious packages. While fast-neuron imaging generally provides lower imaging resolution compared to X-rays, fast-neutron interaction cross-sections have a weak dependence on material Z. This enables imaging of low-Z materials inside high-Z materials. Here, we discuss the limitations and current improvements in fast-neuron imaging. Limitations in portable fast-neutron imaging systems include low D-T neutron generator output, low light production in ZnS(Cu) imaging scintillators, low resolution due to scintillator thickness and D-T spot size, and digital-panel darknoise that varies in time and position and that can be 100× larger than the neutron signal. We have made improvements in these areas through development of a segmented high light yield scintillator, panel noise mitigation techniques, and testing of new high-output, small spot size D-T neutron generators. The segmented high light yield fast-neutron scintillator demonstrated 5× increase in light compared to ZnS(Cu). An additional 2× improvement in signal-to-noise was demonstrated with panel-noise mitigation techniques. Our MCNP calculations also show good agreement with neutron imaging results We have demonstrated improvements in fast-neutron imaging through development of a segmented high light yield neutron scintillator, mitigation of digital panel noise, and preliminary testing with new high-output, small spot size D-T neutron generators. We have also demonstrated good results modeling fast-neutron images and scatter effects using MCNP.

Compositionally Disordered Doped with Cerium Crystalline Garnet Type Materials for Brighter and Faster Scintillations

Ce-doped tetracationic garnets (Gd, M)3Al2Ga3O12(M = Y, Lu) form a family of new multipurpose promising scintillation materials. The aim of this work was to evaluate the scintillation yield in the materials of quaternary garnets activated by cerium ions with partial isovalent substitution of the matrix-forming gadolinium ions by yttrium or lutetium ions.Materials were obtained in the form of polycrystalline ceramic samples, and the best results were shown by samples obtained from the raw materials produced by the coprecipitation method. It was found that ceramics obtained from coprecipitated raw materials ensure a uniform distribution of activator ions in the multi-cationic matrices, which enables the high light yield and fast scintillation kinetics of the scintillation. It was demonstrated that the superstoichiometric content of lutetium/gadolinium in the material is an effective method to suppress phosphorescence accompanied scintillation. For ceramics with the composition (Gd, Lu)3Al2Ga3O12 , a scintillation yield of more than 50.000 ph/MeV was achieved. The scintillation kinetics was measured to be close to the kinetics with a decay constant of 50 ns.In terms of the set of the parameters, the developed scintillation materials are close to the recently developed alkali halide materials LaBr3:Ce, GdBr3:Ce. Moreover, they have high mechanical hardness, are characterized by the absence of hygroscopicity, and are better adapted to the manufacture of pixel detectors used in modern devices for medical diagnostics.

First Cherenkov directional detection of sub-MeV solar neutrinos in Borexino

Borexino is a 280t liquid scintillator detector at the Laboratori Nazionali del Gran Sasso (LNGS), Italy. Its main goal is the precision spectroscopy of solar neutrinos down to energies of 0.19 MeV and for this task it features an unprecedented radio-purity and a high scintillation light yield. The solar neutrinos are measured by the elastic scattering off electrons which induce isotropically emitted scintillation photons as well as a sub-dominant number of Cherenkov photons that are detected by photomulitplier tubes. Here we present the first detection of sub-MeV solar neutrinos using their associated Cherenkov photons in a high light yield liquid scintillator detector. In Borexino electrons with E>0.16MeV produce Cherenkov photons, where the ratio of Cherenkov photons from the neutrino scattered electrons is estimated to be < 1% for all PMT hits, so a typical event by event direction reconstruction is not possible. Instead this analysis looks at the integrated signal of the PMT hits of all detected events by correlating the position of each hit PMT relative to the reconstructed position of the event and the well known position of the Sun. In this way it is possible to measure an angular distribution that shows the statistical contribution of Cherenkov photons from the solar neutrino recoil electrons. Using the Geant4-based Borexino Monte Carlo to produce the expected angular distribution for solar neutrinos and background we have measured neutrino events out of 19904 total events for an energy region around the 7Be edge between 0.53 MeV and 0.74 MeV.

Development of an omnidirectional Compton camera using CaF[formula omitted](Eu) scintillators to visualize gamma rays with energy below 250 keV for radioactive environmental monitoring in nuclear medicine facilities

We developed an omnidirectional Compton camera for radioactive environmental monitoring which can visualize gamma rays with energy below 250 keV emitted from various radiopharmaceuticals used in nuclear medicine facilities to prevent occupational radiation exposure. An omnidirectional Compton camera based on high light yield scintillators CsI(Tl) or NaI(Tl) developed in our previous studies is a promising system for environmental radiation monitoring because it has a wide field of view and high sensitivity for sub-MeV gamma rays. However, its sensitivity rapidly decreases below 250 keV because photoelectric effect becomes more dominant than the Compton scattering process due to their large effective atomic numbers (approximately 50). Thus, CaF2(Eu) was adopted, which has both low effective atomic number (approximately 15) and high light yield. Four CaF2(Eu) crystals were arranged symmetrically to achieve a relatively uniform acceptance in all directions. Similarly, the detector rotation technique was adopted to suppress artificial patterns in a reconstructed gamma-ray image because of the small number of crystals. Through experiments in a laboratory and at a nuclear medicine facility, the capability of the camera to visualize gamma rays in energies from 250 keV to 60 keV with reasonable observation time for practical clinical use was confirmed.

A Plastic Scintillator Based on an Efficient Thermally Activated Delayed Fluorescence Emitter 9‐(4‐(4,6‐diphenyl‐1,3,5‐triazin‐2‐yl)‐2‐methylphenyl)‐3,6‐dioctyl‐9H‐carbazole for Pulse Shape Discrimination Measurement

AbstractPulse shape discrimination (PSD)‐capable plastic scintillator is in demand for the detection of high‐energy neutrons in the presence of gamma radiation background. Conventional PSD plastics are based on delayed fluorescent dye via triplet–triplet annihilation of a fluorescent dye additive, which is inefficient to harvest the energy of triplet excitons. In recent years, thermally activated delayed fluorescence (TADF) emitters have gained substantial success in organic light‐emitting diodes due to their efficient utilization of the energy of triplet excitons and thereby achieving theoretical unity internal quantum efficiencies. Herein, a highly efficient TADF dye 9‐(4‐(4,6‐diphenyl‐1,3,5‐triazin‐2‐yl)‐2‐methylphenyl)‐3,6‐dioctyl‐9H‐carbazole is reported for the PSD application. This TADF dye may be loaded up to 30 wt% in polyvinyltoluene matrix and still retains high optical transparency. High scintillation light yield and PSD figures of merit are obtained from the TADF plastic. With the introduction of a secondary dye to further increase the utilization efficiency of the excitation energy, the light yield is increased to 6948 photons MeV−1. The measured alpha/gamma PSD figure of merit is 1.12 at the energy threshold of 100 keVee and neutron/gamma PSD figure of merit is 1.32 at the threshold of 1000 keVee.

Metal Halide Scintillators with Fast and Self‐Absorption‐Free Defect‐Bound Excitonic Radioluminescence for Dynamic X‐Ray Imaging

AbstractScintillators for radiation detection are of great significance in medical imaging, security, and nondestructive inspection. The current challenge for scintillators is to simultaneously achieve high scintillation light yield, fast radioluminescence, simple film fabrication, large X‐ray attenuation efficiency as well as stable and nontoxic compositions; no previous scintillators fulfill all the above requirements. Here, metal halide Rb2AgBr3, possessing defect‐bound excitonic radioluminescence, is shown as efficient and fast scintillators. This nontoxic and stable scintillator emits from excitons bound to neutral bromine vacancies, enjoying an efficient and spin‐allowed fast emission with minimized self‐absorption. Rb2AgBr3 thus has a high light yield (25 600 photons MeV−1), fast scintillation decay time (5.31 ns), and a record value of light yield versus decay time (4821 photons MeV−1 ns−1). The close‐space sublimation method is developed for fast and scalable fabrication of oriented Rb2AgBr3 films. The scintillator film is further integrated with commercial flat‐panel imagers, and the spatial resolution reaches 10.2 line pairs per millimeter at the modulation transfer function of 0.2, doubling the resolution of conventional CsI:Tl flat‐panel detectors. The dynamic X‐ray imaging and its use to real‐time monitoring of bone movement without ghosting effect is also demonstrated.

Characterization of Eu-doped Ba2SiO4, a high light yield scintillator

Photoluminescence and scintillation characteristics of Eu-doped Ba2SiO4 were investigated. A broad emission band due to Eu2+ is observed at 500 nm, and the photoluminescence and radioluminescence decay time constants are about 397 and 515 ns, respectively. From the pulse height distribution of 57Co γ-rays, the light yield of Eu:Ba2SiO4 is ∼48 000 ph MeV−1, which is comparable with those of developed oxide scintillators showing a high light yield. The results demonstrate that Eu-doped Ba2SiO4 is a high-performance scintillator for X- and γ-ray measurements and characterized by excellent scintillation output and afterglow.

Library of Two-Dimensional Hybrid Lead Halide Perovskite Scintillator Crystals

Two-dimensional (2D) hybrid lead halide perovskites are potential candidates for high light yield scintillators as they have small bandgaps between 3 and 4 eV and large exciton-binding energy. Here...

Comparison of Scintillation Light Yield of CWO and BGO Single Crystals for Gamma Ray Detection

Nowadays, radioactive materials are being applied in medical imaging. Because humans cannot observe radiation, radiation detection materials are very important to humans. A scintillator is a material that can change gamma photons to visible photons. Good scintillators should have the following properties: high scintillation light yield, good energy resolution, and high density. In this work, the scintillation light yield property of CWO crystals was studied due to its interesting properties, such as high stopping power and low hygroscopicity. CWO crystals were compared with BGO crystals. From the results, it was found that the BGO crystals showed higher scintillation light yield value at 662 keV energy from 137Cs radioactive source than the CWO crystals, resulting in better energy resolution value. The intrinsic light yield and loss parameters for both crystals are also presented in this work.

Thallium strontium iodide: A high efficiency scintillator for gamma-ray detection

Europium-doped TlSr2I5 (TSI), a new high light yield scintillator for gamma-ray detection, has been grown by the vertical Bridgman method. A 12 mm and 16 mm diameter boules of TSI is grown in a two-zone vertical furnaces. Samples extracted from the grown boule have been characterized for their scintillation properties. Energy resolution of <3% (FWHM) at 662 keV and a gamma-ray light yield of approximately 54,000 Ph/MeV have been obtained. Decay times of 395 ns (89%) and 2.0 μs (11%) have been measured.

Optical and scintillation properties of Pr-doped Y2Si2O7 single crystal

Pr-doped yttrium pyrosilicates Y2Si2O7 (YPS) single crystals were synthesized by the floating zone method. Five samples with different Pr concentration from 0.1% to 2.0% were prepared to study optical and scintillation properties. When we measured photoluminescence (PL), the emission due to the 5d-4f transition of Pr3+ appeared in all the samples at the UV wavelength, and PL decay times were around 4–10 ns. In scintillation properties, all of the samples had the same scintillation emission spectral shape with different intensities, and samples with higher Pr concentration trended to have smaller scintillation decay time than those with lower Pr concentration. Under the 137Cs γ-rays irradiation, the highest scintillation light yield among the present samples was 6600 ph MeV−1 in Pr 1.0% one. In addition, linearity and energy resolution as a function of γ-ray energy were observed in all the samples.

Detection of neutrons in a wide energy range with crystalline Gd3Al2Ga3O12, Lu2SiO5 and LaBr3 doped with Ce scintillators

High light yield scintillation materials on the base of lanthanide ions were demonstrated to be a multipurpose scintillation materials. They are widely used to detect γ–quanta and now become prospective to detect neutrons as well. Neutrons were detected through several distinct low energy γ–quanta peaks, generated by lanthanide nuclei in the materials under neutrons. Among three crystalline scintillators, namely lutetium oxy-orthosilicate, lanthanum bromide and gadolinium–aluminum–gallium garnet, the Gd3Al2Ga3O12:Ce (GAGG) scintillator showed the best performance and sensitivity due to the low internal background radioactivity and good cross section of neutron capture by natural mixture of the matrix host-creating Gd ions. The material fits the requirements for neutron detector properties — high Gd content and high scintillation light yield, stopping power and reasonable energy resolution for γ-quanta. These findings create prospects to construct compact multipurpose detectors for space and other application.

Compact and Effective Detector of the Fast Neutrons on a Base of Ce-doped Gd3Al2Ga3O12 Scintillation Crystal

Gadolinium aluminum gallium garnet Gd3Al2Ga3O12:Ce crystal is demonstrated to be an excellent scintillation material for detection of fast neutrons for the first time. This is achieved because the material, first, has high content of Gd, which absorbs neutrons with following prompt emission of $\gamma $ -quanta, and, second, detects this radiation efficiently thanks to high stopping power and high scintillation light yield. GEANT4 modeling was used to distinguish several characteristic regions in $\gamma $ -quanta pulse height spectra acquired with GAGG:Ce crystal under neutron irradiation, with energies nearly 90 and 190, and 511 keV, which have different relative intensities depending on incident neutrons kinetic energy. This was approved by measurements on Am–Be neutron source. Sensitivity of the material to neutrons from Am–Be source was compared to 6Li-based glass, and found to be superior, depending on signal selectivity.

X-ray scintillation in lead-free double perovskite crystals

Metal halide perovskites have shown great performance for various applications, including solar cells, light emitting diodes, and radiation detectors, but they still suffer from the toxicity of lead and instability. Here we report the use of lanthanide series as trivalent metals to obtain low toxicity and highly stable double perovskites (Cs2NaLnCl6, Ln=Tb or Eu) with high scintillation light yield. The crystals exhibit typical f-f transitions of lanthanide cations, while Cs2NaTbCl6 exhibits strong green photoluminescence, and Cs2NaEuCl6 exhibits red photoluminescence. Under X-ray radiations, the light yield of Cs2NaTbCl6 reaches 46600 photons MeV−1, much higher than that of the commercially used (Lu,Y)2SiO5:Ce3+ crystals (LYSO, 28500 photons MeV−1), and previously reported lead-based perovskites (14000 photons MeV−1). As a new member of lead-free perovskites, lanthanide-based double perovskites open up a new route toward radiation detections and potential medical imaging.