Inorganic Scintillators Research Articles

Heavy-atom engineering of thermally activated delayed fluorophores for high-performance X-ray imaging scintillators

The architectural design and fabrication of low-cost and reliable organic X-ray imaging scintillators with high light yield, ultralow detection limits and excellent imaging resolution is becoming one of the most attractive research directions for chemists, materials scientists, physicists and engineers due to the devices’ promising scientific and applied technological implications. However, the optimal balance among X-ray absorption capability, exciton utilization efficiency and photoluminescence quantum yield of organic scintillation materials is extremely difficult to achieve because of several competitive non-radiative processes, including intersystem crossing and internal conversion. Here we introduced heavy atoms (Cl, Br and I) into thermally activated delayed fluorescence (TADF) chromophores to significantly increase their X-ray absorption cross-section and maintaining their unique TADF properties and high photoluminescence quantum yield. The X-ray imaging screens fabricated using TADF-Br chromophores exhibited highly improved X-ray sensitivity and imaging resolution compared with the TADF-H counterpart. More importantly, the high X-ray imaging resolution of >18.0 line pairs per millimetre achieved from the TADF-Br screen exceeds most reported organic and conventional inorganic scintillators. This study could help revive research on organic X-ray imaging scintillators and pave the way towards exciting applications for radiology and security screening. Heavy atoms like Cl, Br and I introduced into thermally activated delayed fluorescence chromophores can increase the X-ray absorption cross-section. Light yield of ~20,000 photons MeV–1, detection limit of 45.5 nGy s−1 and imaging resolution of >18.0 line pairs per millimetre is demonstrated.

Neutron/[formula omitted]-ray discrimination based on the property and thickness controls of scintillators using Li glass and LiCAF (Ce) in a [formula omitted]-ray field

Recently, various neutron detectors, such as scintillation detectors, are being developed as alternatives to 3He proportional counters. Here we focus on the thickness and property controls of inorganic scintillators used for thermal neutron detection in intense γ-ray fields without considering pulse shape discrimination (PSD) techniques. GS20TM (a lithium glass) and LiCaAlF6 crystals activated with Ce (LiCAF:Ce) scintillators with thicknesses of 0.5 and 1.0 mm, respectively, have been employed because they have faster decay times than other inorganic scintillators. Pulse signals generated by photomultiplier tubes, to which the scintillators were coupled, were inserted into a digital pulse processing unit with a sampling rate of 1 GHz, and the areas of waveforms were integrated for 360 ns. Neutron/γ-ray detections and discriminations were performed via pulse integrations without using PSD techniques. For GS20TM, the relative energy resolution values of the thermal neutron peaks were 11% and 12% in 0.5 mm and 1.0 mm thicknesses, respectively, and those for LiCAF:Ce were 18% and 36% in 0.5 mm and 1.0 mm thicknesses, respectively. In a 60Co γ-ray field, the neutron detection for GS20TM in a 0.5 mm thickness was possible at dose rates of up to 0.919 Gy/h; however, for LiCAF:Ce, neutron detection was possible at 0.473 Gy/h, and it failed at 0.709 Gy/h. The neutron/γ-ray discrimination of GS20TM was better than that of LiCAF:Ce due to its better energy resolution and higher detection efficiency (6Li content).

A Novel Micro-Dosimetry Technique to Advance Small-Field Radiation Therapy Treatment

<h3>Purpose/Objective(s)</h3> Optical fiber-based scintillating dosimetry is the most recent promising technique in modern radiation therapy owing to the miniature size, high sensitivity, flat energy dependency, etc. Despite several advantages, the major issue of using scintillating dosimeters is the Cerenkov contamination and predominantly requires extra measurement corrections. Therefore, this work highlighted a novel micro-dosimetry technique to ensure Cerenkov-free measurement and quality treatment. <h3>Materials/Methods</h3> A micro-dosimetry technique was proposed based on a novel infrared inorganic scintillator detector (IR-ISD). The detector essentially consists of a micro-scintillating head with a sensitive volume of 1.5 × 10⁻⁶ mm³ integrated with optical fiber. The proposed system was evaluated under the 6/15 MV LINAC beam as well as 320KV- ¹⁹²Ir Brachytherapy (BT) source used in patient treatment. Overall measurements were performed using IBA^TM water tank phantoms by following TRS-398 protocol for radiotherapy and TG43U1 recommendations for BT. Cerenkov measurements were performed for different small fields from 0.5 × 0.5 cm² to 10 × 10cm² under LINAC as well as till 0.25cm distance from the BT source. In addition, several dosimetric parameters such as PDD, beam profiling, field output factor, dose linearity, dose rate linearity, repeatability, and scintillation stability were investigated to verify the device's performance. Finally, a comparative study is shown using Monte-Carlo (MC) simulation, reference dosimeters (microDiamond and film), and data from recent literature. <h3>Results</h3> This study highlighted a complete removal of the Cerenkov effect using a point-like miniatured detector, especially for small-field beam treatment. Measurements demonstrated that IR-ISD has acceptable behavior with dose rate variability (maximum standard deviation ∼ 0.15%) for the dose rate of 20 cGy/s to 1000 cGy/s. An entire linear response (R²=1) was obtained with the dose delivered in the range of 4cGy to 1000 cGy, independently of the field size selected from 4 × 4 cm² to 0.5 × 0.5 cm². Perfect repeatability (0.15 % variation from average) and day-to-day reproducibility (0.25% variation) was observed. PDD profiles present accurate dose distribution with almost identical behavior to the reference dosimeter and simulation results (<1.5% variation). The small field of 0.5 × 0.5 cm² profile (inline & crossline) has been measured to characterize convolution effect and source penumbra. Eventually, in BT, a comparison with MC simulations shows that measurement agrees within 0.65% till 0.25 cm source-to-detector distance. <h3>Conclusion</h3> Unlike recent PSD systems (e.g., exradin W1/W2), the proposed micro-dosimetry system requires no Cerenkov corrections and showed efficient performance for several dosimetric measurements. Therefore, the novel IR-ISD detector could be a quality tool for small-field dose verification (e.g., in SRS, SBRT, IMRT, etc.), intra-beam characterizations, and BT treatment plan.

High-precision measurement of the He6 half-life

The half-life of $^{6}\mathrm{He}$ has been measured using a low-energy radioactive beam implanted in an ${\mathrm{YAlO}}_{3}$ Ce-doped inorganic scintillator and recording decay events in a $4\ensuremath{\pi}$ geometry. Events were time-stamped with a digital data acquisition system enabling a reliable control of dead-time effects and detector gain variations. The result, ${T}_{1/2}=(807.25\ifmmode\pm\else\textpm\fi{}0.{16}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}0.{11}_{\mathrm{sys}}$) ms, provides the most precise value obtained so far and is consistent with the only previous measurement having a precision smaller than 0.1%. This resolves the long-standing discrepancy previously observed between two sets of measurements.

Novel Ultrafast Lu2O3:Yb Ceramics for Future HEP Applications

Inorganic scintillators activated by charge transfer luminescence Yb3+ are considered promising ultrafast material to break the ps timing barrier for future high energy physics applications. Inorganic scintillators in ceramic form are potentially more cost-effective than crystals because of their lower fabrication temperature and no need for aftergrowth mechanical processing. This paper reports an investigation on Lu2O3:Yb and Lu2xY2(1−x)O3:Yb scintillating ceramic samples fabricated by Radiation Monitoring Devices Inc. All samples show X-ray excited luminescence peaked at 370 nm. Ultrafast decay time of 1.1 ns was observed by using a microchannel plate-photomultiplier tube-based test bench at Caltech. Considering its intrinsic high density (9.4 g/cm3), Lu2O3:Yb ceramics are promising for future time of fight application for high energy physics experiments.

Large-Area Laminar TEA2MnI4 Single-Crystal Scintillator for X-ray Imaging with Impressive High Resolution.

Current X-ray imaging scintillators are dominated by inorganic scintillators grown through a high-temperature process. Exploring new types of scintillators with mild growth conditions, high light yields, and eco-friendly chemical compositions is essential and challenging. Herein, the zero-dimensional large-area laminar organic-inorganic hybrid metal halide TEA2MnI4 (TEA = tetraethylammonium) single crystal with dimensions of 50 mm × 60 mm × 0.82 mm is grown via a local-heating solvent evaporation method. Compared with its Cl- and Br-based counterparts, the incorporation of the iodine component enhances the X-ray attenuation ability and significantly accelerates the decay of the photoluminescence of TEA2MnI4. Interestingly, the prepared TEA2MnI4 exhibits a high transmittance of >90% over the range of 515-765 nm and exhibits a high light yield of 26288 photons/MeV, which provides the prerequisite for high-resolution X-ray imaging. The TEA2MnI4 single-crystal scintillator displays an astonishing spatial resolution exceeding 25 line pairs per millimeter, which provides a design concept for a Mn-I-based single crystal for high-performance scintillator applications.

Hadron-Induced Radiation Damage in Fast Heavy Inorganic Scintillators

Fast and heavy inorganic scintillators with suitable radiation tolerance are required to face the challenges presented at future hadron colliders of high energy and intensity. Up to 5 GGy and 5 × 1018 neq/cm2 of one-MeV-equivalent neutron fluence is expected by the forward calorimeter at the Future Hadron Circular Collider. This paper reports the results of an investigation of proton- and neutron-induced radiation damage in various fast and heavy inorganic scintillators, such as LYSO:Ce crystals, LuAG:Ce ceramics, and BaF2 crystals. The experiments were carried out at the Blue Room with 800 MeV proton fluence up to 3.0 × 1015 p/cm2 and at the East Port with one MeV equivalent neutron fluence up to 9.2 × 1015 neq/cm2, respectively, at the Los Alamos Neutron Science Center. Experiments were also carried out at the CERN PS-IRRAD proton facility with 24 GeV proton fluence up to 8.2 × 1015 p/cm2. Research and development will continue to develop LuAG:Ce ceramics and BaF2:Y crystals with improved optical quality, F/T ratio, and radiation hardness.

Facilely Fabricated Bright Lead‐Free Perovskite Cs3Cu2I5 Scintillator Film for High‐Definition X‐Ray Imaging

Scintillator is a critical component to detect high‐energy particles or rays, which is widely used in deep space exploration, security inspection, and nondestructive testing and medical diagnosis, such as X‐ray imaging and computed tomography (CT). However, the wider application of traditional inorganic and organic scintillators is limited by the complex operation process or poor adaptability to changeable environment, and there remains a demand to develop green and stable scintillators with high sensitivity and low detection limit. Herein, the one‐step preparation of lead‐free perovskite Cs3Cu2I5 scintillator film for high‐definition X‐ray imaging by conventional chemical vapor deposition method is reported. Cs3Cu2I5 demonstrates good stability and bright‐blue emission at 445 nm and superhigh photoluminescence quantum yield (85.14%). Importantly, upon X‐ray irradiation, the Cs3Cu2I5 perovskite film exhibits light yield (≈39 251 photons MeV−1) as high as two times of the commercially available Ce:LuAG single‐crystal scintillator (≈22 000 photons MeV−1). Furthermore, the practical demonstration for a bamboo stick and insect specimens illustrates sensitive scintillation response to X‐ray signals with superior linearity and high‐quality images in X‐ray photography and CT. Overall, Cs3Cu2I5 film provides nontoxicity, high radioluminescence intensity, and good stability, it can be regarded as a competitive material for X‐ray imaging.

Back Cover Image

AbstractSensitive and fast detection of neutrons and gamma rays is vital for homeland security, high‐energy physics and proton therapy. However, efficient mixed‐field detection using a single material is highly challenging because fast‐neutron detectors rely on light organic scintillators, and γ‐ray detectors use heavy inorganic scintillators and semiconductors. In the cover, the authors (DOI: 10.1002/inf2.12325) illustrate organic‐inorganic hybrid perovskites that combine light organic cations and heavy inorganic skeletons at a molecular level to achieve unprecedented performance for mixed‐field radiation detection, so as to obtain the time information and energy information of the nuclear reaction process accurately.image

Organic phosphorescent nanoscintillator for low-dose X-ray-induced photodynamic therapy

X-ray-induced photodynamic therapy utilizes penetrating X-rays to activate reactive oxygen species in deep tissues for cancer treatment, which combines the advantages of photodynamic therapy and radiotherapy. Conventional therapy usually requires heavy-metal-containing inorganic scintillators and organic photosensitizers to generate singlet oxygen. Here, we report a more convenient strategy for X-ray-induced photodynamic therapy based on a class of organic phosphorescence nanoscintillators, that act in a dual capacity as scintillators and photosensitizers. The resulting low dose of 0.4 Gy and negligible adverse effects demonstrate the great potential for the treatment of deep tumours. These findings provide an optional route that leverages the optical properties of purely organic scintillators for deep-tissue photodynamic therapy. Furthermore, these organic nanoscintillators offer an opportunity to expand applications in the fields of biomaterials and nanobiotechnology.

Improved light yield and growth of large-volume ultrafast single crystal scintillators Cs2ZnCl4 and Cs3ZnCl5

Due to their reported fast decay times, Cs2ZnCl4 and Cs3ZnCl5 are promising candidates for detection of gamma rays and X-rays in high count rate and fast timing applications. In this work, we show that single crystals with better optical quality than previously demonstrated – and larger in size – can be grown via the vertical Bridgman method. Highly transparent Ø7 mm crystals of undoped Cs2ZnCl4 and Cs3ZnCl5 are grown and measured to have light yields surpassing those previously reported, achieving 1980 ± 100 ph/MeV and 1460 ± 70 ph/MeV at 662 keV – a 55% and 232% improvement, respectively. We observe single-component scintillation decay times for both Cs2ZnCl4 (1.66 ns) and Cs3ZnCl5 (0.82 ns) and radioluminescence emission with maximum intensity at ∼290 nm. Scalability of these materials is also evaluated based on growth of Ø22 mm crystals. Minimal cracking is observed, and the fast decay times are maintained at this size. Coincidence time resolution of 3 × 3 × 5 mm3 and 7 × 7 × 10 mm3 pixels cut from Ø22 mm Cs2ZnCl4 are measured to be 148 ± 1 ps FWHM and 175 ± 1 ps FWHM, respectively. The improved performance and ability to be fabricated in large sizes now place Cs2ZnCl4 and Cs3ZnCl5 on the map as potential contenders for radiation detection applications where BaF2 – the most commonly used ultrafast inorganic scintillator – is typically considered.

Performance of a scintillation imaging system for relative dosimetry in pencil beam scanning proton therapy

The proton spot scanning system requires extensive periodic quality assurance procedures to guarantee the conformality of planned dose distribution to the tumor. Detectors with stable, accurate, and fast data acquisition properties make the quality assurance procedures more efficient. For this purpose, a camera-based scintillation imaging system has been developed. A high scintillation efficiency screen coupled with a high-performance camera improved the dose sensitivity and precision required for the measurements. The dose distribution within the scintillating screen can be analyzed from the captured light distribution image in a relatively straightforward way.In this study, we investigated the performance of a 2D detection system by using a scintillating screen (silver-activated zinc sulfide powder deposited on the surface of a plastic scintillator HND-S2) for dose distribution measurement. The characteristics of the system in terms of response reproducibility, linear dose–response, and beam spot size dependence on proton dose were assessed in a series of proton irradiations. To evaluate the accuracy of lateral dose profiles measured by the ZnS: Ag based scintillating screen, we compared the results with plastic scintillator BC-408 and some commercial quality control devices. Several measurements were conducted with proton energies ranging from 70–235 MeV. We found that the detector showed stable response reproducibility (better than 1.6%) and good dose–response linearity (R2¿0.999). The beam spot size was independent of proton dose when the response of the pixel value was between 10% and 90% of the maximum. The in-air spot size measured by the ZnS: Ag based scintillating screen was found to be slightly smaller than the Lynx detector while the BC-408 showed a slightly bigger spot size. The inter-comparison results for scanned fields showed good agreements. The observed differences in beam profile measurement between the inorganic and organic scintillating screens were mainly due to their optical properties and structures. The developed scintillation imaging system with an effective resolution of 0.12 mm proved to be a reliable device for efficiently performing the quality checks for two-dimensional proton dosimetry.

Reduction of detection limit and quantification uncertainty due to interferent by neural classification with abstention

Many measurements in the physical sciences can be cast as counting experiments, where the number of occurrences of a physical phenomenon informs the prevalence of the phenomenon’s source. Often, detection of the physical phenomenon (termed signal) is difficult to distinguish from naturally occurring phenomena (termed background). In this case, the discrimination of signal events from background can be performed using classifiers, and they may range from simple, threshold-based classifiers to sophisticated neural networks. These classifiers are often trained and validated to obtain optimal accuracy, however we show that the optimal accuracy classifier does not generally coincide with a classifier that provides the lowest detection limit, nor the lowest quantification uncertainty. We present a derivation of the detection limit and quantification uncertainty in the classifier-based counting experiment case. We also present a novel abstention mechanism to minimize the detection limit or quantification uncertainty a posteriori. We illustrate the method on two data sets from the physical sciences, discriminating Ar-37 and Ar-39 radioactive decay from non-radioactive events in a gas proportional counter, and discriminating neutrons from photons in an inorganic scintillator and report results therefrom.

Accelerated radiation transport modeling techniques for pencil beam computed tomography using gamma rays

Monte Carlo radiation transport modeling studies were performed for a compact, and high-resolution gamma-ray computed tomography system designed for imaging irradiated nuclear fuel. The system comprises a 60Co source – chosen for its highly penetrating 1173 keV and 1332 keV gamma rays – a pair of high-aspect-ratio pencil beam collimators, and an inorganic scintillator detector. Two acceleration methods are proposed to rapidly model a transmission type gamma-ray tomography system. The first, a variance reduction technique, is based on performing Monte Carlo simulations with a monodirectionally-biased source, sampled from a characteristic sub-volume of the full source volume. The second acceleration method is based on the deterministic calculations using the Beer–Lambert law and detector response characteristics. Comparison of simulations using acceleration approaches with analog simulations of the fully isotropic, full-volume equivalent, show that the Monte Carlo variance reduction technique gives quantitatively accurate predictions for large collimator aspect ratios while the deterministic calculations are semi-quantitative but converge close to the correct result as the collimator aspect ratio increases. As such, these techniques can be used to reduce the computational cost in generating simulated radiographs and tomographs by several orders of magnitude. Experimental validation efforts are currently underway and will be demonstrated in future work.

Power-efficient high-frequency readout concepts of SiPMs for TOF-PET and HEP

Recent SiPM developments, together with improved readout electronics, opened new doors in time of flight positron emission tomography (TOF-PET) and high energy physics (HEP) research with a focus on prompt photon detection with inorganic scintillators. For instance, the relatively high Cherenkov yield of Bismuth Germanate (BGO) upon 511 keV gamma interaction has triggered a lot of interest, especially for its use in total-body PET scanners due to the relatively low production costs of BGO. However, especially in TOF-PET, the electronic readout for BGO still poses unsolved problems. Lab experiments have shown the benefit of Cherenkov detection, with coincidence time resolutions (CTRs) <200 ps FWHM achieved, but lack system integration due to an unacceptably high power consumption (≫30 mW) of the used amplifiers. Therefore it becomes necessary to investigate different readout concepts of modern analog SiPMs, for which we tested several high-bandwidth amplifiers, commercially available, small in dimension, cheap and with a power consumption ranging from 288 mW to only 17 mW. We found that all tested amplifiers showed similar CTR performance of ∼100 ps FWHM coupling 3×3×3 mm3 LYSO:Ce cubes from EPIC-crystals to S14160-3050HS Hamamatsu SiPMs with 3×3 mm2 active area. The CTR performance with BGO is comparable for all tested amplifiers and the noise contribution to the CTR is found negligible. The results obtained lead to the conclusion that power-efficient SiPM readout solutions can be found, also suitable for Cherenkov light detection with BGO, which opens the door for their implementation in application-specific integrated circuits (ASICs) and systems.

Formamidinium Lead Halide Perovskite Nanocomposite Scintillators.

While there is great demand for effective, affordable radiation detectors in various applications, many commonly used scintillators have major drawbacks. Conventional inorganic scintillators have a fixed emission wavelength and require expensive, high-temperature synthesis; plastic scintillators, while fast, inexpensive, and robust, have low atomic numbers, limiting their X-ray stopping power. Formamidinium lead halide perovskite nanocrystals show promise as scintillators due to their high X-ray attenuation coefficient and bright luminescence. Here, we used a room-temperature, solution-growth method to produce mixed-halide FAPbX (X = Cl, Br) nanocrystals with emission wavelengths that can be varied between 403 and 531 nm via adjustments to the halide ratio. The substitution of bromine for increasing amounts of chlorine resulted in violet emission with faster lifetimes, while larger proportions of bromine resulted in green emission with increased luminescence intensity. By loading FAPbBr nanocrystals into a PVT-based plastic scintillator matrix, we produced 1 mm-thick nanocomposite scintillators, which have brighter luminescence than the PVT-based plastic scintillator alone. While nanocomposites such as these are often opaque due to optical scattering from aggregates of the nanoparticles, we used a surface modification technique to improve transmission through the composites. A composite of FAPbBr nanocrystals encapsulated in inert PMMA produced even stronger luminescence, with intensity 3.8× greater than a comparative FAPbBr/plastic scintillator composite. However, the luminescence decay time of the FAPbBr/PMMA composite was more than 3× slower than that of the FAPbBr/plastic scintillator composite. We also demonstrate the potential of these lead halide perovskite nanocomposite scintillators for low-cost X-ray imaging applications.

Monte Carlo characterization of high atomic number inorganic scintillators for in vivo dosimetry in 192 Ir brachytherapy.

There is increased interest in in vivo dosimetry for 192 Ir brachytherapy (BT) treatments using high atomic number (Z) inorganic scintillators. Their high light output enables construction of small detectors with negligible stem effect and simple readout electronics. Experimental determination of absorbed-dose energy dependence of detectors relative to water is prevalent, but it can be prone to high detector positioning uncertainties and does not allow for decoupling of absorbed-dose energy dependence from other factors affecting detector response. To investigate which measurement conditions and detector properties could affect their absorbed-dose energy dependence in BT in vivodosimetry. We used a general-purpose Monte Carlo (MC) code PENELOPE for the characterization of high-Z inorganic scintillators with the focus on ZnSe ( ) Z. Two other promising media CsI ( ) and Al2 O3 ( ) were included for comparison in selected scenarios. We determined absorbed-dose energy dependence of crystals relative to water under different scatter conditions (calibration phantom 12 × 12 × 30cm3 , characterization phantoms 20 × 20 × 20 cm3 , 30 × 30 × 30 cm3 , 40 × 40 × 40 cm3 , and patient-like elliptic phantom 40 × 30 × 25 cm3 ). To mimic irradiation conditions during prostate treatments, we evaluated whether the presence of pelvic bones and calcifications affect ZnSe response. ZnSe detector design influence was alsoinvestigated. In contrast to low-Z organic and medium-Z inorganic scintillators, ZnSe and CsI media have substantially greater absorbed-dose energy dependence relative to water. The response was phantom-size dependent and changed by 11% between limited- and full-scatter conditions for ZnSe, but not for Al2 O3 . For a given phantom size, a part of the absorbed-dose energy dependence of ZnSe is caused not due to in-phantom scatter but due to source anisotropy. Thus, the absorbed-dose energy dependence of high-Z scintillators is a function of not only the radial distance but also the polar angle. Pelvic bones did not affect ZnSe response, whereas large and intermediate size calcifications reduced it by 9% and 5%, respectively, when placed midway between the source and thedetector. Unlike currently prevalent low- and medium-Z scintillators, high-Z crystals are sensitive to characterization and in vivo measurement conditions. However, good agreement between MC data for ZnSe in the present study and experimental data for ZnSe:O by Jørgensenetal. (2021) suggests that detector signal is proportional to the average absorbed dose to the detector cavity. This enables an easy correction for non-TG43-like scenarios (e.g., patient sizes and calcifications) through MC simulations. Such information should be provided to the clinic by the detector vendors.

Organic–inorganic hybrid perovskite scintillators for mixed field radiation detection

AbstractSensitive and fast detection of neutrons and gamma rays is vital for homeland security, high‐energy physics, and proton therapy. Fast‐neutron detectors rely on light organic scintillators, and γ‐ray detectors use heavy inorganic scintillators and semiconductors. Efficient mixed‐field detection using a single material is highly challenging due to their contradictory requirements. Here we report hybrid perovskites (C8H12N)2Pb(Br1−xClx)4 that combine light organic cations and heavy inorganic skeletons at a molecular level to achieve unprecedented performance for mixed‐field radiation detection. High neutron absorption due to a high density of hydrogen, strong radiative recombination within the highly confined [PbX6]4− layer, and sub‐nanometer distance between absorption sites and radiative centers, enable a light yield of 41 000 photons/MeV, detection pulse width of 2.97 ns and extraordinary linearity response toward both fast neutrons and γ‐rays, outperforming commonly used fast‐neutron scintillators. Neutron energy spectrum, time‐of‐flight based fast‐neutron/γ‐ray discrimination and neutron yield monitoring were all successfully achieved using (C8H12N)2Pb(Br0.95Cl0.05)4 detectors. We further demonstrate the monitoring of reaction kinetics and total power of a nuclear fusion reaction. We envision that molecular hybridized scintillators open a new avenue for mixed‐field radiation detection and imaging.image

Stokes Shift Engineered Mn:CdZnS/ZnS Nanocrystals as Reabsorption‐Free Nanoscintillators in High Loading Polymer Composites

AbstractPlastic scintillators are gaining attention as alternatives to inorganic scintillator crystals owing to their low fabrication cost, customable shape/size, and substantially lighter weight that make them suitable for various radiation detection technologies. These include scintillation panels for national security and industrial monitoring, radiation screens for medical diagnostics, and calorimeters for high energy physics. Because of their low density, plastic scintillators are typically doped with high atomic number (Z) sensitizers that enhance the interaction probability with ionizing radiation and excite molecular emitters. Although effective, such a two‐component design suffers from incomplete sensitization, intrinsically limited efficiency due to multiple radiative steps with non‐unity quantum yield, detrimental phase segregation effects and the fragility of organic emitters to ionizing radiation. In this work, an alternative single‐component scheme is proposed based on high‐Z reabsorption‐free CdZnS/ZnS semiconductor nanocrystals (NCs) doped with manganese embedded in a polyvinyltoluene (PVT) waveguide. Optical‐grade nanocomposites free from optical reabsorption of the scintillation light and with performance comparable to commercial products are obtained through a post‐synthesis resurfacing procedure that maximizes the compatibility between the NCs and PVT and preserves their optical properties upon curing.

Organic-Inorganic Hybrid Cuprous Halide Scintillators for Flexible X-ray Imaging.

Recently, organic-inorganic hybrid scintillators have received more and more attention because of their merits of easy preparation, good stability, and nontoxicity. Considering the high cost of traditional inorganic scintillators, here we describe experimental investigations of a low-cost zero-dimensional scintillator comprising organic-inorganic hybrid cuprous halide and its capabilities for sensitive X-ray detection and flexible X-ray imaging. This scintillator is synthesized using a facile antisolvent diffusion method with large scalability (50 g). The crystal structure shows an unreported plane rhombus cuprous halide core, which also demonstrates outstanding photoluminescence with a high quantum yield (99.5%), excellent radioluminescence with an efficient internal light yield (25 000 photon/MeV), and sensitive X-ray response with a low detection limit (40.4 nGy/s). The organic-inorganic hybrid chemical feature allows the fabrication of a flexible film based on this scintillator for fine-resolution X-ray radiography. These advantages endow our organic-inorganic hybrid scintillator with promising potential in wearable and portable medical devices.