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Metal halide perovskites nanoparticles (PNPs) show promising application in X-ray detection and imaging. However, they exhibit poor stability, especially, the emission peak might be evidently shifted with increasing the PNPs concentration. In this work, the composites of CsPbBr 3 PNPs and BaLuF 5 : 15Gd/15Tb NPs are used to prepare scintillation film for the first time. When fixing the PNPs content in the film, its emission center is not changed after the addition of fluoride NPs. The uniform film containing both BaLuF 5 : 15Gd/15Tb to CsPbBr 3 is prepared. The scintillation intensity of the CsPbBr 3 PNPs is enhanced owing to the radiative energy transfer process from BaLuF 5 : 15Gd/15Tb to CsPbBr 3. Our results provide a novel route to improve the scintillation intensity, which might promote the exploration of new scintillators with high performance. • The composite of CsPbBr 3 and BaLuF 5 : Gd/Tb is used to prepare scintillation film. • The PL profile of CsPbBr 3 is not changed after the addition of fluoride NPs. • The RL intensity of CsPbBr 3 is enhanced owing to the radiative energy transfer. • The RL intensity of mixture is increased by ∼ 2.3 times compared to CsPbBr 3. [ABSTRACT FROM AUTHOR]

The Gd 2 Y (1-x) Dy x Al 2 Ga 3 O 12 phosphors were prepared by the solid state reaction to study in the structure, photon absorption, photo- and radioluminescence properties. The XRD represented a crystalline cubic with Ia 3 ‾ d space group as the main structure of phosphor. The Y atomic sites were fine replaced by Dy in phosphor structure with Dy content (x) in a range of 0.25–1.00. The grain sizes of phosphor samples observed by SEM were in several micrometers. In the absorption spectra, phosphors absorbed the photons with various wavelengths in UV, VIS and NIR region. Both direct Dy3+ excitation and Gd3+→Dy3+ energy transfer caused the strong photoluminescence (PL) of Dy3+ around 481 (4F 9/2 → 6H 15/2) and 582 (4F 9/2 → 6H 13/2) nm. The PL decay times of phosphors were around 0.10–0.74 ms. Phosphors performed the strong response to X-rays in radioluminescence (RL) spectroscopy which composed of the sharp emission of Dy3+ ion, broad emission of Y-related complex and weak emission of defects. Phosphor with 0.25 Dy content owned the highest PL and RL intensity of Dy3+ due to the concentration quenching effect and appropriate lattice constant, while free-Dy phosphor had the highest RL intensity of Y complexes. The Gd 2 Y 0.75 Dy 0.25 Al 2 Ga 3 O 12 phosphors is a promising material for the X-ray detection applications, especially the X-ray imaging screen. • X-ray detection ability from luminescence of Dy3+ ion and Y-complex. • Photoluminescence of Dy3+ surrounded by high-symmetry environment in phosphor. • Luminescence under the Gd3+ → Dy3+ energy transfer. • The influence of lattice constant on luminescence properties. [ABSTRACT FROM AUTHOR]

Pneumothorax can be life-threatening if not diagnosed on time. Most of the research studies for pneumothorax detection in chest X-rays (CXR) images have applied the transfer learning approach. In this study, we have explored the parameter-efficient attention based lightweight convolutional neural network (ALCNN) for pneumothorax detection in CXR images. It has stacked convolutional layers with the attention mechanism to re-calibrate channel-wise feature maps. Furthermore, we have also evaluated three different transfer learning approaches to compare the performance with ALCNN. The ALCNN has obtained the comparable results with 10x fewer parameters in comparison to VGG-19 and ResNet-50 architectures. The ALCNN achieved a 0.73 sensitivity and an area under curve (AUC) of 0.79 on the held-out test set. While pre-trained and fine-tuned, VGG, 19, achieved a sensitivity value of 0.52 and 0.71 and an AUC value of 0.72 and 0.81, respectively. Similarly, pre-trained and fine-tuned ResNet-50 achieved a sensitivity value of 0.69 and 0.74 and an AUC value of 0.77 and 0.80, respectively. In the third transfer learning approach, VGG, 19, and ResNet-50 obtained sensitivity values of 0.65 and 0.69, respectively, while the AUC value of 0.79 for both VGG-19 and ResNet-50. The results obtained in our study show that transfer learning did not have a significant impact on performance for pneumothorax detection in CXR. [Display omitted] • Parameter-efficient ALCNN model is proposed for pneumothorax detection in chest X-rays. • The ALCNN obtained comparable results with ten times less parameters when compared with three transfer learning approaches on two deep architectures. • Obtained results show that the transfer learning approaches did not have a significant effect on the performance for pneumothorax detection. [ABSTRACT FROM AUTHOR]

There is a great demand to develop non-destructive techniques to identify and quantify Special Nuclear Materials (SNM) in homeland security and nuclear safeguards applications. Passive assay could be extremely challenging in some scenarios. Active interrogation technique based on photofission has been identified as one of the promising approaches. In radiation detection system design based on such technique, it is highly desired to have abilities to accurately and efficiently simulate delayed γ-rays emitted from photofission reactions. In this work, simulation results were compared with measurement outcomes to demonstrate the capabilities and limitations of the code MCNPX 2.7.0 in the simulation of delayed γ-rays from photofission of uranium and plutonium samples. First, high-energy delayed γ-rays (E γ ~2.7–4.5 MeV) from photofission of 238 U were simulated and validated against the energy spectra measured in between linac pulses. Second, low-energy delayed γ-ray spectra (E γ ~0.6–2.7 MeV) measured with a list-mode system after irradiation of 239 Pu were used in the validation. [ABSTRACT FROM AUTHOR]

Five SiC Schottky photodiodes for X-ray detection have been electrically characterized at room temperature. One representative diode was also electrically characterized over the temperature range 20°C to 140 °C. The performance at 30 °C of all five X-ray detectors, in both current mode and for photon counting X-ray spectroscopy was investigated. The diodes were fabricated in an array form such that they could be operated as either a 2×2 or 1×3 pixel array. Although the devices showed double barrier heights, high ideality factors and higher than expected leakage current at room temperature (12 nA/cm 2 at an internal electric field of 105 kV/cm), they operated as spectroscopic photon counting soft X-ray detectors uncooled at 30 °C. The measured energy resolution ( FWHM at 17.4 keV, Mo Kα) varied from 1.36 to 1.68 keV among different diodes. [ABSTRACT FROM AUTHOR]

Accurate and reliable energy calibration of spectral x-ray detectors used in medical imaging is essential for avoiding ring artifacts in the reconstructed images (computed tomography) and for performing accurate material basis decomposition. A simple and accurate method for relative calibration of the energy thresholds on a multi-bin spectral x-ray detector is presented. The method obtains the linear relations between all energy thresholds in a channel by scanning the thresholds with respect to each other during x-ray illumination. The method does not rely on a model of the detector's response function and does not require any identifiable features in the x-ray spectrum. Applying the same method, the offset between the thresholds can be determined also without external stimuli by utilizing the electronic noise as a source. The simplicity and accuracy of the method makes it suitable for implementation in clinical multi-bin spectral x-ray imaging systems. [ABSTRACT FROM AUTHOR]

Experimental intrusion-extrusion isotherms of MgCl 2 •21H 2 O solution were recorded at room temperature on pure silica FER-type zeolite (Si-FER). The intrusion occurs at 195 MPa and the phenomenon is completely reversible with a slight hysteresis. The “Si-FER - MgCl 2 aqueous solution” system behaves like a spring. The material was deeply characterized before and after intrusion-extrusion experiments and no significant changes were observed. The unit cell parameters were refined – on the basis of the in situ synchrotron X-ray powder diffraction data - up to 1.47 GPa and then at P amb upon pressure release. The Rietveld refinement of the data collected at 0.28 GPa (280 MPa), a pressure close to the intrusion value, shows that both ions and water molecules present in the MgCl 2 aqueous solution were intruded in the porosities. However, the solvation degree of the intruded ions differs from the initial solution, revealing a partial desolvation of both magnesium and chloride ions. As a whole, the nature and amount of the intruded species correspond to a MgCl 2 •10H 2 O composition. Moreover, at a higher pressure (0.68 GPa), a phase transition from the orthorhombic P mnn to the monoclinic P 2 1 /n s.g. is observed in Si-FER. At 1.47 GPa, the zeolite maintains this monoclinic symmetry, while another phase transition, to the monoclinic P 2 1 s g., is argued from the analysis of the pattern of the sample compressed to 2.6 GPa and then collected upon pressure release to ambient conditions. [ABSTRACT FROM AUTHOR]

This paper develops an integrated navigation method based on the X-ray pulsar navigation (XNAV) system and an autonomous optical navigation system for spacecrafts. The X-ray pulsar navigation is implemented by using the difference between the measured and predicated pulse arrival time, which is calculated by comparing an observed pulse profile with a standard pulse profile. A problem arises from the X-ray signal processing in that the spacecraft’s orbit information, which may be unknown, is required to construct the observed pulse profile. The effect of the spacecraft orbit error on the accuracy of the pulse TOA (time of arrival) difference determination is analyzed. It is specified that the performance of the XNAV system may be degraded in the presence of large orbit error. In order to improve the navigation accuracy, an integrated navigation scheme is presented by fusing the measurement information of a X-ray detector and an ultraviolet optical sensor. The XNAV/optical integrated navigation system is effective to mitigate the effect of the spacecraft orbit error. The superiority of the presented scheme is illustrated through numerical simulations. [ABSTRACT FROM AUTHOR]

Abstract The recent development of silicon diode Low Gain Avalanche Detectors (LGADs) has opened the possibility of enhanced response and faster frame rates for the detection of X-rays produced by next-generation light sources. Preliminary results are presented on the exposure of an LGAD to a series of 500 MHz streams of X-rays with energies between 6 and 16 keV from the SLAC SSRL. X-ray absorption pulses from neighboring beam pulses, separated by 2 nsec, are well resolved. Additional results from a novel, AC-coupled LGAD, excited by a narrow infrared laser beam, indicate a point-spread function with a full width of approximately 400 μ m. Further optimization of the AC-LGAD design should allow the extent of the point-spread function to be further reduced, and a granularity of 100 × 100 μ m 2 or finer to be reached. [ABSTRACT FROM AUTHOR]

AgI incorporated perovskite X-ray detectors were fabricated based on the spray-coating technique. The effect of AgI incorporation on the optoelectronic properties was systematically investigated. With suitable amount of AgI content, metal halide perovskite exhibited improved crystallinity, charge carrier mobility, lifetime, and X-ray sensitivity. [Display omitted] • Perovskite thick films were fabricated via spray-coating process. • The effect of AgI incorporation was carefully evaluated and optimized. • X-ray detectors based on the spray-coated perovskite thick junctions were fabricated. • High X-ray sensitivity, low detection limit and fast response were achieved. Metal halide perovskites have emerged as a promising candidate for ionizing radiation detection, thanks to the facile fabrication, excellent optoelectronic properties and high attenuation coefficient. In order to fully absorb the incident X-ray photons, X-ray detectors require relatively thick active layers. However, it is challenging to obtain thick perovskite films based on conventional solution-based techniques, due to the limited solubility and viscosity of the perovskite precursors. In this work, we introduced spray-coating to deposit perovskite films on various substrates, and achieved tunable and thick films. On the other hand, the charge transport is another issue limiting the device performance of perovskite X-ray detectors. Compared with conventional inorganic semiconductors, hybrid perovskites possess relatively poor charge carrier mobility and lifetime. To address this issue, we incorporate AgI within the perovskite precursor, and systematically investigated their optoelectronic properties. It was found that the optimized AgI incorporated perovskite films exhibited the highest mobility-lifetime product, resulted X-ray sensitivity up to 3433 μGy air −1 cm−2 and ultra-low detection limit of 3.5 nGy air s−1, suggesting great potential for X-ray detection. [ABSTRACT FROM AUTHOR]

Although biopsy-based necrosis rate is a golden standard for reflecting the sensitivity of bone tumor and guiding postoperative chemotherapy, it requires biopsy which is invasive and time-consuming. In this paper, we develop a new necrosis rate detection method using time series X-ray images instead of biopsy. To overcome the limitations of few-shot samples, the proposed method utilizes a Generative Adversarial Network with Long Short-term Memory to generate time series X-ray images. For further data expansion, an image-to-image translation network is applied for producing the initial images. These augmented data are treated as the training set of a 3D-Convolutional Neural Network classification model. Our method expands the few-shot bone tumor X-rays by 10 times, and approaches the necrotic rate classification result of biopsy, which is the state-of-the-art technique in the detection of few-shot bone tumor necrosis rate. Furthermore, it provides an efficient method to investigate the bone tumor necrosis rate in few-shot samples. • A deep learning method is proposed to detect necrosis rate with few-shot X-rays. • The Conv-LSTM-GAN network in our method is designed to generate bone tumor images. • Our method expands bone tumor images by 10 times and achieves biopsy-like results. [ABSTRACT FROM AUTHOR]

Developing efficient strategies to fabricate planar photoluminescence scintillators is of great importance to explore X-ray detectors with new platform. Rare-earth (RE) doped Lu 2 O 3 thin films are successfully fabricated by mild aqueous phase electrochemical deposition on ITO/glass substrates with low-temperature post-annealing treatment. The as-prepared Lu 2 O 3 :RE3+ (RE = Eu, Tb and Tm) thin films exhibit steerable thickness, high transparency in the visible-NIR range, and low transmittance at UV band mainly due to the oxygen-metal (O2--RE3+) charge transfer processes and the 4f-4f transitions of the RE3+. The Lu 2 O 3 :RE3+ thin films emit intense red, green and blue (RGB) photoluminescence, which mainly correspond to the 5D 0 -7F 2 transition of Eu3+, 5D 4 -7F 5 transition of Tb3+ and 1G 4 -3H 6 transition of Tm3+ respectively. Moreover, the transparent Lu 2 O 3 :RE3+ thin films also exhibit high sensitivity and linearity luminescence to the X-ray stimulation in a dose rate from 30 to 160 mGy s−1. This rapid and energy-saving synthesis show high efficiency to fabricate rare-earth doped thin-film with a tunable optical performance for optoelectrical application in the fields of solar light concentrators, agricultural light conversion thin films, biosensors, photodetectors and especially the X-ray detectors. [Display omitted] • The thickness of Lu 2 O 3 :RE3+ (RE = Eu, Tb and Tm) films prepared by electrodeposition is controllable. • The thin films exhibit high transparency at Visible-NIR band. • The Lu 2 O 3 :RE3+ thin films emit intense RGB photoluminescence upon UV light excitation. • The Lu 2 O 3 :RE3+ thin films exhibit high sensitivity and linearity to the X-ray. [ABSTRACT FROM AUTHOR]

Recently, semiconductive polymeric materials have attracted attention as an active layer for detecting ionizing radiation because of their excellent properties such as flexibility, easy production, solution processability and low-cost production. This paper presents X-ray detection properties of Poly(3-hexylthiophene) (P3HT):Phenyl C61 butyric acid methyl ester (PCBM) blend structure with different PCBM loading ratios. P3HT:PCBM mixing ratio was changed from 1:0 to 1:2. Top contact of the pure and blend structured device were produced by using a solution based graphite ink. Devices were constructed with vertical bulk resistive architecture within an ohmic electrode structure as ITO/PEDOT:PSS/P3HT:PCBM/Graphite configuration. Graphite electrode was coated on the active layer with the spray coating method. All devices exhibited ohmic current-voltage (I–V) characteristics. The blend structured devices exhibited stable saw-tooth type behaviour in photocurrent responses against the on and off states of X-rays. Saw-tooth type responses could be evaluated as major evidence for a potential usage of organic electronic device technology direct radiation detectors. Although the best sensitivity value to X-ray was obtained with the blend structure with equal ratio, it was observed that the rise and decay times were shortened with the increase in the amount of PCBM in the blend structure from. [Display omitted] • P3HT:PCBM active layer based X Ray detectors. • Spray coated graphite electrode was used as the top ohmic contact for all devices. • P3HT:PCBM ratio was changed as (1:0), (1:0.5), (1:1), (1:2). • Best sensitivity value to X-ray was obtained with the blend structure with equal ratio of PCBM and P3HT (1:1). [ABSTRACT FROM AUTHOR]

The aims of this study is to improve the sensitivity of indirect X-ray detectors by investigating the properties and application of ternary-blended organic active layers. The ternary-blended active layers studied were composed of conjugated polymer PBDB-T-2F as the donor (D1), non-fullerene Y6 as the first acceptor (A1) and ITIC-4F as the second acceptor (A2). The structural similarity between the two acceptors allows the advantage formation of a homogeneous acceptor phase and results in good film morphology. Another advantage of our approach is the electrical and optical characteristics of the active layer can be modulated based on the mixing ratio of the two acceptors. To find the optimal ternary blending, the content of D1 was fixed while the A1:A2 content ratio was adjusted. The CsI (Tl) scintillator-coupled detector with an active layer of PBDB-T-2F:Y6:ITIC-4F = 1.0:0.6:0.4 achieved the highest sensitivity of 4.27 × 103 μC∙Gy air −1∙cm−2 giving respective improvements of 27.10% and 43.92% compared to binary-blend PBDB-T-2F:Y6 = 1:1 and PBDB-T-2F:ITIC-4F = 1:1. Next, the active layer's spin-coating conditions and the bias conditions were examined to further improve the sensitivity of the detector. Finally, the detector with a PBDB-T-2F:Y6:ITIC-4F = 1.0:0.6:0.4 active layer was shown to have the highest sensitivity of 5.42 × 103 μC∙Gy air −1 cm−2 at a bias of – 1.6 V with a 97 ± 2 nm thick active layer. The aims of this study are to improve the sensitivity of indirect X-ray detectors by investigating the properties of ternary-blended organic active layers. The structural similarity between the two acceptors allows the advantage formation of a homogeneous acceptor phase and results in good film morphology. Another advantage of our approach is the electrical and optical characteristics of the active layer can be modulated based on the mixing ratio of the two acceptors. The CsI (Tl) scintillator-coupled detector with ternary-blended active layer giving respective improvements of 27.10% and 43.92% compared to binary-blended active layer. [Display omitted] • To improve the sensitivity of the X-ray detector, a ternary-blend strategy was applied to the organic active layer. • The X-ray detector using ternary-blended active layer shown 27.10% and 43.92% higher sensitivity compared to their respective binary combinations (PBDB-T-2F:Y6 and PBDB-T-2F:ITIC-4F). • The indirect-type X-ray detector using PBDB-T-2F:Y6:ITIC-4F = 1.0:0.6:0.4 ternary-blended active layer was achieved a high sensitivity of 5.42 × 103 μC∙Gy air −1∙cm−2. [ABSTRACT FROM AUTHOR]

Semiconductor-based direct conversion X-ray sensors have widespread applications spanning from medical diagnosis to industrial inspection. However, current findings on X-ray detection based on perovskites shows high sensitivity but exhibit large leakage current and poor stability, thus, inhibiting them from commercialization. Highly stable AgBiS 2 with large attenuation coefficient (μ = 3.07 g cm−2 at 70 keV), shows excellent charge conversion due to its higher atomic number (Bi, Z = 83), and density (ρ = 7.02 g cm−3) was used for X-ray detection. Here, we approach to enhance the net sensitivity of AgBiS 2 by tailoring all three parameters by segregating micro/ nanocrystals of cerium oxide (CeO 2) at the AgBiS 2 grain boundary (GB) region. From the X-ray impinged photocurrent response, substantial GB segregation of n-CeO 2 at the AgBiS 2 interface leads to improved attenuation and promotes the conversion of multiple scattered X-ray photons into electrons by interacting with the adjacent grains, thus resulting in enhanced photocurrent generation. The sensitivity (S) and noise equivalent dose (NED) ratio were calculated to determine the lowest detectivity of the sensor with less generated noise signals. From these experimental findings, 10 % of n-CeO 2 segregation leads to an improvement in the sensitivity of AgBiS 2 to 29 μC mGy−1 cm−3. [Display omitted] • X-ray sensors were fabricated with micro/ nano CeO 2 segregated AgBiS 2 thick films. • Multiple scattered X-ray photons at the AgBiS 2 grain boundary region were effectively utilized by nano CeO 2 grains, resulting in higher charge carrier generation. • X-ray impinged photocurrent measurement revealed nano CeO 2 :AgBiS 2 presents record sensitivity 29.3 μC mGy−1 cm−3 for 7.97 mGy dose. [ABSTRACT FROM AUTHOR]

Lead-free double perovskite has become a candidate material for green optoelectronic applications due to its low toxicity and human-friendly characteristics. Double perovskite has a huge application prospect in the field of optical detectors, especially X-ray detection in recent years. By introducing propylammonium (PA), we have grown a larger size 2D double perovskite (PA) 4 AgBiBr 8 single crystal. While inheriting the high stability of the 2D material, it also exhibits good X-ray response. The constructed planar Au/(PA) 4 AgBiBr 8 /Au X-ray detector displays a sensitivity of 6.89 μC Gy−1 cm−2 under 40 V bias voltage and 40 keV X-ray radiation. • Preparation of (PA) 4 AgBiBr 8 2D double perovskite single crystals using solution growth. • As-grown (PA) 4 AgBiBr 8 single crystals exhibited suitable optical properties and thermal stability. • The (PA) 4 AgBiBr 8 crystals have a sensitivity of 6.89 μC Gy−1 cm−2 under X-ray irradiation at 40 V bias. [ABSTRACT FROM AUTHOR]

Organometal halide perovskites have proven to be potential materials for X-ray detection due to their great photoelectric properties, high radiation attenuation and low-cost preparation. However, ion migration is one of the obstacles for its applications, especially, ion migration via surface is much easier in single crystal materials than bulk diffusion which could significantly degrade the device performances. In this paper, the KCl passivation layer is prepared by the thermal evaporation method and inserted between crystal and electrode The trap density and μ τ product of pristine and KCl passivated MAPbI 3 devices are compared, and the results demonstrate KCl as a passivation layer can effectively passivate the surface traps and improve electrical performance. The KCl passivated MAPbI 3 detector exhibits a high X-ray sensitivity of 3700 μ C Gy air − 1 cm −2 under −20 V bias. [ABSTRACT FROM AUTHOR]

The K 2 O–Gd 2 O 3 –B 2 O 3 –P 2 O 5 glass doped with Dy 2 O 3 (Dy:KGPB) were synthesized by the melt-quenching technique. These glasses were subjected to characterize the physical, structure, optical and luminescence properties. It was observed that the density, molar volume and refractive index of glass increased with increasing Dy 2 O 3 concentration. The FTIR result confirmed the main glass network of B O B and P O P linkages those were degraded by adding Dy 2 O 3 modifier. Glasses absorbed photons in ultraviolet, visible light and near-infrared region. The photoluminescence under direct Dy3+ excitation performed the strong emissions at 574 and 482 nm corresponding to 4F 9/2 → 6H 13/2 and 4F 9/2 → 6H 15/2 transition, respectively. The Gd3+ excitation also caused strong emission of Dy3+ by the Gd3+-Dy3+energy transfer. Glass doped with 1.00 mol% of Dy 2 O 3 owned the highest emission intensity due to the concentration quenching. The lifetime of 4F 9/2 level was found to decrease with addition of Dy 2 O 3 content via dipole-diploe interaction between Dy3+ ion. Judd-Ofelt (J-O) intensity parameters were initially calculated and applied to evaluate the radiative parameters such as branching ratios, radiative transition probabilities, and stimulated emission cross-sections. The radioluminescence of glass was also investigated and found the scintillation efficiency around 15.6%, compared to BGO scintillator. The Dy:KGPB glass has an interesting potential for solid-state laser, LED and X-ray detection applications. • The energy transfer phenomenon was observed from Gd3+-Dy3+ ions. • The bright greenish-yellow emission was observed for present glasses. • Energy transfer parameter show increasing trend with increase in Dy3+ ions. • X-rays scintillation efficiency of glass was 15.6% compared to BGO scintillator. • CIE chromaticity diagram show greenish-yellow emission under UV lamp excitation. [ABSTRACT FROM AUTHOR]

Bismuth-triiodide has received remarkable attention because of its properties like low toxicity, wide band gap, high density, high attenuation coefficient, and defect tolerance for direct X-ray detection applications. The material has demonstrated promising X-ray detection results in polycrystalline films and single-crystal detectors. However, the inherent defects and voids in the structure of BiI 3 create recombination centers and decrease the charge collection in the detector. Over the last few years, BiI 3 -polymer composites and BiI 3 -based perovskites have been investigated for the defect tolerance to deliver high sensitivity, high SNR, and low detection limit. These composites and perovskites tailor the trap density in the BiI 3 and increase the density of shallow defects, which helps to improve the charge collection. In this review, we summarize the properties and limitations of BiI 3 and the role of deep and shallow defects in charge carriers' transportation. The highlights of the recent developments in BiI 3 -based composites and perovskites to address these challenges to yield high material performance for direct X-ray detection applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Single crystal of Tm-doped LaCl 3 (LaCl 3 :Tm3+) with the dimension of diameter 7 mm and length 55 mm was successfully grown using an in-house-developed Bridgman furnace. The grown crystal has the self-trapped exciton (STE) emission in the range of 300–500 nm along with the characteristic emissions corresponding to the 4f-4f transition of Tm3+ ions under X-ray excitation. The scintillation characterizations of the grown crystal were performed by pulse height spectra, scintillation decay time, as well as pulse shape discrimination studies under γ-ray and α-particle excitation sources. The LaCl 3 :Tm3+ crystal was found to have a high light yield (42,000 ± 4,200 ph/MeV) with 4.2% energy resolution under γ-rays excitation. Moreover, the pulse shape discrimination was studied using 137Cs and 241Am as the radiation sources with a good FOM value. The results conclude the LaCl 3 :Tm3+ single crystal to be a promising candidate for X-ray and γ-ray detection purposes. • The LaCl 3 :Tm3+ crystal was successfully grown by Bridgman technique. • Host STE band and characteristic Tm3+ transition are visible in the XIL studies. • High light yield (41,511 ± 2,906 ph/MeV) with 4.23% energy resolution (137Cs source). • The timing performance of crystal was found to be 3.42 μs (89%) with 137Cs source. • The excellent PSD capability of LaCl 3 :Tm3+ crystal between γ-ray and α-particles. [ABSTRACT FROM AUTHOR]

COVID-19 quickly became a global pandemic after only four months of its first detection. It is crucial to detect this disease as soon as possible to decrease its spread. The use of chest X-ray (CXR) images became an effective screening strategy, complementary to the reverse transcription-polymerase chain reaction (RT-PCR). Convolutional neural networks (CNNs) are often used for automatic image classification and they can be very useful in CXR diagnostics. In this paper, 21 different CNN architectures are tested and compared in the task of identifying COVID-19 in CXR images. They were applied to the COVIDx8B dataset, a large COVID-19 dataset with 16,352 CXR images coming from patients of at least 51 countries. Ensembles of CNNs were also employed and they showed better efficacy than individual instances. The best individual CNN instance results were achieved by DenseNet169, with an accuracy of 98.15% and an F1 score of 98.12%. These were further increased to 99.25% and 99.24%, respectively, through an ensemble with five instances of DenseNet169. These results are higher than those obtained in recent works using the same dataset. • This paper compares 21 CNN architectures for COVID-19 detection in CXR images. • DenseNet169 achieved an accuracy of 98.15% and an F1 score of 98.12%. • An ensemble of DenseNet169 instances increased the F1 score to 99.24%. • The training was repeated five times for each model to get more reliable results. [ABSTRACT FROM AUTHOR]

Here, we successfully prepared Tb3+-activated borogermanate glass by the traditional melt-quenching method. The optical and scintillating properties were investigated by using photoluminescence, transmission spectra, luminescence decay curves and X-ray excited luminescence. High content of Gd 2 O 3 was added into borogermanate glass to improve the density of glass (about 5.52 g/cm3), and thus to enhance the radiation stopping power. Al powder was introduced into the composition as reducing agent. Due to incorporation of Al powder, the internal quantum efficiency of glass increases from 18.8% to 56.3%. Meanwhile, the integrated intensity of X-ray excited luminescence of glass promotes from 29.8% to 46.6% compared to Bi 4 Ge 3 O 12 scintillating crystal. All above results declare that Al powder as reducing agent can strengthen the optical and scintillating properties of Tb3+-activated borogermanate glass. • The density of borogermanate glass with high content of Gd 2 O 3 is 5.52 g/cm3. • The quantum efficiency increases from 18.8% to 56.3% after addition of Al powder. • The XEL intensity promotes from 29.8% to 46.6% due to addition of Al powder. [ABSTRACT FROM AUTHOR]

The glass formula of 20Li 2 O+10AlF 3 +2.5CaF 2 +(66.5- x)P 2 O 5 + x Gd 2 O 3 +1Eu 2 O 3 (PLACEu 1 Gd x), where x = 2,4,6,8,10 mol% have been prepared by conventional melt-quenching technique. These glasses' optical absorption, photoluminescence, decay time, and radioluminescence have been measured at room temperature. Judd-Ofelt's (J-O) analysis of PLACEu 1 Gd 8 has been investigated and the magnitude of parameters follows the trend as Ω 2 >Ω 4 >Ω 6. The important laser parameters such as radiative properties are calculated using J-O parameters and luminescence spectra. The decay time with the transition from the 5D 0 level was estimated under 274 nm and 394 nm excitation using bi-exponential fitting. CIE coordinates, CCT and intensity ratio have been calculated for glass samples. The integral scintillation efficiency of PLACEu 1 Gd 8 is 31% compared with BGO crystal. The PLACEu 1 Gd x glasses are promising for laser medium and x-rays detection material applications. • The effect of Gd 2 O 3 in Li 2 O–AlF 3 –CaF 2 –P 2 O 5 –Eu 2 O 3 glasses was investigated. • The phonon energy was approximate to be 1170.36 cm−1. • The quantum efficiency of PLACEu 1 Gd 8 glass is 97%. • The light yield of the prepared glass was estimated to be 31% of the commercial BGO crystal. • The calculation of CIE, CCT and intensity ratio of these glasses were shown reddish-orange emission. [ABSTRACT FROM AUTHOR]

To improve the characterization of the detection efficiency of a NaI(Tl) scintillation detector in the low energy range, measurements and Monte Carlo simulations were performed with a certified reference material (CRM) and disk sources. The detection efficiency as modeled. In the MCNP simulation, the detection efficiency dropped as expected at 33.17 keV. The X-ray escape correction factors of a 204Tl disk source and MCNP simulations were compared, a factor of the 204Tl was similar. Moreover, Correcting the X-ray escape and using fewer sources than the CRM resulted in better detection efficiency for the NaI(Tl) detector in the low energy range. • An iodine X-ray escape correction factors were calculated using MCNP simulation of a NaI(Tl) scintillation detector. • The summing or overlapped peaks of spectra of disk sources and certified reference material were analyzed. • The iodine X-ray esecape of the detection efficiency in a low energy range was corrected. [ABSTRACT FROM AUTHOR]

Object detection algorithms based on deep learning have been widely used in the intelligent detection of prohibited items in X-ray images during the security inspection process. However, security inspection is a process that emphasizes timeliness, and the low inference efficiency brought by overly complex deep neural networks is not allowed. In this paper, we propose a lightweight object detection framework based on the YOLOv4 algorithm, named LightRay. Where MobileNetV3 is applied as the feature extraction backbone. To effectively deal with the detection problem of prohibited items with small sizes in complex backgrounds, a feature enhancement network in shallow layers is proposed. Where, the Lightweight Feature Pyramid Network (LFPN) and the Convolutional Block Attention Module (CBAM) effectively achieve feature fusion of different scales, while strengthening the features of small objects. The experimental results show that the mAP of the lightRay model is 87.28% on the SIXray data set, while the FLOPs of the model are reduced to the original 1/5, and Params is reduced to 1/3 of the original. In addition, some ablation experiments confirm the ability of the LightRay model the detection of prohibited items with small sizes. The codes of LightRay are released at https://github.com/zhg-SZPT/LightRay. [ABSTRACT FROM AUTHOR]

This paper reports the latest technological development on the Low Gain Avalanche Detector (LGAD) and introduces a new architecture of these detectors called inverse-LGAD (iLGAD). Both approaches are based on the standard Avalanche Photo Diodes (APD) concept, commonly used in optical and X-ray detection applications, including an internal multiplication of the charge generated by radiation. The multiplication is inherent to the basic n ++ –p + –p structure, where the doping profile of the p + layer is optimized to achieve high field and high impact ionization at the junction. The LGAD structures are optimized for applications such as tracking or timing detectors for high energy physics experiments or medical applications where time resolution lower than 30 ps is required. Detailed TCAD device simulations together with the electrical and charge collection measurements are presented through this work. [ABSTRACT FROM AUTHOR]

We have investigated a hard X-ray detector system using a combination of a plastic scintillator and multi-pixel photon counters (MPPC). Photomultiplier tubes (PMTs) have typically been adopted to read scintillators because of their high gain and large photoelectric surface, and studies on PMT and scintillator systems are well advanced. However, PMTs have limitations; for example, they are relatively large in size, require high voltage to operate, and cannot be used in strong magnetic fields. On the other hand, MPPCs do not have such limitations and instead possess high quantum efficiency and a large compact size. Therefore, we have studied a detector system that combines an MPPC with a plastic scintillator. The system is primarily intended to be used for polarization measurements of high-energy astrophysical objects. We achieved an energy threshold of as low as ~5 keV while operating the detector at low temperature (−10 °C), reading the signal with short integration time (50 ns), and using a low-noise MPPC. We also confirmed that the light yield of our MPPC+plastic scintillator system is comparable to that obtained using a conventional PMT to read the scintillator signal. Herein, we report test results and future prospects. [ABSTRACT FROM AUTHOR]

Scintillator based coded-aperture imaging has proven to be effective when applied for X- and gamma-ray detection. Adaptation of the same method for neutron imaging has resulted in a number of propitious systems, which could be potentially employed for neutron detection in security and nuclear decommissioning applications. Recently developed scintillator based coded-aperture imagers reveal that localisation of neutron sources using this technique may be feasible, since pulse shape discrimination algorithms implemented in the digital domain can reliably separate gamma-rays from fast neutron interactions occurring within an organic scintillator. Moreover, recent advancements in the development of solid organic scintillators make them a viable solution for nuclear decommissioning applications as they present less hazardous characteristics than currently dominating liquid scintillation detectors. In this paper existing applications of coded-apertures for radiation detection are critically reviewed, highlighting potential improvements for coded-aperture based neutron source localisation. Further, the suitability of coded-apertures for neutron imaging in nuclear decommissioning is also assessed using Monte-Carlo modelling. [ABSTRACT FROM AUTHOR]

To assess the potential cytostatic properties of Pt(II) complexes with 3-hydroxymethylpyridine (3-hmpy) as the only carrier ligand, novel cis -[PtCl 2 (3-hmpy) 2 ] ( 1 ) and trans -[PtCl 2 (3-hmpy) 2 ] ( 2 ) have been prepared. Elemental analysis, FTIR spectroscopy, multinuclear NMR spectroscopy and X-ray crystallography were used to determine their structures. Based on the results obtained with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay and clonogenic assay on T24 human bladder carcinoma cells (T24), the most potent compound 2 was further tested for cytotoxicity in human ovarian carcinoma cell lines - cisplatin sensitive (IGROV 1) and its resistant subclone (IGROV 1/RDDP). The cytotoxicity of compound 2 in IGROV 1/RDDP is comparable to cisplatin. Furthermore, compound 2 induced severe conformational changes in plasmid DNA, which resulted in a delayed onset of apoptosis in T24 cells, and higher amounts of Pt in tumours and serum compared to cisplatin. In addition, in vivo antitumour effectiveness was comparable to that of cisplatin with a smaller reduction of animals' body weight, thus demonstrating that it is a promising transplatin analogue which deserves further studies. [ABSTRACT FROM AUTHOR]

A multipurpose facility for low cross section measurements has been developed at Inter University Accelerator Centre, New Delhi, India. The facility consists of a multipurpose miniature chamber equipped with 1 m focal length normal incidence Monochromator and charge coupled device based detection system which has been aligned to realize the best resolution of the spectrometer. The chamber in this facility collects radiation 100 times more efficiently from the older system, without using any extra focusing mirror assembly. It is ensured to have the provision of mounting an X-ray detector and the spectrometer transverse to the beam direction simultaneously in the same chamber. The atomic spectroscopic studies can be performed by interaction of ions beams with both thin foil and gas targets. Provision for using photomultiplier tube instead of charge coupled device, is employed in the system depending on the condition of the source strength or other detection issues. We observed the essence of a very weak atomic phenomenon, a triply excited autoionizing forbidden transition, using the above facility to demonstrate its capability for measuring such low cross section phenomena. The present developed facility covers a large spectroscopic region from X-rays to the near infrared (0.1–10,000 Å). [ABSTRACT FROM AUTHOR]

The developments in synchrotron radiation based polymer research have been profound over the last two decades. Not only have many more beamlines suitable for soft condensed matter research become available since the pioneering days but also the technical developments with respect to X-ray beam quality and position sensitive X-ray detectors have been very substantial. This has allowed to increase the degree of experimental sophistication considerably by introducing sample environments which not only allow the materials to be studied outside of equilibrium conditions but in fact in conditions which closely start to resemble realistic processing conditions. These developments now allow polymer researchers to bring synchrotron radiation based tools to the whole spectrum from academic relevant characterisations to trying to understand the effects that desired processing parameters have on the final materials. In this manuscript, which is not intended as a comprehensive history, it is described how the historic interplay between technical developments and the experimental desires has generated the soft condensed matter synchrotron radiation toolbox that is at present available by following some of the major areas that have been the subject of polymers in the last two decades. [ABSTRACT FROM AUTHOR]

The Advanced Telescope for High-Energy Astrophysics (Athena) has been selected by ESA as its second large-class mission. The future European X-ray observatory will study the hot and energetic Universe with its launch foreseen in 2028. Microcalorimeters based on superconducting Transition-edge sensor (TES) are the chosen technology for the detectors array of the X-ray Integral Field Unit (X-IFU) on board of Athena. The X-IFU is a 2-D imaging integral-field spectrometer operating in the soft X-ray band (0.3–12 keV). The detector consists of an array of 3840 TESs coupled to X-ray absorbers and read out in the MHz bandwidth using Frequency Domain Multiplexing (FDM) based on Superconducting QUantum Interference Devices (SQUIDs). The proposed design calls for devices with a high filling-factor, high quantum efficiency, relatively high count-rate capability and an energy resolution of 2.5 eV at 5.9 keV. The paper will review the basic principle and the physics of the TES-based microcalorimeters and present the state-of-the art of the FDM read-out. [ABSTRACT FROM AUTHOR]

A series of novel alkyl 5-hydroxy-7-aryl-5-methyl-1,3-dioxo-2-phenyl hexahydropyrazolo[1,2- a ][1,2,4]triazole-6-carboxylates and alkyl 5-aryl-7-methyl-1,3-dioxo-2-phenyl-1,2,3,5-tetra hydropyrazolo[1,2- a ][1,2,4]triazole-6-carboxylates have been synthesized. The synthesis of hydroxy pyrazolo[1,2- a ][1,2,4]triazoles has been achieved by DBU mediated one pot reaction of aromatic aldehydes, alkyl acetoacetates and 4-phenylurazole at 35 °C in ethanol–water (1:1). Dehydration of hydroxy pyrazolo[1,2- a ][1,2,4]triazoles has been achieved using conc. H 2 SO 4 to afford dehydrated pyrazolo[1,2- a ][1,2,4]triazoles in high yields. The structural assignments have been made by spectral data and unambiguously confirmed by X-ray analysis. Good yields, operational simplicity and moderate conditions are the advantages of the reactions. [ABSTRACT FROM AUTHOR]

Nanocomposites consisting of conductive polymers and functional nanoparticles have recently been employed in photodetectors and imagers. Here, we present a novel hybrid-organic photodetector (HPD) that was optimized for the detection of X-rays meeting the specific needs of medical imaging. Devices were fabricated using inorganic lead sulfide (PbS) nanocrystal (NC) quantum dots (QDs) and a blend of poly (3-hexylthiophene) (P3HT) and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM). Quantum dots convert X-rays directly into charge-carriers that then migrate through the organic blend to the contacting electrodes. The performance of such devices depends on the thickness and probably on the morphology of the active layer. We discuss the synthesis and characterization of the PbS quantum dots, their incorporation into a HPD, and the performance of the HPD in X-ray sensing. Scanning electron microscopy and transmission electron microscopy show the PbS-QD distribution in the organic matrix. We find a strong tendency of the QDs to phase-separate from the organic blend. [ABSTRACT FROM AUTHOR]

The main purpose of this work is to provide reference data on X-ray ionization yields and energy spectra in liquid Ar to the studies in the field of Cryogenic Avalanche Detectors (CRADs) for rare-event and other experiments, based on liquid Ar detectors. We present the results of two related researches. First, the X-ray recombination coefficients in the energy range of 10–1000 keV and ionization yields at different electric fields, between 0.6 and 2.3 kV/cm, are determined in liquid Ar based on the results of a dedicated experiment. Second, the energy spectra of pulsed X-rays in liquid Ar in the energy range of 15−40 keV, obtained in given experiments including that with the two-phase CRAD, are interpreted and compared to those calculated using a computer program, to correctly determine the absorbed X-ray energy. The X-ray recombination coefficients and ionization yields have for the first time been presented for liquid Ar in systematic way. [ABSTRACT FROM AUTHOR]

Mainly encouraged by the increasing application of ion beams for cancer treatment (hadron-therapy) including carbon beams, the use of heavy ion facilities for radiobiology is expanding rapidly today. As an alternative to dedicated centers for treatment and medical research, accelerators like GANIL offer the possibility to undertake such experiments. Since 20 years, CIMAP, reinforced 15 years ago by the biological host laboratory LARIA, has been receiving researchers in radiobiology and assisted them in performing experiments in different fields such as hadron-therapy, space radioprotection and fundamental biological and physico-chemical mechanisms. We present here a short description of the beam line and the on-line equipments that allow the automatic irradiation of up to 24 biological samples at once. We also developed an original on-line beam monitoring procedure for low ion flux (low dose rates) based on the measurement of the K-shell X-rays emitted from a thin iron foil. This detector is calibrated on an absolute scale before each experiment by counting etched tracks on an irradiated CR39 polymer plate. We present the performances and limits of this method and finally give typical fluence (dose) uncertainties for a standard irradiation in radiobiology. [ABSTRACT FROM AUTHOR]

The X-ray emissions induced by argon ions for the elements from Mg to Bi were measured on mono-elemental thin films. K-, L- and M-shells X-ray production cross section were obtained for the 40 Ar projectile energies of 32, 40, 48, 56 and 64 MeV, considering absorption corrections. For the most of target elements the approach used is based on the calculation of X-ray production cross sections through the cross section of Rutherford backscattering. The efficiency of the X-ray detector was determined using standard calibrated radioactive sources. The experimental results are compared to the predictions of the ECPSSR and PWBA theories calculated with the ISICS code. [ABSTRACT FROM AUTHOR]

Special test structures emulating the performance of C-sensor, a direct floating gate (FG) ionizing radiation sensor, were used to investigate its degradation under Gamma radiation. Original MOS transistors with bulks made of crystalline silicon and Poly allowed minimizing the number of irradiations required to study the peculiarities of charge accumulation in the dielectrics of C-sensors. Electrical characterization of the developed structures before and after the exposure to different doses of Gamma radiation was performed. The guidelines for improving sensor immunity to radiation degradation are discussed. [ABSTRACT FROM AUTHOR]

In the field of spintronics, the generation of a pure spin current (without macroscopic charge flow) through spin pumping of a ferromagnetic (FM) layer opens up the perspective of a new generation of dissipation-less devices. Microwave driven ferromagnetic resonance (FMR) can generate a pure spin current that enters adjacent layers, allowing for both magnetization reversal (through spin-transfer torque) and to probe spin coherence in non-magnetic materials. However, standard FMR is unable to probe multilayer dynamics directly, since the measurement averages over the contributions from the whole system. The synchrotron radiation-based technique of x-ray detected FMR (XFMR) offers an elegant solution to this drawback, giving access to element-, site-, and layer-specific dynamical measurements in heterostructures. In this work, we show how XFMR has provided unique information to understand spin pumping and spin transfer torque effects through a topological insulator (TI) layer in a pseudo-spin valve heterostructure. We demonstrate that TIs function as efficient spin sinks, while also allowing a limited dynamic coupling between ferromagnetic layers. These results shed new light on the spin dynamics of this novel class of materials, and suggest future directions for the development of room temperature TI-based spintronics. [ABSTRACT FROM AUTHOR]

Carbon–carbon (C/C) is used in high temperature structures. To prevent rapid oxidation of the carbon, protective coatings are applied. This paper examines such a protective coating with high energy X-ray diffraction. The coating consisted of a 0.02 mm outer layer of sodium silicate glass on a 0.2 mm layer of silicon carbide (SiC) with a 0.1 mm transition layer into the C/C of carbon fibres surrounded by a SiC matrix. It was examined in its pristine state and after heating with an oxy-acetylene torch. An area X-ray detector was used to obtain phase and strain information as a function of depth through the coating. In-plane tensile strains were observed in both a crystalline SiO 2 phase and within the SiC of the transition layer. Oxidation protection was compromised by through-thickness cracks in the SiC layer caused by the large tensile cooling strains in the layer. The strains and the density of the cracking increased after heating. However, several mechanisms were identified that moderated the strains. Based on two of these mechanisms a buffer layer of graphite between the C/C and the SiC was proposed to improve oxidation resistance. The low elastic modulus of the graphite reduces the strains in the SiC coating, which reduces the crack density, which in turn improves oxidation resistance. Adding SiC fibres to the graphite and SiC was also proposed to further reduce cracking. [ABSTRACT FROM AUTHOR]

Computed tomography (CT) is a non-invasive X-ray diagnostic technique that allows reconstructing cross sections of a patient׳s body, providing detailed information about structure and anatomy of organs and, in some extent, also about their functionality. Since the development of the first CT scanner for clinical use in the ‘70s, several improvements especially in solid-state X-ray detector technology with growing detection efficiency and fast response have led to the current configuration of modern ultra-fast, low dose whole body CT scanners. Such developments brought great advantages in the clinical settings in terms of image quality, dose effectiveness, imaging throughput, but also extending considerably the field of clinical application that were initially foreseen. Parallel to the roadmap of clinical CT technology, dedicated systems for high-resolution preclinical CT (or micro-CT) have seen a considerable growth in the last two decades, taking advantage of the modern technology of high granularity flat-panel X-ray detectors (FPD). This article aims at reviewing the milestones of the evolution of X-ray detector technology that have traced the roadmap of development of CT and micro-CT. An outlook of the current and future trends on energy resolved clinical and preclinical CT with photon counting detectors will be also given. [ABSTRACT FROM AUTHOR]

Scattered x rays are detrimental to the image quality of x-ray transmission radiography. Anti-scatter grids have been used in diagnostic x-ray imaging to improve the image quality but are not practical to use for megavoltage (MV) x-ray imaging in radiotherapy since a MV grid would be very bulky, heavy, and costly. An inherent anti-scatter detector based on Čerenkov radiation was introduced recently for MV x-ray imaging. The purpose of this work is to investigate experimentally the anti-scatter property of a single pixel prototype detector. The scatter to primary ratio (SPR) has been measured using a linear accelerator with a 6 MV x-ray beam. It has been found that the SPR for the prototype detector is 30–60% less than that of an ionization chamber, depending on the imaging geometry. This indicates the prototype detector is less sensitive to scattered radiation. [ABSTRACT FROM AUTHOR]

The use of ultrarelativistic electron (positron) emission in thin crystals to estimate particle beam spatial sizes for projected electron–positron colliders is proposed. The existing position-sensitive X-ray range detectors restrict the minimum value of the measured beam size to a level of approximately 10 μm, which is far greater than the planned sizes of collider beams. We propose to estimate the electron (positron) beam divergence over the diffracted transition radiation from angular distribution measurements. The spatial size can be obtained from the calculated beam emittance or the experimental emittance, which is measured during the earlier stage of acceleration using optical transition or optical diffraction radiation. The problem of crystal destruction under the influence of a high-intensity electron beam is discussed. The use of surface parametric X-ray radiation, where the problem of crystal destruction is almost absent, to measure the electron beam parameters is also discussed. [ABSTRACT FROM AUTHOR]

In the prospect of manufacturing ionizing radiation detectors, dense ceramics of α-HgI 2 with a strong preferred orientation were elaborated. X-ray diffraction showed that most crystallites exhibited their crystal c-axis perpendicular to the ceramic plane, which should be favorable for optimum electrical transport properties. Dark current densities about 2 nA mm −2 (under 0.2 V μm −1 bias) were measured and were shown to arise mostly from the release of carriers from trap defects (Poole–Frenkel emission). The X-ray sensitivity ≈1600 nC mGy −1 cm −2 and the μτ value ≈ 3 × 10 − 5 cm 2 V −1 were comparable to those of other forms of polycrystalline HgI 2 . The HgI 2 ceramics also exhibited a perfectly linear response as a function of the X-ray dose. [ABSTRACT FROM AUTHOR]

To obtain both a high count rate of >10 7 s −1 and a detection efficiency sufficient for high-energy X-rays of >30 keV, we propose a scintillation timing detector using a proportional-mode silicon avalanche photodiode (Si-APD) for synchrotron radiation nuclear resonant scattering. We here present results obtained with a prototype detector using a lead-loaded plastic scintillator (EJ-256) mounted on a proportional-mode Si-APD (active area size: 3 mm in diameter). The detector was operated at ‒35 °C for a better signal-to-noise ratio. Using synchrotron X-rays of 67.41 keV, which is the same energy as the first excited level of 61 Ni, we successfully measured pulse-height and time spectra of the scintillation light. A good time resolution of 0.50±0.06 ns (full width at half-maximum) was obtained for 67.41 keV X-rays with a scintillator 3 mm in diameter and 2 mm thick. [ABSTRACT FROM AUTHOR]

The edge surfaces of single crystal CdTe play an important role in the electronic properties and performance of this material as an X-ray and γ -ray radiation detector. Edge effects have previously been reported to reduce the spectroscopic performance of the edge pixels in pixelated CdTe radiation detectors without guard bands. A novel Technology Computer Aided Design (TCAD) model based on experimental data has been developed to investigate these effects. The results presented in this paper show how localized low resistivity surfaces modify the internal electric field of CdTe creating potential wells. These result in a reduction of charge collection efficiency of the edge pixels, which compares well with experimental data. [ABSTRACT FROM AUTHOR]

This work introduces a new, versatile and robust X-ray detector with hemispherical 2 π geometry, based on a set of 15 small cylindrical proportional counters located in a hexagonal and pentagonal fullerene C60 pattern, at the same distance from the center (where a sample is placed). The counteranode consists of stainless steel sewing needles with spherical tips measuring approximately 80 μm in diameter. The space between the counters and the sample could contain air, the same gas as the counters or vacuum. This allows a significant increase in the count rates by a factor approximately equal to the number of counters connected. It is shown that an energy resolution of 20% for 5.9 keV photons can be obtained, and a global counting rate of around 10 6 counts/s is achievable by the 15 Needle Anode Proportional Counters (NAPCs) operating in parallel mode, in our setup. [ABSTRACT FROM AUTHOR]

In this article, the X-ray and gamma-ray coincidence summing effect in 152 Eu is studied. Coincidence summing corrections and peak and total efficiencies of point and volume sources were determined using the direct matrices multiplication (DMM) method. The theoretically evaluated peak count rates were found to be in good agreement with the experimentally obtained values. Validation was performed by comparing the calculated efficiency curves and the corresponding correction factors with the results obtained using GESPECOR 4.2 software. [ABSTRACT FROM AUTHOR]

This paper describes a new method of threshold equalization for X-ray detectors based on the Medipix3RX ASIC, using electrical pulses to calibrate and correct for the threshold dispersion between pixels. This method involves a coarse threshold tuning, based on two 8 bits global DACs and which sets the range of variation of the threshold values; and a fine-tuning, based on two 5-bits adjustment DACs per pixel. As our fine-tuning approach is based on a state-of-the-art methodology, our coarse tuning relies on an original theoretical model. This model takes into account the noise level of the ASIC, which varies with temperature and received radiation dose. The experimental results using 300 μm Si sensor and Kα fluorescence of Zn show a global energy resolution improvement of 14% compared to previous equalization methods. We compared these results with the best achievable global energy resolution given by the resolution of individual pixels and concluded that the remaining 14% difference was due to the discretization error limited by the number of equalization bits. [ABSTRACT FROM AUTHOR]

X-ray beams propagate across a target object before they are projected onto a regularly spaced array of detectors to produce a routine X-ray image. A 3D attenuation coefficient distribution is obtained by tomographic reconstruction where scattering is usually regarded as a source of parasitic signals which increase the level of electromagnetic noise that is difficult to eliminate. However, the elastically scattered radiation could be a valuable source of information, because it can provide a 3D topology of electron densities and thus contribute significantly to the optical characterization of the scanned object. The scattering and attenuation data form a complementary base for concurrent retrieval of both electron density and attenuation coefficient distributions. In this paper we developed the 3D reconstruction method that combines both data inputs and produces better image resolution compared to traditional technology. [ABSTRACT FROM AUTHOR]