Types Of Detectors Research Articles

A passive single-cylindrical neutron spectrometer for photoneutron spectrometry in 10 MV Elekta Precise Linac head

Measuring the neutron spectrum on the Linac head using a passive type neutron detector is relatively easier than an active type detector because it does not require the involvement of operators who work in a high radiation area. Neutron spectrum measurements with passive foil activation neutron detectors in a single-moderator are more practical and easier than multi-foil techniques. This technique is quite simple, easy to make, low cost, and the measurement time is relatively short. This spectrometer is designed by placing seven passive Au detectors at varying depths in a single-cylindrical moderator. The response function for each detector is calculated by MCNPX 2.7 program and used ENDF7 as a nuclear data library. Detector foil activity was measured using a gamma spectrometer, and the neutron spectrum was obtained using the unfolding technique using the UMG 3.3 program. The results of measuring the neutron spectrum measurements have been carried out at a position 10 cm below the head of the Elekta Precise 10 MV Linac was 2.73 × 105 n/cm2·s, where the fast neutron from these results are 4% higher when compared to the simulation results using PHITS.

Ancilla quantum measurements on interacting chains: Sensitivity of entanglement dynamics to the type and concentration of detectors

Ancilla quantum measurements on interacting chains: Sensitivity of entanglement dynamics to the type and concentration of detectors

Flexible visible and near-infrared laser detector based on bismuth sulphide nanorods

The development of a flexible, visible and near-infrared laser detector with fast response holds significant potential for applications in wearable electronics, binary switches, and other fields. In this study, we utilized a flexible transparent polyimide (PI) substrate known for its exceptional thermal resistance up to 400 °C to fabricate an innovative type of flexible laser detector. Systematic investigations demonstrate that the bismuth sulphide nanorods-based laser detector exhibits not only high flexibility and light-weight properties but also excellent linear current characteristics and strong photosensitive dependence on laser light intensity. This research presents a novel approach for the fabrication of high-performance flexible optoelectronic devices.

Environmentally resilient data collecting system optimized for measuring low density neutron flux

In this work we detailed present the data collecting system (DCS), designed and optimized for use with a helium neutron counter even under very challenging environmental conditions. The DCS, in addition to its simplicity, allows for the flexible configuration of multiple DCS units into a single measurement system and can also interface with various types of detectors and different data acquisition systems as per the experimental requirements. The main advantages of the presented DCS include its autonomy, remote control capability, and modularity. The pulse shape analysis procedure employed within the DCS enhances measurement sensitivity, which is crucial for detecting extremely low neutron fluxes, such as those in underground laboratories.

Comparison Flattening Filter and Flattening Filter-Free Techniques in Small-Fields Dosimetry with Various Types of Detectors.

The aim of this study was to investigate the detector size effect on small-field dosimetry and compare the performance of 6MV WFF/FFF techniques. We investigated the detector size effect on small-field dosimetry and compared the performance of 6MV WFF/FFF techniques. PDD, profile curves, and absorbed dose were measured in water under reference conditions with 6MV (WFF/FFF) techniques. We employed Farmer FC65-P, CC13, CC01, and IBA Razor diode, with Versa Lineac. Subsequently, we replicated this assessment for small-fields under 5cmx5cm dimensions. For both 6MV WFF/FFF, significant dose differences (Dmax=1.47cm), were ±4.55%, ±6.7, ±12.75% and ±33.3% for 4cmx4cm, 3cmx3cm, 2cmx2cm, and 1cmx1cm, respectively. The average difference relative to D10 was observed to be ±4.66%, ±5.73%, ±6.58%, and ±8.75% for the previous field sizes. Differences between WFF/FFF are neglected values at all field sizes>2.3%, also, the output of the largest detector FC65-P is lower at 55% in the smallest field size. Variation in the profile doesn't exceed a difference of >5% in flatness between WFF/FFF at depth10cm, across all fields, while symmetry is >1%, but radiation output is considerably lower at 55% for FC65-P chamber in 2cmx2cm, 1cmx1cm compared to the CC01 chamber and Razor diode. Significant differences in 1cmx1cm, where FC65-P chamber exhibits around 49% difference compared to Razor diode with 6MV (WFF/FFF). Conclusions: Significant differences were observed in doses with various detectors. Detector-size influences the dose. WFF/FFF techniques show no major differences in small-fields dosimetry. Utilize some situations the advantage of FFF boasting a higher dose rate, consequently reducing treatment time to half.

Ultrahigh-Resolution K-Edge Imaging of Coronary Arteries With Prototype Deep-Silicon Photon-Counting CT: Initial Results in Phantoms.

Background Photon-counting CT (PCCT) represents a recent advancement in CT, offering improved spatial resolution and spectral separability. By using multiple adjustable energy bins, PCCT enables K-edge imaging, allowing mixed contrast agent distinction. Deep-silicon is a new type of photon-counting detector with different characteristics compared with cadmium photon-counting detectors. Purpose To evaluate the performance of a prototype deep-Si PCCT scanner and compare it with that of a state-of-the-art dual-energy energy-integrating detector (EID) scanner in imaging coronary artery plaques enhanced with iodine and K-edge contrast agents. Materials and Methods A series of 10 three-dimensional-printed inserts (diameter, 3.5 mm) was prepared, and materials mimicking soft and calcified plaques were added to simulate stenosed coronary arteries. Inserts filled with an iodine- or gadolinium-based contrast agent (GBCA) were scanned. Virtual monoenergetic images (VMIs) and iodine maps were generated using two- and eight-energy bin data from EID CT and PCCT, respectively. Gadolinium maps were calculated for PCCT. The CT numbers of VMIs and iodine maps were compared. Spatial resolution and blooming artifacts were compared on the 70-keV VMIs in plaque-free and calcified coronary arteries. Results No evidence of a significant difference in the CT number of 70-keV images was found except in inserts containing GBCAs. In the absence of a GBCA, excellent (r > 0.99) agreement for iodine was found. PCCT could quantify the GBCA within 0.2 mg Gd/mL ± 0.8 accuracy of the ground truth, whereas EID CT failed to detect the GBCA. Lumen measurements were more accurate for PCCT than for EID CT, with mean errors of 167 versus 442 µm (P < .001) compared with the 3.5-mm ground truth. Conclusion Deep-Si PCCT demonstrated good accuracy in iodine quantification and could accurately decompose mixtures of two contrast agents. Its improved spatial resolution resulted in sharper images with blooming artifacts reduced by 50% compared with a state-of-the-art dual-energy EID CT scanner. © RSNA, 2024.

Halide perovskite x-ray detectors: Fundamentals, progress, and outlook

Halide perovskites have demonstrated great potential in x-ray detectors, due to their high x-ray attenuation coefficient, large bulk resistance, ultralong carrier diffusion length, and adjustable bandgap. Moreover, their abundant raw materials and simple processing combined with excellent compatibility with integrated circuits make them ideal for cost-efficient and high-efficiency real-world imaging applications. Herein, we comprehensively reviewed advances and progress in x-ray detection devices based on halide perovskites. We expound on the fundamental mechanisms of interactions between x rays and matter as background and indicate different parameters for different types of x-ray detectors, which guides the basic requirements on how to select and design suitable materials for active layers. After emphasizing the superb properties of halide perovskites through the shortcomings of commercial materials, we evaluate the latest advancements and ongoing progress in halide perovskites with different dimensions and structures for both direct and indirect x-ray detectors, and discuss the effect of dimensional varieties on the device performance. We also highlight current challenges in the area of perovskite x-ray detectors and propose corresponding solutions to optimize halide perovskites and optimize x-ray detectors for next-generation imaging applications.

Stability indicating for Quality Control Assessment of three antidiabetic molecules using HPLC technique: Stability Assessment of three antidiabetic molecules

Diabetes mellitus responds better to co-formulated tablet dosages of dapagliflozin (DFZN), metformin (MFMN), and vildagliptin (VDGN). For the purpose of studying stability and quantifying DFZN, VDGN, and MFMN in bulk forms and in dosage forms, an efficient and fast HPLC method of analysis is currently developed. The mobile phase featured 80:20 (v/v) 0.2 M, pH 3.0, ammonium acetate buffer and acetonitrile mixed together and Luna's HPLC C-18 column, named Phenyl hexyl, was utilised for DFZN, VDGN, and MFMN separation and its quantification. The PDA type detector operating at 235 nm wavelength was deployed. The “International Conference on Harmonisation” recommendations were strictly adhered throughout the validation process. A strong linear association between response and quantity in the range of 2.5–15 µg/ml (DFZN), 25–150 µg/ml (VDGN), and 125–750 µg/ml (MFMN) is supported by the regression information for the DFZN, VDGN, and MFMN calibration plots. The precision, selectivity, accuracy, sensitivity, ruggedness and robustness were satisfactory for the method. The tablet sample of DFZN, VDGN, and MFMN was subjected to acid, water, base, sodium bisulfite, light, dry heat and peroxide degradations. Significant differences in retention times were observed between the well-resolved peaks of the degradants and the primary peaks (DFZN, VDGN, and MFMN). Thus, the assay might be characterised as stability indicating. The contents of DFZN, VDGN, and MFMN in dosage forms were assessed precisely and accurately by currently developed HPLC technique. This technique may be applied to ensure the quality of formulation doses for DFZN, VDGN, and MFMN contents.

Machine Learning Based Compton Suppression for Nuclear Fusion Plasma Diagnostics

Diagnostics are critical on the path to commercial fusion reactors, since measurements and characterisation of the plasma is important for sustaining fusion reactions. Gamma spectroscopy is commonly used to provide information about the neutron energy spectrum from activation analysis, which can be used to calculate the neutron flux and fusion power. The detection limits for measuring nuclear dosimetry reactions used in such diagnostics are fundamentally related to Compton scattering events making up a background continuum in measured spectra. This background lies in the same energy region as peaks from low-energy gamma rays, leading to detection and characterisation limitations. This paper presents a digital machine learning Compton suppression algorithm (MLCSA), that uses state-of-the-art machine learning techniques to perform pulse shape discrimination for high purity germanium (HPGe) detectors. The MLCSA identifies key features of individual pulses to differentiate between those that are generated from photopeaks and Compton scatter events. Compton events are then rejected, reducing the low energy background. This novel suppression algorithm improves gamma spectroscopy results by lowering minimum detectable activity (MDA) limits and thus reducing the measurement time required to reach the desired detection limit. In this paper, the performance of the MLCSA is demonstrated using an HPGe detector, with a gamma spectrum containing americium-241 (Am-241) and cobalt-60 (Co-60). The MDA of Am-241 improved by 51% and the signal to background ratio improved by 49%, while the Co-60 peaks were partially preserved (reduced by 78%). The MLCSA requires no modelling of the specific detector and so has the potential to be detector agnostic, meaning the technique could be applied to a variety of detector types and applications.

The Optimization of Pair Distribution Functions for the Evaluation of the Degree of Disorder and Physical Stability in Amorphous Solids.

The amorphous form of poorly soluble drugs is physically unstable and prone to crystallization, resulting in decreased solubility and bioavailability. However, the conventional accelerated stability test for amorphous drugs is time-consuming and inaccurate. Therefore, there is an urgent need to develop rapid and accurate stability assessment technology. This study used the antitumor drug nilotinib free base as a model drug. The degree of disorder and physical stability in the amorphous form was assessed by applying the pair distribution function (PDF) and principal component analysis (PCA) methods based on powder X-ray diffraction (PXRD) data. Specifically, the assessment conditions, such as the PDF interatomic distance range, PXRD detector type, and PXRD diffraction angle range were also optimized. The results showed that more reliable PCA data could be obtained when the PDF interatomic distance range was 0-15 Å. When the PXRD detector was a semiconductor-type detector, the PDF data obtained were more accurate than other detectors. When the PXRD diffraction angle range was 5-40°, the intermolecular arrangement of the amorphous drugs could be accurately predicted. Finally, the accelerated stability test also showed that under the above-optimized conditions, this method could accurately and rapidly assess the degree of disorder and physical stability in the amorphous form of drugs, which has obvious advantages compared with the accelerated stability test.

Cranial Computer Tomography with Photon Counting and Energy-Integrated Detectors: Objective Comparison in the Same Patients.

This study provides an objective comparison of cranial computed tomography (CT) imaging quality and radiation dose between photon counting detectors (PCCTs) and energy-integrated detectors (EIDs). We retrospectively analyzed 158 CT scans from 76 patients, employing both detector types on the same individuals to ensure a consistent comparison. Our analysis focused on the Computed Tomography Dose Index and the Dose-Length Product together with the contrast-to-noise ratio and the signal-to-noise ratio for brain gray and white matter. We utilized standardized imaging protocols and consistent patient positioning to minimize variables. PCCT showed a potential for higher image quality and lower radiation doses, as highlighted by this study, thus achieving diagnostic clarity with reduced radiation exposure, underlining its significance in patient care, particularly for patients requiring multiple scans. The results demonstrated that while both systems were effective, PCCT offered enhanced imaging and patient safety in neuroradiological evaluations.

Split ring hole metamaterial-enhanced pyroelectric detector for efficient multi-narrowband terahertz detection

Derived from infrared pyroelectric detection, typical terahertz (THz) pyroelectric detectors have low sensitivity at low-frequency THz bands. Based on the high-efficiency absorption of the metamaterial perfect absorber (MPA), a novel split ring hole metamaterial-enhanced pyroelectric detector is proposed to achieve efficient multi-narrowband THz detection. Using high frequency simulation software (HFSS), the dimensional parameters including ring radius, ring width, connection beam width, array period, and thickness, are optimized to enhance efficient multi-narrowband absorption. The as-optimized metamaterial-enhanced detectors are fabricated via micro-nano manufacturing technology. The voltage responsiveness and noise equivalent power of the metamaterial-enhanced detector are tested by THz focused optical path and compared with those of the typical pyroelectric detector and the simulated MPA absorptivity. The results indicate that the metamaterial-enhanced detector has a multi-narrowband detection capability at 0.245 THz, 0.295 THz, and 0.38 THz, which is close to the simulated MPA absorptivity. Compared to the typical pyroelectric detector, the split ring hole metamaterial-enhanced detector can simultaneously achieve thermal absorption, thermal conduction, and pyroelectricity in the same MPA structure, providing faster response speed above 100 Hz chopper frequency and two times higher detection sensitivity at multi-narrowband THz frequencies. This research can be used for THz sensing, absorption filtering, biological macromolecule detection, and other applications.

Uncertainty of scintillator-based field-output factor measurements in MR-Linacs with the two-channel chromatic stem removal technique

Current international protocols such as the IAEA/AAPM TRS-483 for small field dosimetry do not include recommendations for measurements in strong magnetic fields as found in MR-Linacs (i.e. megavoltage x-ray radiotherapy units with built-in magnetic resonance imaging). A EURAMET research project was therefore launched to support the traceability of such measurements and to contribute to the metrological basis for future recommendations. Given the high degree of water equivalence and the small size of fiber-coupled plastic scintillators, one objective of the project was to study the suitability of this detector type for dosimetry in MR-Linacs and to demonstrate their use in a clinical environment. This manuscript reports results of that work. A protocol for measuring field output factors with plastic scintillation detectors was developed. The protocol is based on calibration of the scintillators directly in a water phantom positioned in the MR-Linac rather than in a water-equivalent solid phantom as has been a common technique for conventional linacs. A detailed uncertainty budget was established involving all known sources of uncertainty including the systematic influence of light attenuation through the fiber when measuring in different field sizes. The protocol was used to measure field output factors at five MR-Linac's (four Viewray MRIdian's and one Elekta Unity). The protocol showed a high level of robustness leading to a less than 0.3 % deviation between field output factors calculated based on calibration data obtained before or after the field-output factor measurements. The correction for light attenuation was less than 0.4 % for all fields measured but showed a systematic offset, with larger corrections needed for small field sizes.This robustness of the protocol was further demonstrated by the closeness of agreement (agreement within uncertainty) for field-output factor measurements with two different scintillators (BCF-12 and BCF-60) for square fields (size: 0.83 cm × 0.83 cm or larger) in four nominally identical Viewray MRIdian's. To test the accuracy of the scintillator measurements, the system was used for characterization of a PTW 60019 micro diamond detector in a Viewray MRIdian. Scintillator based correction factors for output factor measurements with the micro diamond detector were found to be in agreement with independent Monte-Carlo computations. The study therefore supports that plastic scintillation detectors are an excellent option for measuring field output factors in MR-Linacs.

Natural radioactivity level in Yemen: A systematic review of radiological studies

This paper aimed to conduct a systematic review of 26 published articles from 13 different regions in the Republic of Yemen related to the study of natural radioactivity (NORM) and enhanced artificial radioactivity (TENORM). The study relied on the analysis of various sample types, including air, groundwater, surface water, hot spring water, soil, sand, rocks, building materials, and oil field samples. It also analyzed the study areas, the types of detectors employed, and the study's timeframe. The analytical results raised significant concerns regarding the high levels of radioactivity observed in many of the studied regions. Moreover, some regions indicated the absence of any prior radiological study, despite apparent effects on the population and the environment, which suggest the presence of potential radionuclide concentration. Based on this study, it is strongly recommended that researchers conduct further radiological studies in regions previously studied over extended periods and in areas where no prior radiological studies have been conducted to assess potential radionuclide concentration.

Traffic state estimation from vehicle trajectories with anisotropic Gaussian processes

Accurately monitoring road traffic state is crucial for various applications, including travel time prediction, traffic control, and traffic safety. However, the lack of sensors often results in incomplete traffic state data, making it challenging to obtain reliable information for decision-making. This paper proposes a novel method for imputing traffic state data using Gaussian processes (GP) to address this issue. We propose a kernel rotation re-parametrization scheme that transforms a standard isotropic GP kernel into an anisotropic kernel, which can better model the congestion propagation in traffic flow data. The model parameters can be estimated by statistical inference using data from sparse probe vehicles or loop detectors. Moreover, the rotated GP method provides statistical uncertainty quantification for the imputed traffic state, making it more reliable. We also extend our approach to a multi-output GP, which allows for simultaneously estimating the traffic state for multiple lanes. We evaluate our method using real-world traffic data from the Next Generation simulation (NGSIM) and HighD programs, along with simulated data representing a traffic bottleneck scenario. Considering current and future mixed traffic of connected vehicles (CVs) and human-driven vehicles (HVs), we experiment with the traffic state estimation (TSE) scheme from 5% to 50% available trajectories, mimicking different CV penetration rates in a mixed traffic environment. We also test the traffic state estimation when traffic flow information is obtained from loop detectors. The results demonstrate the adaptability of our TSE method across different CV penetration rates and types of detectors, achieving state-of-the-art accuracy in scenarios with sparse observations.

Accurate machine-specific reference and small-field dosimetry for a self-shielded neuro-radiosurgical system.

The newly available ZAP-X stereotactic radiosurgical system is designed for the treatment of intracranial lesions, with several unique features that include a self-shielding, gyroscopic gantry, wheel collimation, non-orthogonal kV imaging, short source-axis distance, and low-energy megavoltage beam. Systematic characterization of its radiation as well as other properties is imperative to ensure its safe and effective clinical application. To accurately determine the radiation output of the ZAP-X with a special focus on the smaller diameter cones and an aim to provide useful recommendations on quantification of small field dosimetry. Six different types of detectors were used to measure relative output factors at field sizes ranging from 4to 25mm, including the PTW microSilicon and microdiamond diodes, Exradin W2 plastic scintillator, Exradin A16 and A1SL ionization chambers, and the alanine dosimeter. The 25mm cone served as the reference field size. Absolute dose was determined with both TG-51-based dosimetry using a calibrated PTW Semiflex ion chamber and measurements using alanine dosimeters. The average radiation output factors (maximum deviation from the average) measured with the microDiamond, microSilicon, and W2 detectors were: for the 4mm cone, 0.741 (1.0%); for the 5mm cone: 0.817 (1.0%); for the 7.5mm cone: 0.908 (1.0%); for the 10mm cone: 0.946 (0.4%); for the 12.5mm cone: 0.964 (0.2%); for the 15mm cone: 0.976 (0.1%); for the 20mm cone: 0.990 (0.1%). For field sizes larger than 10mm, the A1SL and A16 micro-chambers also yielded consistent output factors within 1.5% of those obtained using the microSilicon, microdiamond, and W2 detectors. The absolute dose measurement obtained with alanine was within 1.2%, consistent with combined uncertainties, compared to the PTW Semiflex chamber for the 25mm reference cone. For field sizes less than 10mm, the microSilicon diode, microDiamond detector, and W2 scintillator are suitable devices for accurate small field dosimetry of the ZAP-X system. For larger fields, the A1SL and A16 micro-chambers can also be used. Furthermore, alanine dosimetry can be an accurate verification of reference and absolute dose typically measured with ion chambers. Use of multiple suitable detectors and uncertainty analyses were recommended for reliable determination of small field radiation outputs.

Development of a microfurnace dedicated to in situ scanning electron microscope observation up to 1300 °C. III. In situ high temperature experiments.

The FurnaSEM microfurnace was installed in the chamber of a scanning electron microscope to carry out in situ experiments at high temperatures and test its limits. The microfurnace was used in combination with different types of detectors (Everhart-Thornley for the collection of secondary electrons in a high vacuum, gas secondary electron detector for the specific collection of secondary electrons in the presence of gas, and Karmen© detector for the collection of backscattered electrons at high temperature). Experiments carried out on various samples (metal alloys and ceramics) show that the microfurnace operates in both high-vacuum and low-vacuum modes. Temperature ramp rates during temperature cycles applied to the sample range from 1 to 120 °C/min (temperature rise) and 1 to 480 °C/min (controlled and natural cooling). The maximum temperature at which images were recorded up to 25k × magnification was 1340 °C, with a residual air atmosphere of 120Pa. The choice of a flat furnace with the sample placed directly above it has enabled innovative experiments to be carried out, such as low-voltage imaging (using a shorter working distance-up to 10 mm-than is possible with conventional furnaces), 3D imaging (by tilting the stage by up to 10°), and high-temperature backscattered electron imaging (using a dedicated detector).

16: MC simulations of detector type specific output correction factors in the presence of magnetic field

16: MC simulations of detector type specific output correction factors in the presence of magnetic field

Re-decoupling the classification branch in object detectors for few-class scenes

Few-class object detection is a critical task in numerous scenes, such as autonomous driving and intelligent surveillance. The current researches mainly focus on the correlation or decoupling between classification and regression subtasks in object detection. However, they rarely take advantage of the potential of re-decoupling the classification subtask. In this paper, we propose to re-decouple the classification branch in object detection for few-class scenes by reducing multi-classification features to multiple binary-classification features. Since multi-classification losses cannot supervise the network to learn decoupled binary-classification features, we introduce a single-class loss to supervise decoupled multiple binary-classification branches. In particular, we propose a basic feature degradation head (FD-Head) structure that decouples the classification branches and applies binary-classification loss to encourage each branch to learn only the degraded single-class features. In addition, based on the mutual exclusion between classes, we propose a mutual exclusion constraint (FD-Head-M) module to constrain the scores of all classes, promoting the detector performance. Finally, we replace the original convolution with more powerful feature extraction modules to form the enhanced FD-Head (FD-Head-E). Notably, our method can be used as a universal module and embedded into the existing object detectors to boost their performance. When applying our method to typical object detectors, it experimentally achieves performance gains of 1.2–2.2%, 1.7–2.5% on the KITTI-3, SeaShips datasets respectively. When using ResNet50 as the backbone network, our method gains an accuracy of 45.9% on the MS COCO dataset.

Long-term irradiation study of sMDT drift tubes with an integrated accumulated charge of 60 C per wire using beta-electrons from a 90Sr source

Two ATLAS sMDT drift tubes have been irradiated for almost 1 year using a 90Sr beta-decay source. An integrated charge of 62C has been accumulated on each of both anode wires over an anode-wire region of about 7.5 cm. Taking into account the intensity distribution of the irradiation corresponds to a maximum accumulated line charge density of about 14C/cm. At the innermost position of the ATLAS forward muon spectrometer 10C/cm are expected for 10 years of high-luminosity LHC operation and for this detector type at gas gain 20000. To investigate potential outgassing, the endplug region of the drift-tubes, where no gas amplification occurs, was irradiated additionally using about half the beta-electrons emitted from the source. The other beta-electrons were irradiating an active part of the gas volume for monitoring purpose. During four months the endplugs were irradiated by 5C/cm equivalent. All observed anode currents were very stable over the whole period of irradiation and thus no sign of deterioration in the performance of both drift tubes was observed. This indicates that no ageing effects occurred and that no performance loss due to outgassing of any plastic surfaces has been observed. All components that have potential contact to the detector gas Ar:CO2 with a mixture of 93:7 (percent volume) have been carefully and properly chosen. The required cleanliness of all tube- and gas components has been achieved during construction and operation of these drift tubes.