Gamma-ray Sensor Research Articles

A novel metering system consists of capacitance-based sensor, gamma-ray sensor and ANN for measuring volume fractions of three-phase homogeneous flows

ABSTRACT Measuring the volume fraction of different types of fluids with two or three phases is so vital. Among all available methods, two of them, capacitance-based and gamma-ray attenuation, are so popular and widely used. Moreover, nowadays, AI which stands for Artificial Intelligence can be seen almost in all areas, and the measuring section is no exception. In this paper, the main goal is to predict the volume fraction of a three-phase homogeneous fluid which contains water, oil, and gas materials. To opt for an optimised method, a combination of capacitance-based sensors, gamma-ray attenuation sensor and Artificial Neural Networks (ANN) is utilised. To train the proposed metering system which is a MLP type, two inputs are considered. For the first input, the concave sensor is simulated in COMSOL Multiphysics software and different combinations of three phases (different volume fractions) are applied. Then through theoretical investigations of gamma-ray sensor, Barium-133 which radiates 0.356 MeV is used. This way, the second required input is generated. Finally, to implement a new and accurate metering system, a number of networks with different characteristics are run in the MATLAB software. The best structure had a Mean Absolute Error (MAE) equal to 0.33, 3.68 and 3.75 for the water, gas and oil phases, respectively. The accuracy of the presented metering system is illustrated by the received outcomes. The novelty of this study is proposing a new combined method that can measure a three-phase homogeneous fluid’s volume fractions containing water, gas and oil, precisely.

Validation of a new gamma ray soil bulk density sensor

AbstractSoil compaction and soil bulk density are key soil properties affecting soil health and soil ecosystem services like crop production, water retention and purification and carbon sequestration. The standard method for soil bulk density measurements using Kopecky rings is very labour intensive, time consuming and leaves notable damage to the field. Accurate data on bulk density are therefore scarce. To enable large‐scale data collection, we tested a new portable gamma ray sensor (RhoC) for in situ field and dry bulk density measurements up to 1 m depth. In this first validation study, measurements with the RhoC‐sensor were compared with classic ring sampling. Measurements were made in two agricultural fields in the Netherlands (a sandy clay loam and a sandy soil), with large variation in subsoil compaction. At 10 locations within each field, three soil density profiles were made. Each profile comprised six depth measurements (every 10 cm from 10 to 60 cm depth) using the RhoC‐sensor and Kopecky rings, resulting in 30 pairwise profiles and 180 measurements in total per field. At an average soil density of 1.5 g/cm3, the relative uncertainty was 9% for the Kopecky rings and 15% for the RhoC‐sensor. Because the RhoC‐sensor is easy and quick to use, the higher relative uncertainty can easily be compensated for by making additional measurements per location. In conclusion, the RhoC‐sensor allows a reliable quantitative in situ assessment of both field and dry bulk density. This provides the much‐needed possibility for rapid and accurate assessment of soil compaction. The acquisition of this data supports the calculation of soil organic carbon stocks and is indispensable for (national) soil monitoring, to assess soil health and to inform sustainable land management practices for sustained or improved soil health and provision of soil ecosystem services, such as requested in the proposed EU Directive on Soil Monitoring and Resilience.

Imaging of 3 bright terrestrial gamma-ray flashes by the atmosphere-space interactions monitor and their parent thunderstorms

The Atmosphere-Space Interactions Monitor (ASIM) on the International Space Station (ISS) includes an instrument designed to geolocate Terrestrial Gamma-ray Flashes (TGF) produced by thunderstorms. It does so with a coded aperture system shadowing the pixelated Low Energy Detector of the Modular X- and Gamma-ray Sensor (MXGS). Additionally, it locates associated lightning flashes with the Modular Multispectral Imaging Array (MMIA). Here we present 3 bright TGFs with very similar duration, fluency and observation distance. The innovative imaging capabilities allow us to determine the TGF position and correlate the TGF-lightning parent event in time and position simultaneously. The accurate position determination and distance to the observer allow us to perform a comparative study of TGF characteristics. These TGFs were produced in association with lightning flashes below the highest cloud tops of developing to mature convective cells. In one event, GLM (Geostationary Lightning Mapper) cloud flash rates were slowing down after the TGF while negative cloud-to-ground flashes suddenly ceased from 10 to 5 min before the TGF. An 8-stroke (strongest: -93 kA) cloud-to-ground flash occurred 31 s before the TGF. Vertical profiles from the ERA5 reanalysis data suggest TGFs may be produced in variety of tropical environments.

Simulation of charge sharing effects in 70 μm pixelated CdTe sensor

Pixel detectors become an integral part of medical imaging, nondestructive testing, space science and particle physics. Sensors that are bump bonded to readout ASICs are made from various materials such as GaAs, Si, CdTe, and CdZnTe. Current research tends to use CdTe/CdZnTe as gamma-ray sensors due to its high absorption coefficient in the gamma spectrum. With decreasing size of pixel pitch, charge diffusion and secondary fluorescent photons cause charge sharing between neighboring pixels. That decreases the spatial and spectral resolution of the detector. This study simulated the effects of charge diffusion in a 2 mm thick 70 μm pixelated CdTe using TCAD. We created a 3D model of the sensor with an array of 5 × 5 pixels. We simulated the propagation of e-h pairs generated upon the absorption of gamma photons in CdTe. Based on the simulation outcome, we calculated the collection time, drift time and pixel capacitance. Finally, we propose a sensor model for use in analog front-end design.

Feasibility assessment on use of proximal geophysical sensors to support precision management

AbstractA study was conducted at three sites in North Dakota to strengthen understanding of the usefulness of different proximal geophysical data types in agricultural contexts of varying pedology. This study hypothesizes that electromagnetic induction (EMI), gamma‐ray sensor (GRS), cosmic‐ray neutron sensor (CRNS), and elevation data layers are all useful in multiple linear regression (MLR) predictions of soil properties that meet expert criteria at three agricultural sites. In addition to geophysical data collection with vehicle‐mounted sensors, 15 soil samples were collected at each site and analyzed for nine soil properties of interest. A set of model training data was compiled by pairing the sampled soil property measurements with the nearest geophysical data. Eleven models passed expert‐defined uncertainty criteria at Site 1, 16 passed at Site 2, and 14 passed at Site 3. Electrical conductivity (EC), organic matter (OM), available water holding capacity, silt, and clay were predicted at Site 1 with an R‐squared of prediction > .50 and acceptable root mean square error of prediction (RMSEP). Bulk density (BD), OM, available water capacity, silt, and clay were predicted with > .50 and acceptable RMSEP at Site 2. At Site 3, no soil properties were predicted with acceptable RMSEP and an > .50. These results confirm feasibility of our method, and the authors recommend the prioritization of EMI data collection if geophysical data collection is limited to a single mapping effort and calibration soil samples are few.

Thermal neutron activation of a CeBr[formula omitted] gamma-ray sensor

We observed significant activation of a CeBr3 gamma-ray sensor following exposure to thermal neutrons with a fluence of 105 cm−2 over a 40-minute-long period. Following irradiation, the intrinsic background rate increased from 30 to 18,100 counts s−1. Pulse height spectra of the activated detector were collected over a 45-minute-long period following neutron irradiation, and the spectra showed evidence for radioactive decay products produced via both β decay and gamma decay of meta-stable excited states (isomeric transitions). The decay energies and half lives revealed the presence of 80Br (t1/2=17 min), 80Br* (t1/2=4.4 h), 82Br (t1/2=6.1 min), and 139Ce (t1/2=55 s). The presence of additional, longer-lived radioisotopes cannot be ruled out by our measurements. All of the observed activation products were formed via neutron capture on primary detector elements, and thus would be expected for any CeBr3 sensor exposed to similar (or higher) thermal neutron flux environments. Given the dramatic increase in intrinsic count rates that we observed following the relatively modest neutron exposure, we propose that CeBr3-based gamma-ray sensors may not be suitable for use in environments with high thermal neutron fluxes without the inclusion of a thermal neutron shield surrounding the sensor.

Structural, morphological, electrical and optical properties of Zn doped CdTe thin films

Cadmium Zinc Telluride (CdZnTe) is a ternary Ⅱ- Ⅵundeviating band gap semiconductor with cubic Zinc blende formation and it is a propitious material for ambient temperature xray as well as gamma ray sensor detectors. Cadmium Zinc Telluride (CdZnTe) thin layer coating were developed on nickel substrate by chemical bath deposition in non-aqueous approach. The as grown films were inspected by X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Scanning electron microscope, Fourier transform infrared spectroscopy (FTIR), PL spectra, UV spectra, Raman spectroscopy and FourProbe analysis. Studies tell that as grown films are poly-crystalline in nature along with cubic zinc blende formation. The structural properties like crystallite size, lattice constant, micro strain as well as dislocation density were evaluated. FESEM and SEM analysis reveals that the as developed films are smooth and equal sized uniform spherical grains distributed in single state as well as in cluster form. The average size of grain film is observed to be 12.33 nm. Optical study reveals the broad transmittance escorted by the band gap energy of 2.2eV. Electrical study reveals that resistivity of as grown film is 5.1×105 Ω-cm at room temperature.

High-gas-volume-fraction measurement of wet gas using a gamma-ray sensor at different mounting angles

With the development of oil and gas fields in the South China Sea, the focus is on measurement accuracy pertaining to wet gas around subsea wellheads. Owing to limited space and safety with regard to subsea installations, the horizontal installation of a wet gas meter is preferred. However, the phase distribution of wet gas with a high gas volume fraction (GVF) in a horizontal pipe is non-homogeneous and causes uncertainty in the measurement of void fraction using the single-beam gamma-ray method. To resolve this issue, this study aims to determine a sensor position to best estimate the gas void fraction of a wet gas flow. An experiment was designed and conducted to study measurement results by mounting a gamma-ray sensor at different angles. A computational fluid dynamics numerical simulation was performed to investigate the phase distribution at the Venturi throat, and the resulting GVF based on the slip ratio and void fraction was used for comparative analysis considering the input void fraction as reference. The comparative analysis shows that the measurement errors at mounting angles of 0° and 90° are large in numbers, and optimal results are achieved at 45°. Therefore, to obtain accurate measurement results in horizontal pipes, an optimal mounting angle of gamma-ray source and detector relative to horizontal is recommended for the single-beam gamma-ray void fraction measurement method.

Development of compact sensor with CdS photoresistor for high gamma-ray field monitoring

A compact gamma-ray sensor composed of a cadmium sulfide (CdS) photoresistor and a small-sized cesium iodine doped thallium scintillator is introduced for intense gamma-ray monitoring. The sensor exhibits radiation-resistant ability and a linear output response over a wide dose range. The dose rate at several conditions was measured for confirmation of feasibility. Experimental results demonstrated its advantage for gamma-ray measurements in intense fields as an inexpensive, robust, compact, and high-sensitivity device.

Gamma-Ray Sensor Using YAlO3(Ce) Single Crystal and CNT/PEEK with High Sensitivity and Stability under Harsh Underwater Conditions.

A new gamma-ray sensor, which could be employed in harsh underwater conditions, was developed using YAlO3(Ce) single crystal and carbon nanotube reinforced polyetheretherketone (CNT/PEEK). The sensor is compact, highly sensitive and stable, by providing real-time gross counts and an accumulated spectrum for fresh, saline, or contaminated water conditions. The sensor was tested in a water tank for quantification of the limit of detections. The Φ51 × 51 mm2 YAlO3(Ce) crystal exhibits a nearly perfect proportionality with a correlation of over 0.999 in terms of light yield per energy and possesses a high energy resolution. The chemically stable CNT/PEEK window material further enhances the detection efficiency by minimizing the background counts from penetrating gamma-rays. Data timeliness was obtained for regulation-based minimum detectable activity targets within 300 s. For a source-detector distance of up to 300 mm in water, the gross counts demonstrate the existence of radionuclides (Cs-137 and Co-60), owing to their higher efficiency (max. ~15 times) than those of the photopeak counts. Such differences between efficiency values are more likely in water than in air because of the high density of water, resulting in an increased build-up of scattered photons. The proposed sensor is suitable for autonomous underwater systems.

Performance comparison of capacitance-based flowmeter with gamma-ray attenuation-based two-phase flowmeter for determining volume fractions in an annular flow regime’s components

Precise metering of the void fraction is one of the important problems in the oil, chemical and petrochemical industries. For void fraction measurement, there are different kinds of sensors with different configurations. In this regard, the capacitance-based sensor and gamma-ray attenuation-based sensor are very well known as two most accurate and widely used sensors. In this paper, we report, to the best of our knowledge, for the first time a comparison between these two sensors in an annular air–oil flow. Simulations were accomplished with benchmarked COMSOL Multiphysics software and MCNPX code. Results show that the general sensitivity of gamma-ray sensor is ~ 90% higher than the general sensitivity of capacitance-based sensor. For a more accurate comparison, momentary sensitivity factors for a variety void fractions in both sensors were obtained. In the low void fraction range, the gamma-ray sensor has much better performance; however, in the high void fraction range, the capacitance-based sensor has a better performance. In the range of 0.9–1 void fractions, the momentary sensitivity of capacitance-based sensor is ~ 67% higher than that of gamma-ray attenuation-based sensor.

CEA-JSI Experimental Benchmark for validation of the modeling of neutron and gamma-ray detection instrumentation used in the JSI TRIGA reactor

Constant improvements of the computational power and methods as well as demands of accurate and reliable measurements for reactor operation and safety require a continuous upgrade of the instrumentation. In particular, nuclear sensors used in nuclear fission reactors (research or power reactors) or in nuclear fusion facilities are operated under intense mixed neutron and gamma-ray fields, and need to be calibrated and modeled to provide selective and accurate neutron and gamma-ray measurements. The French Atomic Energy and Alternative Energies Commission (CEA) and the Jožef Stefan Institute (JSI) have started an experimental program dedicated to a detailed experimental benchmark with analysis using Monte Carlo particle transport calculations and a series of neutron and gamma-ray sensor types used in the JSI TRIGA Mark II reactor. CEA has setup a simplified TRIPOLI-4® modeling scheme of the JSI TRIGA reactor based on the information available in the IRPhEP benchmark in order to facilitate analysis of future neutron and gamma-ray measurements. These allow the CEA to perform a TRIPOLI-4 instrumentation calculation scheme benchmarked with the JSI MCNP model. This paper presents the main results of this CEA calculation scheme application and the analysis of their comparison to the JSI results obtained in 2012 with the MCNP5 & ENDF/B-VII.0 calculation scheme. This paper will conclude with some information about the new experimental program to be carried out in 2022 in the TRIGA reactor core.

The First Terrestrial Electron Beam Observed by the Atmosphere‐Space Interactions Monitor

AbstractWe report the first Terrestrial Electron Beam detected by the Atmosphere‐Space Interactions Monitor. It happened on 16 September 2018. The Atmosphere‐Space Interactions Monitor Modular X and Gamma ray Sensor recorded a 2 ms long event, with a softer spectrum than typically recorded for Terrestrial Gamma ray Flashes (TGFs). The lightning discharge associated to this event was found in the World Wide Lightning Location Network data, close to the northern footpoint of the magnetic field line that intercepts the International Space Station location. Imaging from a GOES‐R geostationary satellite shows that the source TGF was produced close to an overshooting top of a thunderstorm. Monte‐Carlo simulations were performed to reproduce the observed light curve and energy spectrum. The event can be explained by the secondary electrons and positrons produced by the TGF (i.e., the Terrestrial Electron Beam), even if about 3.5% to 10% of the detected counts may be due to direct TGF photons. A source TGF with a Gaussian angular distribution with standard deviation between 20.6° and 29.8° was found to reproduce the measurement. Assuming an isotropic angular distribution within a cone, compatible half angles are between 30.6° and 41.9°, in agreement with previous studies. The number of required photons for the source TGF could be estimated for various assumption of the source (altitude of production and angular distribution) and is estimated between 1017.2 and 1018.9 photons, that is, compatible with the current consensus.

Dosimetric investigation of a new quantum dots/nanocomposite (CdTe QDs/PVK) sensor for real-time gamma radiation detection

The design of organic/inorganic polymer nanoparticles-based hybrids is promising for gamma ray sensor systems. Here, we design semiconducting nanocomposite system for efficient gamma ray harvesting system where cadmium telluride (CdTe) quantum dots act as dopant and poly(N-vinyl carbazole) (PVK) polymer acts as host. Highly crystalline 1-dodecanethiol (1-DDT) decorated CdTe quantum dots with average diameter of ~ 3 nm were synthesized and characterized with high-resolution transmission electron microscopy (HR-TEM) analysis. Nearly monodispersed CdTe/PVK nanocomposite was subsequently prepared by addition of CdTe quantum dots (QDs) in poly(N-vinyl carbazole) matrix. The photophysical interactions between polymer host and QDs have been investigated by preparing an ohmic contact detector using a conductive cell with two gold-coated walls. Gamma detecting properties of the CdTe QDs/PVK nanocomposite such as sensitivity, repeatability, and the linearity of dose rate response were assessed. Significant enhancement in photoconductivity induced by the gamma radiation in CdTe QDs/PVK nanocomposite has been demonstrated.

Room temperature semiconductor detectors for nuclear security

Preventing radioactive sources from being used for harmful purposes is a global challenge. A requirement for solving the challenge is developing radiation detectors that are efficient, sensitive, and practical. Room temperature semiconductor detectors (RTSDs) are an important class of gamma-ray sensors because they can generate high-resolution gamma-ray spectra at ambient operating temperatures. A number of diverse and stringent requirements must be met for semiconducting materials to serve as sensors in RTSD spectrometers, which limits the number of candidates of interest that receive attention and undergo focused research and development efforts. Despite this, the development of new compounds for sensors in RTSDs is a thriving research field, and a number of materials with stunning potential as RTSD materials have emerged within the last decade. In this perspective, the state of the art in RTSD materials is examined, and emerging semiconducting compounds are reviewed. The highly developed CdTe, CdZnTe, HgI2, and TlBr are first discussed to highlight the potential that can emerge from RTSD compounds in advanced stages of technological development. Thereafter, emerging compounds are reviewed by class from chalcogenides, iodides and chalcohalides, and organic-inorganic hybrid compounds. This work provides both a compilation of the physical and electronic properties of the emerging RTSD candidates and a perspective on the importance of material properties for the future of compounds that can transform the field of radiation detection science.

Near Real-Time Measurement of Snow Water Equivalent in the Nepal Himalayas

Seasonal snow is an important component of the Himalayan hydrological system, but a lack of observations at high altitude hampers understanding and forecasting of water availability in this region. Here, we use a passive gamma ray sensor that measures snow water equivalent (SWE) and complementary meteorological instruments installed at 4962 m a.s.l. in the Nepal Himalayas to quantify the evolution of SWE and snow depth over a two year period. We assess the accuracy, spatial representativeness and the applicability of the SWE and snow depth measurements using time lapse camera imagery and field observations. The instrument setup performs well for snowpacks >50 mm SWE, but caution must be applied when interpreting measurements from discontinuous, patchy snow cover or those that contain lenses of refrozen meltwater. Over their typical ~6 month lifetime, snowpacks in this setting can attain up to 200 mm SWE, of which 10-15 % consists of mixed precipitation and rain-on-snow events. Precipitation gauges significantly underrepresent the solid fraction of precipitation received at this elevation by almost 40 % compared to the CS725. The application of sub-daily time lapse camera imagery can help to correctly interpret and increase the reliability and representativeness of snowfall measurements. Our monitoring approach provides high quality, continuous, near real time information that is essential to develop snow models in this data scarce region. We recommend that a similar instrument setup be extended into remote Himalayan environments to facilitate widespread snowpack monitoring and further our understanding of the high-altitude water cycle.

Design of a robust and compact gamma sensor: Assessment of uranium detection in underground COx mudstone for nuclear waste management

Abstract In the context of deep geological radioactive waste disposal in France, various experiments have been designed, including in situ hydrogeological tests, chemical measurements and diffusion experiments. In this paper, we focus on in situ Diffusion of Radionuclides (DRN) tests, typically for actinide diffusion. These tests involved the construction of a powerful and qualified instrument that fulfills requirements for in situ radionuclides measurements. This implied a very specific design of four channels 1x1 inch cylinder YSO gamma-ray sensors, satisfying severe geometric and operational constraints while displaying high sensitivity and robust, real time on-line performance. The calibration of such sensors was assessed regarding their ability to quantify the minimum quantity of natural uranium that could be detected with and without the presence of Callovian–Oxfordian mudstone (COx) screens. Its design, calibration,and detection sensitivity are described in the present paper. The sensor sensitivity at 12 and 6 counts/second/g(U) without and with COx screening effect were determined for energy peak counting windows (50–105 keV) respectively. This was equivalent to a limit of detection (LOD) of uranium at 42.5 mg and 126 mg without and with a 7 cm thickness of COx sample. These sensors provided the first trial for in situ actinide diffusion tests in the context of nuclear waste management.

Multi-point gamma-ray monitoring at radioprotection levels with image devices

A multi-point system for the simultaneous interrogation of several extrinsic polymer optical fiber-based gamma-ray sensors is demonstrated. As a proof of concept, four different sensing heads have been measured, all of them based on a chemically etched fiber tip plus an inorganic scintillator powder. Two inorganic scintillators have been tested, namely Terbium doped Gadolinium Oxysulfide (Tb:GADOX) and Cerium doped Yttrium-Aluminum garnet (YAG:Ce). These sensing heads are interrogated with a commercial image device (CMOS camera). Such device does not need any cooling stage, optical filters or image intensifier elements. The response for each individual transducer is inside a 2D grid-shape array image, which provides a multiplexing method scalable with the number of the desired interrogation points. The interrogation procedure takes advantage of well-stablished digital image processing techniques, which include the selection of the regions of interest (ROIs) associated to the response of each individual sensing-head, plus the suitable RGB channel selection to improve the signal to noise ratio in the final measurement. Thus, only the Green channel has been found to render useful signal for gamma ray monitoring. Furthermore, the selection of the exposure time in the CMOS camera also permits to adjust the radiation levels to be detected.All tests were run under gamma irradiation from a calibrated 137Cs source, the reference isotope for environmental protection. The obtained results show the feasibility of simultaneously interrogating several gamma ray sensors, which can provide reliable measurements to quickly detect the presence of hazardous radioactive materials in large accidental leakage scenarios.

Monte Carlo modelling of a neutron-induced gamma-ray sensor for landmine or explosive detection

Monte Carlo simulations were carried out to model a thermal neutron-induced gamma-ray sensor for anti-personnel-landmine (APM) or explosive detection. This is done by employing the thermal neutron prompt gamma activation (TNPGA) technique. The neutron capture reaction on nitrogen 14N(n,γ)15N is analyzed to detect the subsequent characteristic 10.8 MeV gamma rays. This is done by modelling a suitable geometry consisting of a point 252Cf source placed inside a sphere of lead (Pb) which is contained in a cylinder of high density polyethylene (HDPE), together with a NaI (Tl) detector. The sensor geometry was optimized and the optimal configuration was selected to scan a plastic APM buried (2–10) cm. The Monte Carlo results obtained in terms of variations of the signal-to-background ratio, indicated the feasibility of employing 14N(n,γ)15N neutron capture reaction for landmine detection and the suitability of the proposed sensor for airport explosives as well.

Study on Influence of Different Gamma-ray Energy on Images of an Industrial CT System

Gamma transmission computed tomography is a powerful imaging techniques that provide a cross-sectional view or a volumetric view of the interior of an object. Therefore, reveal structural information of an object as if it had been cut open for viewing. By utilizing the properties of gamma-ray attenuation, images were reconstructed from photon counting data by gamma-ray sensor. Information revealed on these images depends greatly on resolution of the reconstructed images. In this study, the effect of gamma-ray energy used on a portable CT images is studied. Lab sample of four different material densities were used with three different gamma-ray sources namely, Am-241, Ba-133 and Cs-137 to study the effect of energy on the reconstructed images. The best reconstructed image that describes the structure of the sample used in this study is from Ba-133 with energy of 356 keV. The results provide information on suitability of the energy used for the range of material density use in this study.