Gamma Radiation Measurements Research Articles

Contrastive Machine Learning with Gamma Spectroscopy Data Augmentations for Detecting Shielded Radiological Material Transfers

Data analysis techniques can be powerful tools for rapidly analyzing data and extracting information that can be used in a latent space for categorizing observations between classes of data. Machine learning models that exploit learned data relationships can address a variety of nuclear nonproliferation challenges like the detection and tracking of shielded radiological material transfers. The high resource cost of manually labeling radiation spectra is a hindrance to the rapid analysis of data collected from persistent monitoring and to the adoption of supervised machine learning methods that require large volumes of curated training data. Instead, contrastive self-supervised learning on unlabeled spectra can enhance models that are built on limited labeled radiation datasets. This work demonstrates that contrastive machine learning is an effective technique for leveraging unlabeled data in detecting and characterizing nuclear material transfers demonstrated on radiation measurements collected at an Oak Ridge National Laboratory testbed, where sodium iodide detectors measure gamma radiation emitted by material transfers between the High Flux Isotope Reactor and the Radiochemical Engineering Development Center. Label-invariant data augmentations tailored for gamma radiation detection physics are used on unlabeled spectra to contrastively train an encoder, learning a complex, embedded state space with self-supervision. A linear classifier is then trained on a limited set of labeled data to distinguish transfer spectra between byproducts and tracked nuclear material using representations from the contrastively trained encoder. The optimized hyperparameter model achieves a balanced accuracy score of 80.30%. Any given model—that is, a trained encoder and classifier—shows preferential treatment for specific subclasses of transfer types. Regardless of the classifier complexity, a supervised classifier using contrastively trained representations achieves higher accuracy than using spectra when trained and tested on limited labeled data.

Unveiling highly sensitive Dy3+ doped BaMgAl10O17 phosphor’s thermoluminescence trap features and temperature dependent luminescence for solid state lighting applications

This article explores the structural, morphological, thermoluminescence, and temperature-dependent emission properties of novel Dy3+ doped BaMgAl10O17(BAM-Dy) phosphors. Structural studies reveal that the phosphor has a similar structure to β-alumina. Rod-shaped interlinked surface morphology is a notable characteristic of the BAM-Dy samples. Incorporation of Dy3+ ions lead to the formation of distinct emission peaks (485 nm, 577 nm, and 635 nm) in the PL emission spectra. The effect of dopant concentration on the light output is crucial, and the highest PL intensity is observed for 1.5 mol% of Dy3+ concentration. The potential use of BAM-Dy phosphors for Gamma radiation detection and measurement is tested through thermoluminescence studies, which reveal high sensitivity, low threshold dose values, and exceptional response to low gamma doses, making them suitable for dosimetry applications. The investigation of trap parameters provides useful information about the number of traps, trapping mechanism, and trap energies, which is essential for in-depth study of synthesized phosphors for γ dosimetry application. The study of the effect of temperature on the luminescence behaviour is crucial for the application of phosphors in the light-emitting field. The BAM-Dy samples exhibit excellent thermal stability even at 210 °C, making them suitable for use in the field of White LEDs.

Radiological assessment of both unperturbed and agricultural soils from southern Ecuador

The radiological background in soils across various areas in Southern Ecuador, such as Vilcabamba, Loja, Palanda, Catamayo, and Taquil, was studied to understand the impact of agriculture and fertilizer usage on soil radiological composition. Areas impacted by agricultural activities alongside reference areas unaffected by human intervention were chosen, encompassing comprehensive analyses including gamma and alpha radiation measurements, isotopic ratio determinations, and assessments of radioactive decay chain disequilibrium. Key radiological parameters such as the radium equivalent index, the external gamma absorbed dose rate and the external hazard index were calculated. The external gamma absorbed dose is equal or lower than 57 nGy h−1 (mean value worldwide in the Earth's crust). The remaining indexes as well as the annual dose rate are far from the limits allowed for public. Fallout due to 137Cs is negligible and below the minimum detectable activity (MDA). Ratios 238U/232Th varies from 0.55 in Catamayo to 1.11 in Taquil. These values show disequilibrium between the two radioactive chains and it is possible to assume A (238U)∼0.64 A (232Th) (excluding Taquil, value 1.11). Furthermore, the radiological composition of commonly used fertilizers, including urea, NPK, NH4NO3, KNO3 and compost, was analyzed, identifying 40K and 210Pb as significant radionuclides. Interestingly, no correlation was found between the types of fertilizers used and the radiological composition of soils. The predominance of the radiological background provided by the parent rock remains the main factor influencing soil composition. The radiological background values for 226Ra, 228Ra, and 40K were established, with a mean value of 23 ± 5 Bq kg−1, 30 ± 4 Bq kg−1, and 450 ± 80 Bq kg−1, respectively. Finally, the distribution of 210Pb in unperturbed soils suggests a higher concentration in the top layer, which is indicative of natural deposition patterns, except in areas affected by erosion such as Vilcabamba, Loja, and Catamayo.

A large and feasible national survey representative of population exposure to outdoor gamma radiation in urban areas.

Although data on outdoor gamma radiation are available for many countries, they have generally been obtained with measurements performed in undisturbed environments instead of in urban areas where most of the population lives. Only one large national survey, with on-site measurements in urban areas, has been identified worldwide, probably due to high costs (e.g., personnel and instrumentation) and difficulties in selecting measuring points. A campaign of outdoor gamma radiation measurements has been carried out in the entire Italian territory. All measurement points were selected at the infrastructures of an Italian telecommunications company as representatives of all the possible situations of outdoor exposure to gamma radiation for population in urban areas. Ten replicates of portable gamma (X) detectors carried out all the measurements. Approximately 4,000 measurements have been performed. They are distributed across 2,901 Italian municipalities, accounting for 75% of the Italian population. The national population-weighted mean of the gamma ambient dose equivalent rate (ADER) is 117 nSv h-1, and it ranges from 62 to 208 nSv h-1 and from 40 to 227 nSv h-1 for 21 regions and 107 provinces, respectively. The average variability at the municipal level, in terms of the coefficient of variation (CV) is 21%, ranging from 3 to 84%. The impact of land coverage and the distance from a building on the outdoor gamma radiation level was assessed with complementary measurements, leading to differences ranging from -40 to 50% and to 50%, respectively. A representative campaign of outdoor gamma dose rate measurements has been performed in Italy, only in urban areas, to assess the exposure effect due to outdoor gamma radiation on the population. It is the largest national campaign in urban areas worldwide, with a total of 3,876 on-site measurements. The land coverage and the distance from surrounding buildings were recognized to strongly affect outdoor gamma radiation levels, leading to high variability within small areas. The collaboration with a company that owns a network of facilities on a national territory as dense as the residing population made this survey feasible and affordable. Other countries might adopt this methodology to conduct national surveys in urban environments.

Simulation method of airborne γ radiation detector response based on the equivalent transformation

In airborne gamma radiation measurement, radiation detectors' responses are simulated using the direct simulation method. However, the number of particles recorded by the detector is significantly lower than the number of particles emitted from the radiation source. This imbalance leads to low simulation efficiency, making it challenging to achieve an acceptable level of statistical uncertainty within a limited computer time. To address this inefficiency, we have theoretically proven the equivalent transformation and utilized that to devise a fast Monte Carlo simulation method known as the equivalent transformation method. Simulation results from a large body and a large surface source demonstrate that the detector response spectrum calculated using the equivalent transformation method closely agrees with those obtained through the direct simulation method. Furthermore, the efficiency ratio for the equivalent transformation method, in comparison to the direct simulation method, stands at 2.37 × 106 and 2.67 × 106 for a large body and a large surface source, respectively. These findings solidify the validity and effectiveness of the equivalent transformation method in enhancing simulation efficiency for the research on airborne gamma radiation measurement.

Development of a Multichannel Radiometer Based on Silicon Detectors for Measurement of Alpha, Beta, and Gamma Radiation of Natural Isotopes

Development of a Multichannel Radiometer Based on Silicon Detectors for Measurement of Alpha, Beta, and Gamma Radiation of Natural Isotopes

A novel analytical method to calibrate cylindrical side-hole type sodium iodide scintillation detectors

Geometrical and absolute efficiencies play a significant role in the calibration of radioactivity measuring systems, which are regularly complicated. A novel analytical method of efficiency calibration is proposed for cylindrical side-hole type sodium iodide scintillation detectors. Cylindrical side-hole type sodium iodide scintillation detectors have a cylindrical side-hole passing perpendicularly on the sodium iodide crystal axis, which is gathered in the aluminum cover. This detector is a setup for low-level gamma radiation measurement, because of the close 4π solid angle correlated with it, this setup is convenient when low-energy radiation requires efficient detection. Also, the 4π gamma-ray counting is an established way for direct activity measurements and is remarkably well suited for radionuclides with complex gamma-ray spectra. This novel approach depends on the calculation of two primary factors, the photon path length inside the detector active material, and the solid angle, delimited by the radiation source-detector system. In addition, the attenuation of photons by the sodium iodide crystal covering substance is also included by determining the photon path length through this substance. The novel analytical approach calculates the total and geometrical efficiencies of this kind of detector. In comparison, the differences with the published data in the literature indicate that the current approach is favorable in the efficiency measurement of the cylindrical side-hole type sodium iodide scintillation detectors.

RAD01: Development of a NUMTEK RAD01 Low-Cost, Portable Digital Gamma Radiation Detector

Additive manufacturing and open-source affordable instruction provide equal opportunities. Therefore, it is possible to quickly, compactly, and cheaply make expensive, scarce, and large devices in the previous century. The Geiger-Muller tube is used for the primary sensing component proposed and incorporates digital signal processing to ensure accurate and reliable measurement of gamma radiation. The performance of the developed detector is evaluated through experimental testing and comparisons with commercially available radiation detection devices. The results demonstrate the detector's ability to provide precise and consistent measurements while remaining cost-effective. Moreover, its portability and user-friendly interface make it suitable for various applications, including environmental monitoring, nuclear safety, personal radiation exposure assessment, and, most importantly, educational purposes. This low-cost portable digital gamma radiation detector contributes to the field of radiation detection by presenting an accessible solution that addresses the financial limitations associated with conventional gamma radiation detectors.

Gamma radiation for the estimation of mineral soil water content in a boreal forest

Continuous monitoring of water quantities in different soil horizons is necessary to understand the behavior of infiltrated water in the soil. Under certain conditions, using measurements of natural ground gamma radiation can help us estimate soil water content measurements over a 100 m2 surface within a 15 cm depth. A CS725 sensor can provide up to four daily estimates of soil water content by detecting the natural emission of gamma radiation. However, in boreal forest environments, gamma radiation mitigated by the water in the thick humus layers (litter, fermented, and humic horizon) can bias the underlying mineral soil water content measurements. The objective of this research was to evaluate the accuracy of methods that incorporate variables describing the surface humus layer into calculations of the underlying mineral soil water content, by measuring the soil’s natural gamma emission with the CS725. Using raw gamma radiation values obtained by CS725 sensors deployed over various boreal soils, we tested two functions. The first one included variables describing the humus layer and the other excluded these variables (manufacturer’s method). The function that included the descriptive humus layer variables showed superior results compared to the function without. The results of this study suggest that the CS725 sensor can adequately estimate mineral soil water content within ±10% absolute of the reference water content when examined with the following humus variables: humus layer thickness, fractioned composition, bulk density, and linear gamma radiation attenuation.

Assessment of Environmental Background Gamma Radiation Variation in Minna Area of Nigeria

Radiation has been acknowledged to be responsible for deleterious conditions in living tissues. Hence, environmental background gamma radiation (BGR) measurement is crucial from an environmental and health perspective. In this study, due to the absence of comprehensive background gamma radiation data and the increasing numbers of anthropogenic activities that could increase the BGR level, such as where mining activities are active. The BGR in the Minna area of Niger State, Nigeria, was measured and analyzed in this study. In-situ measurement of the background gamma radiation level was carried out using a well-calibrated portable handheld GQ GMC-500 Plus nuclear radiation detector at an elevation of about 1.0 m above ground level. A global positioning system from Garmin (GPSmap 78s) was adopted for identifying geographical locations. A total of 1172 points were surveyed across the study area for background environmental radiation. The BGR values ranged from 0.102 to 0.147 μSv/h, with an overall mean value of 0.126 μSv/h. The average measured dose rate was more than twice the reported world average value of 0.059 μSv/h. The annual effective dose equivalent (AEDE) for the research area was calculated to be 0.221 mSv/y on average. The mean AEDE is lower than the ICRP recommended limit. This shows that the population of the Minna area is radiologically safe based on the estimated AEDE value. Similarly, the excess lifetime cancer risk (ELCR) value ranged from 0.626 × 10−3 to 0.901 × 10−3 mSv/y with a mean value of 0.774 ± 0.09 × 10−3 mSv/y. The mean value of AEDE is below the 0.24 mSv/y permissible limits as recommended by the International Commission on Radiological Protection (ICRP). The mean ELCR value exceeds the average world value of 0.29 × 10−3. Also, the mean organ dose values estimated for the whole body, liver, kidney, testes, bone marrow, ovaries, and lungs are 0.150 ± 0.02, 0.102 ± 0.01, 0.137 ± 0.02, 0.181 ± 0.02, 0.152 ± 0.02, 0.128 ± 0.02 and 0.141 ± 0.02 mSv/y respectively. The differences in the calculated mean of BGR were attributed to natural and human factors. Geological variation is a fundamental factor that influences the changes in BGR. Human activities, mining, building materials, and the use of phosphate fertilizers in agricultural practices are responsible for the differences in BGR. The ELCR implies that terrestrial gamma radiation does not pose any immediate radiological health effects on residents of the area, but there is a tendency for long-term health hazards in the future, such as cancer, due to the dose accumulated.

Background gamma radiation measurements with modified thermoluminescent dosimeters from municipal dumpsites in Lagos metropolis

Abstract Measurement of background gamma radiation was carried out in two active municipal dumpsites (Olusosun and Soluos III) in Lagos metropolis, Nigeria. This study aimed to measure absorbed dose rates (ADRs) in the air in relation to distances from the dumpsites and to evaluate the annual effective dose (AED). The measurements of background gamma radiation were carried out at two active municipal dumpsites (Olusosun and Soluos III) for 3 months during the dry season in Lagos, Nigeria, with lithium fluoride thermoluminescent dosimeters (TLDs) which were arranged in a three-dimensional setup to eliminate the angular dependency of TLD dosimeter chips for environmental measurement. The dosimeters were retrieved, analyzed, and replaced at each location every month for the mentioned period. The mean ADR at Olusosun and Soluos III was 24.53–71.88 nGyh−1 with an average value of 52.91 ± 14.41 nGyh−1 and 53.67–100.67 nGyh−1 with an average value of 74.67 ± 11.28 nGyh−1, respectively. The computed mean AED was 0.065 ± 0.018 mSv/year at Soluos III, whereas at Olusosun, it was 0.092 ± 0.014 mSv/year. It was found that the mean values of ADR and AED values at Olusosun were slightly higher than the world’s average values but decreased with varying distances away from the respective dumpsites. The people living close to these dumpsites are exposed daily to low-dose gamma radiation emanating from the dumpsites and lie within global background variations.

Radiogenic heat production in rocks from the Sabinas Basin (northeastern Mexico) determined by in situ gamma radiation measurements

Radiogenic heat production in rocks from the Sabinas Basin (northeastern Mexico) determined by in situ gamma radiation measurements

Development of a real-time mobile gamma-ray measurement system for shipboard use

Large areas must be rapidly screened to monitor radiation in marine environments. For this purpose, this study developed a mobile real-time gamma-ray measurement system for shipboard use and evaluated its performance. The system was developed to measure engine or generator cooling water by installing a canister inside the ship. The minimum detectable activity of the system is about 0.8 Bq/L for a 60 s measurement period, and real-time data transmission and remote control are possible. The system was tested in the field and is currently being installed and operated on ships in service. Such a ship-based real-time gamma-radiation measurement system is suitable for a wide range of marine radiation surveillance applications and is expected to be rapidly deployed.

Plastic scintillator detector for qualitative and quantitative measurements of gamma radiation

Plastic scintillator detector for qualitative and quantitative measurements of gamma radiation

Evolution of Casedhole Nuclear Surveillance Logging Through Time

Nuclear logging techniques have played a critical role in the evaluation and surveillance of hydrocarbon reservoirs since the introduction of the gamma ray log in 1939. This paper reviews the history of key developments in nuclear logging that led to improved methods to identify gas-oil (GOC), gas-water (GWC), and oil-water (OWC) contacts in steel-cased wells, as well as methods to identify gas, steam, and waterflood front encroachment, calculate their saturations, and recognize problems in efficient reservoir depletion. This paper will focus solely on nuclear methods used to directly identify fluids behind pipe using natural gamma radiation, neutron-induced gamma radiation, and neutron flux measurements. This includes gamma ray, spectral gamma ray, single- and dual-detector neutron measurements, pulsed-neutron capture, (), and pulsed-neutron spectroscopy (carbon/oxygen or C/O) methods. It will not cover other methods of identifying fluids behind pipe, such as borehole gravity and deep electromagnetic (EM) methods using wired pipe. It also will not cover indirect methods to infer fluid types in reservoirs, such as nuclear production logging using gamma density and pulsed-neutron measurements.

An Approach to Determine of the Formation Stages of Volcanism Using Natural Gamma-Ray Spectrometer from Geophysical Methods (Example of Gölcük Volcanism)

Gölcük Caldera is in the Isparta Angle, which is an interesting tectonic structure in Southwest Anatolia. This caldera is formed as a result of back-arc volcanism associated with the northward subduction zone of the African plate under the Eurasian Plate during the Tertiary. It attracts the attention of many researchers with its tectonic and volcanic structure. In this article, the results of in situ natural gamma radiation measurements made in the caldera are evaluated. In the study, radioactive element (Potassium (%K), Uranium (eU), and Thorium (eTh)) contents of volcanics were measured in situ with the portable gamma-ray spectrometer, which is effectively used in Geophysical Engineering. The changes in natural gamma radiation of alkaline volcanic are presented with maps. When these maps are examined, it is understood that K%, U-ppm and Th-ppm concentrations of Gölcük volcanic are higher than the world average values. The high potassium concentration draws even more attention. The high potassium content indicates that the local volcanic are ultrapotassic and contain lithospheric materials. In addition, since the radioactive element concentration will reflect the magmatic development, the volcanic stages in the region have been tried to be determined. The number of these stages was determined from the curves of the radioactive data from a purely geophysical engineering (numerical) point of view, and the study area was interpreted as consisting of three different phases. This finding is supported by the results of the articles on the aging studies of the samples taken as a result of observations. In addition to these, the ranges of radioactive elements belonging to these stages were determined.

Cold season dose rate contributions from gamma, radon, thoron or progeny in legacy mines with high natural background radiation.

In areas with high natural background radiation, underground cavities tend to have high levels of airborne radionuclides. Within mines, occupancy may involve significant exposure to airborne radionuclides like radon (222Rn), thoron (220Rn) and progeny. The Fen carbonatite complex in Norway has legacy mines going through bedrock with significantly elevated levels of uranium (238U) and especially thorium (232Th), and significant levels of their progeny 222Rn and 220Rn. There are also significantly elevated levels of gamma radiation in these mines. These mines are naturally chimney ventilated and release large volumes of air to the outdoors giving a large local outdoor impact. We placed alpha track detectors at several localities within these mines to measure airborne radionuclides and measured gamma radiation of bedrock at each locality. The bedrock within the mines shows levels up to 1900Bqkg-1 for 238U, 12000Bqkg-1 for 232Th and gamma dose rates up to 11μSvh-1. Maximum levels of airborne radionuclides were 45000Bqm-3 for 220Rn and 6900Bqm-3 for 222Rn. In addition, we measured levels of thoron progeny (TnP). In order to estimate radiation dose contribution, TnP should be assessed rather than 220Rn, but deposition-based detectors may be biased by the airflow of mine-draft. We present dose rate contributions using UNSCEAR dose conversion factors, and correcting for airflow bias, finding a combined cold season dose rate within these mines of 17-24μSvh-1. Interestingly, fractional dose rate contributions vary from 0.02 to 0.6 for gamma, 0.33 to 0.95 for radon and 0.1 to 0.25 for TnP.

Development of an online gamma radiation measurement system

Raw coal is often interspersed with rocks as well as soil fragments, so natural γ-radiation measurement is used for online detection of coal quality in the coal mining and processing production process. To solve the problems of system development, data acquisition and transmission and online calibration in online γ radiation measurement, an online γ radiation measurement system was developed based on ATMEGA8L microcontroller. The upper computer software developed with Qt realizes the functions of RS485 serial communication between the upper computer and the lower computer, online configuration of the instrument working mode, real-time display and recording of the measurement results, and recording and query of the working log. After testing, the software of the upper computer is easy to operate, friendly human-computer interaction, and can realize the required functions to meet the current requirements for the intelligence of production instruments, and the RSD of the measurement results of the system is 1.1% for long time operation, with good stability.

Gamma radiation of the street corners from South zone of Natal city, Rio Grande do Norte, Brazil

This research had the objective of studying the absorbed dose of the street corner intersections from the South zone of Natal city, Brazil. This city grew up on dune lands, on siliciclastic rocks from Barreiras Formation, these dunes are quartz-sand and have heavy mineral layers bearing uranium and thorium (monazite, xenothymeo, thorianite, ilmenite, rutile, zircon, magnetite and columbite-tantalite). Not all streets in Natal city have paving, in the part with more movement they have asphalt covering over cobblestone, in the less busy have cobblestone covering, and in the quiet streets are in natural dune sand. In situ Gamma radiation measurements were performed with three portable spectrometers model RS-230 with BGO crystal, about 1 meter above the ground. The absorbed dose ranged from 11 to 150 ƞGy/h (MG: 40; Median: 39; SD: 18). In gamma spectrometry measure, Uranium varied between 0.1 to 6.2 Eq.A. ppm (MG: 1.6; Median: 1.4; SD: 1), Thorium between 0.7 to 32 Eq.A. ppm (MG: 6; Median: 5; SD: 3.3), Potassium ranged between 0.1 to 3.9 Eq.A. % (MG: 1.2; Median: 1.2; SD: 0.7). The values ​​of the absorbed dose of external radiation measured in the studied street corners show values lower than the world average of 59 ƞGy/h, and annual effective dose is also lower than the global average value of 0.48 mSv/a. Areas with higher U-K contents correspond to areas with asphalt/cobblestone capping, while areas with higher Th contents correspond to sandy streets and dunes in protected areas. This fact denote a lower radiometric risk to the population.

Environmental Gamma Radiation Measurement, Dose Rate and Lifetime Cancer Risk Assessment in Malatya Province and its Districts

Bu çalışmada, Malatya ilinde, 15 farklı noktada, gama doz hızı ölçümleri yapılmıştır. Ölçümler, her noktada hem yerde hem de yerden 1 m yükseklikte alınmıştır. Gama doz hızı ölçümleri NaI (Tl) kristaline sahip taşınabilir bir sintilasyon sayacı kullanılarak yapılmıştır. Gama doz hızlarına (DR) ek olarak, yıllık etkin doz oranları (YEDO) ve ömür boyu kanser riski (ÖBKR) değerleri de hesaplanmıştır. Yerden 1 m yükseklikte DR, YEDO ve ÖBKR için elde edilen ortalama değerler, sırasıyla, 48,47 nGy/h, 58,18 µSv/y ve 0,2110-3 olarak hesaplanmıştır. Bu çalışmada sunulan sonuçlar, Türkiye’nin farklı bölgelerinde yapılan benzer çalışmaların sonuçları ve UNSCEAR tarafından verilen dünya ortalama değerleri ile karşılaştırılmıştır.