Background Radiation Research Articles

Revisiting empirical solar energetic particle scaling relations. II. Coronal mass ejections

The space radiation environment conditions and the maximum expected coronal mass ejection (CME) speed are assessed by investigating scaling laws between the peak proton flux and fluence of solar energetic particle (SEP) events with the speed of the CMEs. We used a complete catalog of SEP events, covering the last sim 25 years of CME observations (i.e., 1997 to 2017). We calculated the peak proton fluxes and integrated event fluences for events that reached an integral energy of up to E$>$ 100 MeV. For a sample of 38 strong SEP events, we first investigated the statistical relations between the recorded peak proton fluxes ($I_ P $) and fluences ($F_ P $) at a set of integral energies of E $>$10 MeV, E$>$30 MeV, E$>$60 MeV, and E$>$100 MeV versus the projected CME speed near the Sun ($V_ CME $) obtained by the Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph (SOHO/LASCO). Based on the inferred relations, we further calculated the integrated energy dependence of both $I_ P $ and $F_ P $, assuming that they follow an inverse power law with respect to energy. By making use of simple physical assumptions, we combined our derived scaling laws to estimate the upper limits for $V_ CME $, $I_ P $, and $F_ P $ by focusing on two cases of known extreme SEP events that occurred on 23 February 1956, (GLE05) and in AD774/775, respectively. Based on the physical constraints and assumptions, several options for the upper limit $V_ CME $ associated with these events were investigated. A scaling law relating $I_ P $ and $F_ P $ to the CME speed as $V_ CME ^5$ for CMEs ranging between sim 3400-5400 km/s is consistent with values of $F_ P $ inferred for the cosmogenic nuclide event of AD774/775. At the same time, the upper CME speed that the current Sun can provide possibly falls within an upper limit of $V_ CME 5500 km/s.

Environmental Radiological Impact and Risk Assessment of Natural Radioactivity at the Heap Leach Facility of Tarkwa Goldmine, Ghana: Radiotoxicity and Public Exposure

In this study, a comprehensive investigation was conducted to determine the radioactivity levels of naturally occurring radioactive materials (NORMs) in heap pads/soil and water samples within and around the operational area of Tarkwa Gold Mine in Ghana. Gamma-ray spectrometry was used to determine the activity concentrations of 238U, 232Th, and 40K in heap pads/soil, and 226Ra, 228Th, and 40K in water samples. The average activity concentrations of 226Ra and 228Th in all water samples were below the World Health Organisation (WHO) recommended guidelines for drinking water. Similarly, the average activity concentrations of measured radionuclides in heap pads/soil samples taken from depths of 0–20 cm and 20–50 cm were found to be below the worldwide average reported values. The annual effective dose to the public was estimated to be around 0.16 mSv, which is below the recommended limit. The values of the hazard indices are also below the recommended limits, implying that if heap pads/soils are used for building purposes and construction, they will not pose any significant radiation hazard. The results of this study indicate that radiation levels are within the natural background radiation levels reported in the literature and are consistent with findings from similar studies conducted in Ghana.

Characterization of the Core Face Irradiation Fixture at the Pennsylvania State University Breazeale Reactor

An efficient stacking method was applied to a multi-foil activation characterization of a core face fixture in Penn State’s TRIGA reactor using STAYSL PNNL software. The adjusted neutron energy spectra from the STAYSL PNNL software are in good agreement with the input MCNP models. The validated MCNP model was then used to predict the neutron energy spectrum within the core face fixture with a new lead shielding assembly in between the fixture and the core. Additional irradiation environment details such as the estimated gamma ray dose rates and sample temperatures provide a more comprehensive view of the core face fixture beyond the neutron energy spectrum, especially for more sensitive materials.

RD53 pixel chips for the ATLAS and CMS Phase-2 upgrades at HL-LHC

The Phase-2 upgrades at the High-Luminosity LHC of ATLAS and CMS experiments at CERN will require a new tracker with readout electronics operating in extremely harsh radiation environment (1 Grad), high hit rate (3.5 GHz/cm2) and high data rate readout (5 Gb/s). The RD53 collaboration is a joint effort between the ATLAS and CMS to qualify the chosen 65 nm CMOS technology in high radiation environment and develop the pixel readout chips of both experiments. After a half-scale demonstrator (RD53A) and full scale prototypes of the two ASICs (RD53B-ATLAS and RD53B-CMS), largely used by the two communities to characterize 3D and planar sensors, RD53 developed and submitted to foundry in 2023 the production chips. A general overview of the chip architecture will be described.

Photovoltaics Energy Potential in the Largest Greek Cities: Atmospheric and Urban Fabric Effects, Climatic Trends Influences and Socio-Economic Benefits

This comprehensive study explores the influence of aerosols and clouds on solar radiation in the urban environments of nine of Greece’s largest cities over the decade from 2014 to 2023. Utilizing a combination of Earth Observation data, radiative transfer models, and geographic information systems, the research undertook digital surface modeling and photovoltaic simulations. The study meticulously calculated the optimal rooftop areas for photovoltaic installation in these cities, contributing significantly to their energy adequacy and achieving a balance between daily electricity production and demand. Moreover, the research provides an in-depth analysis of energy and economic losses, while also highlighting the environmental benefits. These include a reduction in pollutant emissions and a decrease in the carbon footprint, aligning with the global shift towards local energy security and the transformation of urban areas into green, smart cities. The innovative methodology of this study, which leverages open access data, sets a strong foundation for future research in this field. It opens up possibilities for similar studies and has the potential to contribute to the creation of an updated, comprehensive solar potential map for continental Greece. This could be instrumental in climate change mitigation and adaptation strategies, thereby promoting sustainable urban development and environmental preservation.

A Multiwavelength Survey of Nearby M Dwarfs: Optical and Near-ultraviolet Flares and Activity with Contemporaneous TESS, Kepler/K2, Swift, and HST Observations

We present a comprehensive multiwavelength investigation into flares and activity in nearby M dwarf stars. We leverage the most extensive contemporaneous data set obtained through the Transiting Exoplanet Sky Survey, Kepler/K2, the Neil Gehrels Swift Observatory, and the Hubble Space Telescope, spanning the optical and near-ultraviolet (NUV) regimes. In total, we observed 213 NUV flares on 24 nearby M dwarfs, with ∼27% of them having detected optical counterparts, and found that all optical flares had NUV counterparts. We explore NUV/optical energy fractionation in M dwarf flares. Our findings reveal a slight decrease in the ratio of optical to NUV energies with increasing NUV energies, a trend in agreement with prior investigations on G–K stars’ flares at higher energies. Our analysis yields an average NUV fraction of flaring time for M0–M3 dwarfs of 2.1%, while for M4–M6 dwarfs it is 5%. We present an empirical relationship between NUV and optical flare energies and compare to predictions from radiative hydrodynamic and blackbody models. We conducted a comparison of the flare frequency distribution (FFDs) of NUV and optical flares, revealing that the FFDs of both NUV and optical flares exhibit comparable slopes across all spectral subtypes. NUV flares on stars affect the atmospheric chemistry, the radiation environment, and the overall potential to sustain life on any exoplanets they host. We find that early and mid-M dwarfs (M0–M5) have the potential to generate NUV flares capable of initiating abiogenesis.

Real-Time Water-to-Air Communication System Under Dynamic Water Surface and Strong Background Radiation

Real-Time Water-to-Air Communication System Under Dynamic Water Surface and Strong Background Radiation

A primary simulation study of scintillating fiber dosimetry for a proton minibeam

In this paper is explored the application of optical fibre-based dosimetry in the context of charged-particles MiniBeam Radiation Therapy through comprehensive simulation analyses. A FLUKA simulation of 64 Scintillating Plastic Optical Fibre array was implemented based on a prototype built in our group. The simulations indicate that the proposed system accurately reproduces the peak-and-valley pattern of minibeams. The optical photons transport inside and between fibres was also simulated, revealing that the optical crosstalk is negligible. The resilience of the detector’s electronics under secondary radiation composed of photons and neutrons was assessed. Our results suggest the electronics’ ability to withstand the expected radiation environment in clinical accelerators. This simulation-based investigation provides valuable insights into the feasibility of optical fibre-based dosimetry for MBRT. The results show the potential of using an array of thin scintillating plastic optical fibres to determine the peak–valley dose ratio, which is a key parameter to assess the efficacy of this emerging modality.

Thermal Comfort Effect of Natural Radiation: Color Factor in Industrial Safety Helmets, Human Health

This article presents the effects of helmet colors from protective clothing on the thermal protection factor under natural radiation. Thermal exposure distributions were measured using a thermal camera to determine the sun protection effectiveness of helmets under various exposure conditions. Increasing the thermal comfort of the hard hat, which is a work safety protective clothing, has become one of the biggest areas of interest of hard hat designers. Helmets protect human health by providing simple and useful protection against natural radiation rays. To identify the effect of the colors of the helmets, temperature distributions were detected using a thermal camera. White color is important for human health as it has the greatest effect on the thermal protection factor of helmets, which are protective clothing. In this study, recommendations for the engineering of hard hats, which are protective clothing with adequate thermal protection, are presented. Experimental results of white, blue and yellow colored helmets have been determined.

Advances in CMOS Image Sensors and Transistors Leveraging Stochastic Nanomagnets: A Comprehensive Review

Accurate modeling and assessment of complex Complementary Metal-Oxide Semiconductor (CMOS) imaging sensors and transistors, in conjunction with randomized nanomagnets for distributed computation in radiated environments, are crucial for the development of robust electronic systems. The effectiveness and resilience of these intricate parts to radiation exposure is the subject of this study, which is becoming more and more important in applications including space missions, power plants, and high-altitude flying. To take into account the interaction between CMOS technology and the unpredictable behavior of nanomagnets, a comprehensive durability modeling technique is required. The methodology that has been suggested evaluates the susceptibility of image detectors and transistors to malfunctions caused by radiation, such as dislocation damage, single-event upsets (SEUs), and impacts of total ionizing dose (TID). The impact of radiation on the power characteristics and operational dependability of these components is investigated using state-of-the-art modeling tools and experimental data. The findings suggest that random nanomagnets can improve distributed computing devices' resistance to radiation-induced failures. Through the provision of insights into reliability challenges and solutions for enhanced CMOS image sensors and transistors, this work advances the field of radiation-tolerant technologies. Future electronic device developers will find the suggested reliability modeling and evaluation methodology to be a useful resource for creating reliable devices that can resist harsh radioactive environments. Keywords— Reliability Modeling; CMOS Image Sensors; Radiation Environment; Advanced Technology Node; Transistor Structures; Stochastic Nanomagnets; Heterogeneous Computing; Probabilistic Inference

Effect of Ultraviolet Radiation on Properties of Ge2Sb2Te5 Phase Change Films.

With the expanding utilization of space technology, the stability of electronic components' performance in radiation environments has garnered significant attention. In this study, we prepared Ge2Sb2Te5 phase change films and memory units on silicon substrates to explore the influence of ultraviolet (UV) radiation on their characteristics. The experimental findings revealed that UV irradiation at a power density of 450 mW/cm2 decreased the amorphous resistance and thermal stability of Ge2Sb2Te5 films, impeding their multistage storage performance. Nevertheless, the amorphous state could still undergo effective transformation into a crystalline state. Furthermore, UV irradiation triggered the photoelectric effect, narrowing the band gap and causing a redshift of the Raman peak in amorphous films. Remarkably, the surface properties of Ge2Sb2Te5 films remained unchanged under irradiation. The phase change memory device based on Ge2Sb2Te5 film retained its SET-RESET conversion capability at a pulse width of 100 ns post-UV irradiation, demonstrating resilience against UV radiation. This study offers the practical insights for the application of phase change memory in space radiation environments.

MOSkin dosimetry for an ultra-high dose-rate, very high-energy electron irradiation environment at PEER

FLASH radiotherapy, which refers to the delivery of radiation at ultra-high dose-rates (UHDRs), has been demonstrated with various forms of radiation and is the subject of intense research and development recently, including the use of very high-energy electrons (VHEEs) to treat deep-seated tumors. Delivering FLASH radiotherapy in a clinical setting is expected to place high demands on real-time quality assurance and dosimetry systems. Furthermore, very high-energy electron research currently requires the transformation of existing non-medical accelerators into radiotherapy research environments. Accurate dosimetry is crucial for any such transformation. In this article, we assess the response of the MOSkin, developed by the Center for Medical Radiation Physics, which is designed for on-patient, real-time skin dose measurements during radiotherapy, and whether it exhibits dose-rate independence when exposed to 100 MeV electron beams at the Pulsed Energetic Electrons for Research (PEER) end-station. PEER utilizes the electron beam from a 100 MeV linear accelerator when it is not used as the injector for the ANSTO Australian Synchrotron. With the estimated pulse dose-rates ranging from (7.84±0.21)×105 Gy/s to (1.28±0.03)×107 Gy/s and an estimated peak bunch dose-rate of (2.55±0.06)×108 Gy/s, MOSkin measurements were verified against a scintillating screen to confirm that the MOSkin responds proportionally to the charge delivered and, therefore, exhibits dose-rate independence in this irradiation environment.

Confined Z-Pinch Magnetic Nozzle : A New Approach to Space Propulsion System that Utilizes Trapped Charged Particles

This paper provides a theoretical overview of a Z-pinch magnetic nozzle plasma propulsion system designed for Low Earth Orbit (LEO). The system utilizes trapped charged particles from the spacecraft's environment and magnetic confinement to generate thrust, reducing the need for onboard propellants. By employing a magnetic mirror configuration, the plasma is confined and accelerated to create propulsion. The proposed propulsion system is tailored to function in the dynamic space radiation environment of LEO, particularly in polar orbits, accounting for variations in solar activity that affect trapped protons and electrons. The mechanism involves converting magnetic plasma energy into directed kinetic energy, facilitating efficient plasma detachment and momentum transfer to the spacecraft. This study examines the feasibility, design overview, and constraints of implementing this propulsion technology. Key challenges include the variability of the space environment, technological complexities, radiation effects, plasma detachment efficiency, energy requirements, and material durability. Overcoming these challenges through innovative engineering and rigorous testing is essential for successful implementation. The Z-pinch magnetic nozzle plasma propulsion system promises to advance space propulsion technology, offering a more efficient and cost-effective method for satellite operations in LEO. With further research and development, it has the potential to support future satellite missions and space exploration initiatives.

Design of stochastic computational Levenberg Marquardt backpropagation-based technique to investigate temperature distribution of longitudinal moving porous fin

The improvement of thermal exchange is of utmost interest in a wide range of engineering areas. The current study focuses on thermal evaluation involving natural radiation and convection in a fractionally arranged moving longitudinal fin model placed under a magnetic field. We implement the Levenberg Marquardt backpropagation (LMB) algorithm for investigating an innovative use of stochastic numerical computation for analyzing the efficiency of the temperature distribution in a porous moving longitudinal fin. The datasets for LMB have been created using a shooting approach for dynamic systems with varying ranges of different parameters. The validation, testing, and training processes are used to simulate networks using the LMB approach for diverse scenarios of moving porous fin models. The reliability of results is assessed based on the regression measures, absolute error, error histograms, mean square error, and other metrics for fuller numerical modeling of the suggested LMB to investigate the thermal efficiency and effectiveness of porous moving fin.

Dark matter and its candidate particles

Theoretically predicted unseen matter called dark matter may be present in the universe. Even though it might be the primary component of cosmic matter, it is not a part of any known material that makes up a visible celestial body. Despite the fact that dark matter has not yet been directly observed, there is a wealth of evidence to support its existence, for example, through the autobiographical curve of the Milky Way, the mass distribution of galaxy clusters, the background radiation of the universe microwaves, and the formation of large-scale structures of the universe. Although great progress has been made in cosmic observation, we are still unable to determine what the constituent particles of dark matter are.There are the following speculations about what particles dark matter is composed of: baryon dark matter, such as MACHOs, rogue planets, and other possibilities; Non-baryonic dark matter: Weakly Interacting Massive Particles (WIMPs); Axion; Neutrino, etc.

Calibration HPGe detector using IAEA-U source for CBRNe

Detecting and preventing the illicit movement of radioactive materials within a country is crucial, requiring the identification of radiologic anomalies against the normal radiation background. High-purity germanium (HPGe) detectors, known for their precision and sensitivity, have become popular for analyzing radioactive materials in CBRNe scenarios. This study focused on calibrating an HPGe detector for CBRNe applications, using gamma-ray spectra from an IAEA-U reference source. Energy calibration involved identifying peaks in the spectra and creating a calibration curve for energy and channel number data. Efficiency calibration, determined using the known activity of the source, revealed a linear relationship between energy and detector response. Over four years, systematic efficiency calibrations showed a deviation of only 3% well below the recommended limit of 5%. These findings underscore the reliability of the system as a reference spectrometry method for accurate detection of radioactive materials. Graphical abstract

Numerical study and experimental validation of heat transfer capacity of flat-type divertor for fusion reactor

The divertor must simultaneously withstand unprecedented high heat fluxes of up to 20 MW/m2 and high-energy neutron irradiation of 14-MeV during fusion reactor operation. Accordingly, it is necessary to simultaneously meet the excellent heat dissipation capacity of the divertor and maintain good material performance in harsh neutron irradiation environments. The flat-type divertor demonstrates better heat transfer performance compared to monoblock divertor. Nevertheless, under the condition of a heat flux of 20 MW/m2, the heat transfer and thermal fatigue performance of flat-type divertor using advanced materials are still unidentified. In this study, we conducted a thorough analysis of the heat transfer capabilities and thermal fatigue characteristics of potassium-doped tungsten (KW)/Cu/Oxide dispersion strengthened copper (ODS-Cu)/reduced activation ferritic/martensitic (RAFM) divertor mockup adopts hypervaportron (HV) structure by numerical simulations combined with experiments. The numerical results indicate that the flat-type KW/Cu/ODS-Cu/RAFM divertor mockup expresses excellent heat transfer capacity. The contact area between the edge of the fins and the bottom surface of the ODS-Cu heat sink induces a significant increase in water flow velocity to ∼15 m/s. The peak temperature of loaded KW surface is only ∼985 °C under the flow rate of 5 t/h and inlet temperature of 20 °C. During the high heat flux tests, the prepared flat-type divertor mockup successful endured 1000 cycles of 20 MW/m2 with the peak temperature of 883 °C, and the surface temperature experienced a fluctuation of 2.4 % during the thermal fatigue tests. This study can provide a strong data reference and technical support for the development of fusion reactors, and is of great significance in advancing the commercialization of fusion energy.

Study on Single Event Effects of Enhanced GaN HEMT Devices under Various Conditions

GaN HEMT devices are sensitive to the single event effect (SEE) caused by heavy ions, and their reliability affects the safe use of space equipment. In this work, a Ge ion (LET = 37 MeV·cm2/mg) and Bi ion (LET = 98 MeV·cm2/mg) were used to irradiate Cascode GaN power devices by heavy ion accelerator experimental device. The differences of SEE under three conditions: pre-applied electrical stress, different LET values, and gate voltages are studied, and the related damage mechanism is discussed. The experimental results show that the pre-application of electrical stress before radiation leads to an electron de-trapping effect, generating defects within the GaN device. These defects will assist in charge collection so that the drain leakage current of the device will be enhanced. The higher the LET value, the more electron–hole pairs are ionized. Therefore, the charge collected by the drain increases, and the burn-out voltage advances. In the off state, the more negative the gate voltage, the higher the drain voltage of the GaN HEMT device, and the more serious the back-channel effect. This study provides an important theoretical basis for the reliability of GaN power devices in radiation environments.

Machine-learning-aided prediction of cancer attributed mortality using natural radiation, major air pollutants, and temperature as influencing variables

Machine-learning-aided prediction of cancer attributed mortality using natural radiation, major air pollutants, and temperature as influencing variables

External Radiation Dose to the Shore Crab of Chinnavilai, a High Background Natural Radiation Area

The aim of the study was to determine the activity concentration and radiation dose of radionuclides 226Ra, 228Ra & 40K in shore crab Hemigrapsus Sanguineus, in Chinnavilai, Kayakumari district, Tamil Nadu, India. Gamma spectrometry is used for determine activity concentration and radiation dose of radionuclides (226Ra, 228Ra & 40K.). The total dose values due to both internal and external contributions by all three studied radionuclides fell between 26.51 and 53.19 µGy/day. These values are far below the dose limits (10 mGy/day) prescribed for aquatic animals by the US Department of Energy (2002) and hence the animals are safe, radiologically as far as these radionuclides are concerned. The minimum internal dose for 228Ra in shore crab 0.30 and the external dose 16.42. The total dose for 228Ra in shore crab 16.72. The maximum internal dose for 228Ra in shore crab 0.64 and the external dose 30.03. The total dose for 228Ra in shore crab 30.67.