Cosmic Ray Shielding Research Articles

Cosmic Radiation Reliability Analysis for Aircraft Power Electronics

Cosmic Ray induced failures are a major concern for the electronic system reliability of airborne and space systems. Power system voltages on aerospace platforms are on a steady upward trend. High voltage power converters suffer from Single Event Burnout failures caused by cosmic rays. The established standards propose a scaling factor based on measured background galactic cosmic rays intensity at operating altitude to apply de-rating factors. The radiation environment in the atmosphere can be increased due to the cascading of primary solar energetic particles during solar eruptions. In this work, the altitude profile of the radiation environment is simulated using a GEANT4 Monte-Carlo code. The failure rates due to both background Galactic Cosmic Rays and Solar Energetic Particles are quantitatively evaluated. Further to the known influence of geomagnetic shielding of cosmic rays, the geographical distribution of cosmic rays at flight altitudes of 10 km are also presented. The estimated cosmic ray intensity can then be combined with experimentally measured failure rate data to predict the impact on the reliability of power converters, giving a new level of accuracy in the modeling of such failure mode in more electric aircraft applications. It is shown for the first time in the scientific literature by using experimental data and state-of-the-art models, that the solar energetic particles storms fluxes vastly exceed the recommended standard and constitute a risk for the power electronics reliability.

Climate Control of Iodine Isotopic Composition Evidenced by Argentine Entisols Records

AbstractThe long half‐life of 129I makes it useful for dating marine sediments aged 2–90 Ma. However, the lack of initial value dating hinders its application for dating terrestrial sediments. A large scatter of 129I/127I in prenuclear terrestrial samples has been reported; however, the key influencing factors remain unclear. This study presented iodine isotope data from three Argentine Entisol profiles and developed an iodine‐source model to determine the influence of the source on iodine isotopic composition. The temporal patterns demonstrated clear climate modulations in natural terrestrial iodine isotopes over the last ∼15 Kyr. The model identified rock weathering as a major source of iodine in continental sediments. Higher 129I/127I ratios at mid‐high latitudes arise from weak geomagnetic shielding of cosmic rays and thus a high production rate, implying limited meridional diffusion of atmospheric iodine. These findings reveal that environmental factors are significant for constraining the initial value of terrestrial 129I.

Cerium-Doped Oxide-Based Materials for Energy and Environmental Applications

Cerium is a rare-earth metal commonly used as a dopant in various metal oxides to enhance their performances or provide optoelectronic properties. Cerium oxide (ceria) is particularly valuable owing to its unique properties and applications in various fields, such as biomedical research, photovoltaics, and industrial catalytic processes. This review focuses on the use of cerium and ceria doping in the synthesis of SiO2 and ZnO. Studies have shown that Ce-doped SiO2 thin films exhibit luminescence properties and proton shielding capabilities, and that Ce-doped ZnO has potential applications in gas sensors. In this review, we highlight the potential for controlling the luminescence and optical characteristics of these materials via cerium doping, opening up possibilities for various technological advancements and potential applications of cosmic ray shielding in space photovoltaics.

Dissociative Recombination of Rotationally Cold OH+ and Its Implications for the Cosmic Ray Ionization Rate in Diffuse Clouds

Observations of OH+ are used to infer the interstellar cosmic ray ionization rate in diffuse atomic clouds, thereby constraining the propagation of cosmic rays through and the shielding by interstellar clouds, as well as the low energy cosmic ray spectrum. In regions where the H2-to-H number density ratio is low, dissociative recombination (DR) is the dominant destruction process for OH+ and the DR rate coefficient is important for predicting the OH+ abundance and inferring the cosmic ray ionization rate. We have experimentally studied DR of electronically and vibrationally relaxed OH+ in its lowest rotational levels, using an electron–ion merged-beams setup at the Cryogenic Storage Ring. From these measurements, we have derived a kinetic temperature rate coefficient applicable to diffuse cloud chemical models, i.e., for OH+ in its electronic, vibrational, and rotational ground level. At typical diffuse cloud temperatures, our kinetic temperature rate coefficient is a factor of ∼5 times larger than the previous experimentally derived value and a factor of ∼33 times larger than the value calculated by theory. Our combined experimental and modeling results point to a significant increase for the cosmic ray ionization rate inferred from observations of OH+ and H2O+, corresponding to a geometric mean of (6.6 ± 1.0) × 10−16 s−1, which is more than a factor of 2 larger than the previously inferred values of the cosmic ray ionization rate in diffuse atomic clouds. Combined with observations of diffuse and dense molecular clouds, these findings indicate a greater degree of cosmic ray shielding in interstellar clouds than has been previously inferred.

Shielding Cosmic Ray Muon using Copper and Aluminium Sheets Composited with Polyethylene Sheets for a Better Protection

Muons are usually among the most common secondary cosmic ray particles on Earth's surface. Muon research has confirmed their occurrence in a variety of locales. It has been claimed that cosmic radiation in general, and muons in particular, have disastrous consequences on biological things and electrical components on Earth and in space. According to medical sources, cosmic rays have been linked to many ailments affecting people and other creatures. Because of these issues, cosmic ray shielding has become a crucial component of this and comparative studies. Muons emitted by cosmic rays were detected using a muon telescope made of coaxial Geiger-Muller (GM) tubes. This experiment was carried out within the muon lab of Universiti Kebangsaan Malaysia (UKM) in Malaysia to examine how the cosmic ray muon count fluctuates with the shielding of metals (Copper (Cu) and Aluminium (Al)) and polyethylene. The measured muon count for each metal sample was statistically analysed. Using both metals as shielding in this experiment revealed that adding additional Cu and Al sheets reduced the muon count. Generally, the numbers drop as the thickness increases. The results suggest that Cu outperforms Al in shielding efficacy (19% vs 16%). Because Cu has a more significant density than Al, the correlation coefficient R2 for Cu = 0.9372 is greater than R2 for Al = 0.6593, indicating that the trend for Cu is better than the trend for Al in this experiment. To study the shielding capabilities of the two composites, Al/PE and Cu/PE, ten sheets of Polyethylene (PE) were gradually put individually between the Al and Cu sheets. The results showed that PE sheets slightly increased cosmic ray shielding.

Track Structure-Based Simulations on DNA Damage Induced by Diverse Isotopes.

Diverse isotopes such as 2H, 3He, 10Be, 11C and 14C occur in nuclear reactions in ion beam radiotherapy, in cosmic ray shielding, or are intentionally accelerated in dating techniques. However, only a few studies have specifically addressed the biological effects of diverse isotopes and were limited to energies of several MeV/u. A database of simulations with the PARTRAC biophysical tool is presented for H, He, Li, Be, B and C isotopes at energies from 0.5 GeV/u down to stopping. The doses deposited to a cell nucleus and also the yields per unit dose of single- and double-strand breaks and their clusters induced in cellular DNA are predicted to vary among diverse isotopes of the same element at energies < 1 MeV/u, especially for isotopes of H and He. The results may affect the risk estimates for astronauts in deep space missions or the models of biological effectiveness of ion beams and indicate that radiation protection in 14C or 10Be dating techniques may be based on knowledge gathered with 12C or 9Be.

The potential for a continuous 10Be record measured on ice chips from a borehole

Ice cores are excellent archives for obtaining long and continuous 10Be records. However, traditional ice core 10Be measurements required a lot of ice (0.5–1kg) and often needed to be connected to a large and costly ice core project. These reasons have been the factors limiting the number and variety of 10Be projects and data. In this paper, we show measurements of 10Be on small samples (∼45g) of continuous auger ice chips from a borehole at Little Dome C (LDC), East Antarctica. The sample preparation method for 10Be accelerator mass spectrometry (AMS) was tested and optimized using test samples (∼50g) including well-mixed surface ice chips from the LDC site, snow collected in Lund (Sweden) and frozen Milli-Q water. The results show that our small ice samples should be processed without ion exchange filtration of the melt water and cleaning the subsequent Be(OH)2 precipitate. In addition, co-precipitating Be with Fe led to more reproducible measurement currents and offer the potential for higher efficiency and precision via longer measurement time. We applied the established preparation method to measure 10Be on 76 samples of the auger ice chips. The resulting 10Be concentration record for the period from 1354 to 1950 CE agrees well with the 10Be concentration in a South Pole ice core and the global 14C production rate and thus reflects well the atmospheric production signal of 10Be. We also observed insignificant mixing among the ice chip samples during the process of drilling and retrieving the ice. Therefore, the new ice chip samples are promising for assessing the long-term changes in 10Be deposition at different ice core sites. A wide application of this novel ice chip samples will increase the variety of 10Be records which will help to improve the assessment of long-term solar and geomagnetic shielding of galactic cosmic rays.

Geomagnetic dipole moment variations for the last glacial period inferred from cosmogenic radionuclides in Greenland ice cores via disentangling the climate and production signals

The geomagnetic dipole moment (GDM) modulates the production rates of cosmogenic radionuclides via the shielding of galactic cosmic rays. Therefore, it is possible to use this linkage to reconstruct past changes in the GDM based on cosmogenic radionuclide records from natural archives such as ice cores. Here we present a GDM reconstruction based on 10Be and 36Cl data from two Greenland ice cores from 11.7 ka to 108 ka b2k (before A.D. 2000). We find that the cosmogenic radionuclide records reflect a mixture of climate and production effects that require separation to evaluate the changes in the GDM. To minimize climate-related variations on isotope data, we applied a multi-linear correction method by removing common variability between 10Be and 36Cl and climate parameters (accumulation rates, δ18O and ion data) from radionuclide records. The resulting “climate corrected” radionuclide data are converted to GDM using a theoretical production model. Comparison of “climate corrected” radionuclides based GDM reconstructions with independent paleomagnetic-derived GDM records shows a good agreement. Furthermore, the “climate correction” leads to an improved agreement with GDM reconstructions than simply using radionuclide fluxes, lending support to the validity of our correction method to isolate production rate changes from ice core radionuclide records. With this correction method, we can extend the GDM reconstructions based on the cosmogenic radionuclides in ice cores to a period when there is a strong climate signal in the data.

Galactic Cosmic Ray Shielding Using Spherical Field-Reversed Array of Superconducting Coils

A deep-space galactic cosmic ray (GCR) shield in the form of a field-reversed array of superconducting coils is investigated. Exploiting the physics of plasma confinement, the shield forms a shell of magnetic energy which protects the interior from GCR flux. It is constructed from two concentric spherical assemblies of superconducting coils, each arranged in the same manner as lines of latitude on a globe. Current is modulated through the coils such that the magnetic energy in the gap between the spheres is concentrated, while the field within the inner sphere cancels. We investigate how this configuration creates a scalable and expandable magnetic shield and test it through one iteration of maximum coil current and total number of coils over which this architecture can satisfy the integral field parameter for deflection of GCRs. Included is a numerical demonstration of this shield designed to protect the Lunar Orbital Platform-Gateway within an isotropic distribution of 100,000 iron (kinetic energy 56 GeV), resulting in a reduction of particle number density within the interior of the shield between approximately 33 and 50%. Further investigations of scalability for this and other plasma confinement architectures may offer radiation mitigation for a wide range of spacecraft.

Multifunctional Cosmic-Ray Shielding of Spacecraft with Elements of Systems Engineering Design

A systems engineering approach is applied to design and propose a solution for reducing the exposure of astronauts to galactic cosmic rays in space exploration beyond the magnetosphere of Earth. The proposed design is based on the deflection of high-energy charged cosmic particles (protons, alpha particles, electrons, etc.) by the electrostatic field created by multiplate low-energy capacitors surrounding the habitat capsule of a spacecraft. In this design, the electrical field outside the capacitors is negligibly small, which prevents the attraction of charged particles from the outer space to the spacecraft and does not affect the astronauts inside. Because the proposed shielding was designed to deflect any sort of charged particles and not to stop them, the design does not require thick and heavy materials to protect the spacecraft. In addition to active shielding by the electrostatic field of light capacitors, it is also proposed that the habitat capsule be surrounded by passive shielding “sandwichlike” multilayers of novel ultralight materials filled with hydrogen. Because of this, the proposed design is relatively lightweight, made of low-cost materials, simple to build and assemble, easily scalable to smaller or larger sizes or energy, and repeatable for double or multiple layers. In addition, a technique of using the cosmic charged particles to charge the capacitors as an additional supply of energy for the shielding system function and spacecraft operation is proposed.

Analysis of the Radiation Hazard Observed by RAD on the Surface of Mars During the September 2017 Solar Particle Event

AbstractWe report dosimetric quantities measured by the Mars Science Laboratory Radiation Assessment Detector (RAD) on the surface of Mars during the 10–12 September 2017 solar particle event. Despite 23 g/cm2 of CO2 shielding provided by the atmosphere above RAD, dose rates rose above background galactic cosmic ray levels by factors of 2 to 3 over the course of several hours and leveled off at sustained peak rates for about 12 hr before declining over the following 36 hr. As the solar particle event flux was gradually declining, a shock front reached Mars and caused a sudden drop of about 15% in instantaneous dose rates. No solar particles followed the shock arrival, and the magnetic shielding of galactic cosmic rays by the shock reduced their intensity to levels below those seen before the start of the event. This event is the largest seen to date by RAD on Mars.

Using of 53 Mn and 10 Be Cosmogenic Isotopes for Geochronology and Monitoring of Cosmic Rays in Terrestrial Rocks

The article discusses the methods of measuring the accumulation of radioactive isotopes 53Mn (with a half-life of T = 3.7 million years) and 10Be (T = 1.6 million years) in the iron-containing rocks. Knowledge of accumulation dynamics of these two isotopes would allow knowing both the time of shielding and flux of cosmic rays and also changes assessing the variations in the intensity of cosmic rays, the timing of glaciations, geological changes, and climatic processes in the world in retrospect of 0.1-10 million years. The main attendance paying to neutron - activation method of isotope analysis as low-cost both in money and time and more adapted for numerous sample processing. The advantages of isotope measurements in lunar craters are emphasized.

RELATIVE CONTRIBUTION OF THE MAGNETIC FIELD BARRIER AND SOLAR WIND SPEED IN ICME-ASSOCIATED FORBUSH DECREASES

ABSTRACT We study 50 cosmic-ray Forbush decreases (FDs) from the Oulu neutron monitor data during 1997–2005 that were associated with Earth-directed interplanetary coronal mass ejections (ICMEs). Such events are generally thought to arise due to the shielding of cosmic rays by a propagating diffusive barrier. The main processes at work are the diffusion of cosmic rays across the large-scale magnetic fields carried by the ICME and their advection by the solar wind. In an attempt to better understand the relative importance of these effects, we analyze the relationship between the FD profiles and those of the interplanetary magnetic field (B) and the solar wind speed (V sw). Over the entire duration of a given FD, we find that the FD profile is generally (anti)correlated with the B and V sw profiles. This trend holds separately for the FD main and recovery phases too. For the recovery phases, however, the FD profile is highly anti-correlated with the V sw profile, but not with the B profile. While the total duration of the FD profile is similar to that of the V sw profile, it is significantly longer than that of the B profile. Using the convection–diffusion model, a significant contribution of advection by solar wind is found during the recovery phases of the FD.

Analytical Model for Estimating the Zenith Angle Dependence of Terrestrial Cosmic Ray Fluxes.

A new model called “PHITS-based Analytical Radiation Model in the Atmosphere (PARMA) version 4.0” was developed to facilitate instantaneous estimation of not only omnidirectional but also angular differential energy spectra of cosmic ray fluxes anywhere in Earth’s atmosphere at nearly any given time. It consists of its previous version, PARMA3.0, for calculating the omnidirectional fluxes and several mathematical functions proposed in this study for expressing their zenith-angle dependences. The numerical values of the parameters used in these functions were fitted to reproduce the results of the extensive air shower simulation performed by Particle and Heavy Ion Transport code System (PHITS). The angular distributions of ground-level muons at large zenith angles were specially determined by introducing an optional function developed on the basis of experimental data. The accuracy of PARMA4.0 was closely verified using multiple sets of experimental data obtained under various global conditions. This extension enlarges the model’s applicability to more areas of research, including design of cosmic-ray detectors, muon radiography, soil moisture monitoring, and cosmic-ray shielding calculation. PARMA4.0 is available freely and is easy to use, as implemented in the open-access EXcel-based Program for Calculating Atmospheric Cosmic-ray Spectrum (EXPACS).

Simple computer code for estimating cosmic-ray shielding by oddly shaped objects

This paper describes computer code for estimating the effect on cosmogenic-nuclide production rates of arbitrarily shaped obstructions that partially or completely attenuate the cosmic ray flux incident on a sample site. This is potentially useful for cosmogenic-nuclide exposure dating of geometrically complex landforms. The code has been validated against analytical formulae applicable to objects with regular geometries. It has not yet been validated against empirical measurements of cosmogenic-nuclide concentrations in samples with the same exposure history but different shielding geometries.

Effects of shielding on the induction of 53BP1 foci and micronuclei after Fe ion exposures

High atomic number and high-energy (HZE) particles in deep space are of low abundance but substantially contribute to the biological effects of space radiation. Shielding is so far the most effective way to partially protect astronauts from these highly penetrating particles. However, simulated calculations and measurements have predicted that secondary particles resulting from the shielding of cosmic rays produce a significant fraction of the total dose and dose equivalent. In this study, we investigated the biological effects of secondary radiation with two cell types, and with cells exposed in different phases of the cell cycle, by comparing the biological effects of a 200 MeV/u iron beam with a shielded beam in which the energy of the iron ion beam was decreased from 500 MeV/u to 200 MeV/u with PMMA, polyethylene (PE), or aluminum. We found that beam shielding resulted in increased induction of 53BP1 foci and micronuclei in a cell-type-dependent manner compared with the unshielded 200 MeV/u Fe ion beam. These findings provide experimental proof that the biological effects of secondary particles resulting from the interaction between HZE particles and shielding materials should be considered in shielding design.

Eccentric dipole approximation of the geomagnetic field: Application to cosmic ray computations

A comparison of the full IGRF model of the geomagnetic field with two simplified models, the truncated IGRF and the eccentric dipole model, is performed. The simplified models were found to provide a reasonable approximation for the large scale geomagnetic field distribution. In the application of the simplified geomagnetic models to the shielding of cosmic rays in the magnetosphere as quantified via the geomagnetic cut-off rigidity, the eccentric dipole and the truncated IGRF provide a good large scale view. The use of the simplified model does not introduce any additional systematic errors at the global scale but may be a source of moderate uncertainty at the regional scale in the tropical Atlantic region. This study quantitatively validates the use of such simplified geomagnetic models when describing the shielding of cosmic rays in the magnetosphere.

Depleted Argon from Underground Sources

Argon is a powerful scintillator and an excellent medium for detection of ionization. Its high discrimination power against minimum ionization tracks, in favor of selection of nuclear recoils, makes it an attractive medium for direct detection of WIMP dark matter. However, cosmogenic 39Ar contamination in atmospheric argon limits the size of liquid argon dark matter detectors due to pile-up. The cosmic ray shielding by the earth means that Argon from deep underground is depleted in 39Ar. In Cortez Colorado a CO2 well has been discovered to contain approximately 500 ppm of argon as a contamination in the CO2. In order to produce argon for dark matter detectors we first concentrate the argon locally to 3-5% in an Ar, N2, and He mixture, from the CO2 through chromatographic gas separation. The N2 and He will be removed by continuous cryogenic distillation in the Cryogenic Distillation Column recently built at Fermilab. In this talk we will discuss the entire extraction and purification process; with emphasis on the recent commissioning and initial performance of the cryogenic distillation column purification.

On the protection of extrasolar Earth-like planets around K/M stars against galactic cosmic rays

Previous studies have shown that extrasolar Earth-like planets in close-in habitable zones around M-stars are weakly protected against galactic cosmic rays (GCRs), leading to a strongly increased particle flux to the top of the planetary atmosphere. Two main effects were held responsible for the weak shielding of such an exoplanet: (a) For a close-in planet, the planetary magnetic moment is strongly reduced by tidal locking. Therefore, such a close-in extrasolar planet is not protected by an extended magnetosphere. (b) The small orbital distance of the planet exposes it to a much denser stellar wind than that prevailing at larger orbital distances. This dense stellar wind leads to additional compression of the magnetosphere, which can further reduce the shielding efficiency against GCRs. In this work, we analyse and compare the effect of (a) and (b), showing that the stellar wind variation with orbital distance has little influence on the cosmic ray shielding. Instead, the weak shielding of M star planets can be attributed to their small magnetic moment. We further analyse how the planetary mass and composition influence the planetary magnetic moment, and thus modify the cosmic ray shielding efficiency. We show that more massive planets are not necessarily better protected against galactic cosmic rays, but that the planetary bulk composition can play an important role.

Shielding from cosmic radiation for interplanetary missions: Active and passive methods

Shielding is arguably the main countermeasure for the exposure to cosmic radiation during interplanetary exploratory missions. However, shielding of cosmic rays, both of galactic or solar origin, is problematic, because of the high energy of the charged particles involved and the nuclear fragmentation occurring in shielding materials. Although computer codes can predict the shield performance in space, there is a lack of biological and physical measurements to benchmark the codes. An attractive alternative to passive, bulk material shielding is the use of electromagnetic fields to deflect the charged particles from the spacecraft target. Active shielding concepts based on electrostatic fields, plasma, or magnetic fields have been proposed in the past years, and should be revised based on recent technological improvements. To address these issues, the European Space Agency (ESA) established a Topical Team (TT) in 2002 including European experts in the field of space radiation shielding and superconducting magnets. The TT identified a number of open research questions to be addressed, including development and testing of novel shielding materials, studies on the angular distributions of energetic solar particles, and cooling systems for magnetic lenses in space. A detailed report to the ESA will be published within a few months. A summary of the TT conclusions and recommendations will be discussed in this paper, with emphasis on active shielding using superconducting magnets.