Cosmic Rays Research Articles

North Polar Spur: Gaseous plume(s) from star-forming regions ~3-5 kpc from the Galactic Center?

We argue that the North Polar Spur (NPS) and many less prominent structures are formed by gaseous metal-rich plumes associated with star-forming regions (SFRs). The SFRs located at the tangent to the 3-5 kpc rings might be particularly relevant to the NPS. A multi-temperature mixture of gaseous components and cosmic rays rises above the Galactic disk under the action of their initial momentum and buoyancy. Eventually, the plume velocity becomes equal to that of the ambient gas, which rotates with different angular speeds than the stars in the disk. As a result, the plumes acquire characteristic bent shapes. An ad hoc model of plumes' trajectories shows an interesting resemblance to the morphology of structures seen in the radio continuum and X-rays.

Using single-sample networks and genetic algorithms to identify radiation-responsive genes in rice affected by heavy ions of the galactic cosmic radiation with different LET values

IntroductionHeavy ions of the galactic cosmic radiation dominate the radiation risks and biological effects for plants under spaceflight conditions. However, the biological effects and sensitive genes caused by heavy ions with different linear energy transfer (LET) values have not been thoroughly studied.MethodsTo comprehensively analyze the biological effects of heavy ions with different LET values on rice under spaceflight conditions, we utilized the Shijian-10 recoverable satellite (SJ-10) to transport the dehydrated rice seeds on a 12.5-day mission in a 252 km low Earth orbit (LEO), and obtained rice plants hit by individual heavy ions with LET values ranging from 18 keV/μm to 213 keV/μm. The transcriptome and methylation sequencing were conducted on above plants, and a bioinformatics pipeline based on single-sample networks (SSNs) and genetic algorithms (GA) was developed to analyze the multi-omics expression profiles in this work. Note that SSNs can depict the gene interaction patterns within a single sample. The LET regression models were constructed from both gene expression and interaction pattern perspectives respectively, and the radiation response genes that played significant roles in the models were identified. We designed a gene selection algorithm based on GA to enhance the performance of LET regression models.ResultsThe experimental results demonstrate that all our models exhibit excellent regression performance (R2 values close to 1), which indicates that both gene expressions and interaction patterns can reflect the molecular changes caused by heavy ions with different LET values. LET-related genes (genes exhibiting strong correlation with LET values) and radiation-responsive genes were identified, primarily involved in DNA damage and repair, oxidative stress, photosynthesis, nucleic acid metabolism, energy metabolism, amino acid/protein metabolism, and lipid metabolism, etc. DNA methylation plays a crucial role in responding to heavy ions stressors and regulates the aforementioned processes.DiscussionTo the best of our knowledge, this is the first study to report the multi-omics changes in plants after exposure to heavy ions with different LET values under spaceflight conditions.

ToMCCA: a Toy Monte Carlo Coalescence Afterburner

Antinuclei in our Galaxy may stem either from annihilation or decay of dark matter, or from collisions of cosmic rays with the interstellar medium, which constitute the background of indirect dark matter searches. Understanding the formation mechanism of (anti)nuclei is crucial for setting limits on their production in space. Coalescence models, which describe the formation of light nuclei from final-state interaction of nucleons, have been widely employed in high-energy collisions. In this work, we introduce ToMCCA (Toy Monte Carlo Coalescence Afterburner), which allows for detailed studies of the nuclear formation processes without the overload of general-purpose event generators. ToMCCA contains parameterizations of the multiplicity dependence of the transverse momentum distributions of protons and of the baryon-emitting source size, extracted from ALICE measurements in pp collisions at s=5-13\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s} = 5 - 13$$\\end{document} TeV, as well as of the event multiplicity distributions, taken from the EPOS event generator. ToMCCA provides predictions of the deuteron transverse momentum distributions, with agreement of ∼5%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim 5\\%$$\\end{document} with the experimental data. The results of ToMCCA show that the coalescence mechanism in pp collisions depends only on the event multiplicity, not on the collision system or its energy. This allows the model to be utilized for predictions at lower center-of-mass collision energies, which are the most relevant for the production of antinuclei from processes related to dark matter. This model can also be extended to heavier nuclei as long as the target nucleus wavefunction and its Wigner function are known.

Cosmic-Ray Flux Correlation between MCMU and JBGO Neutron Monitors

Neutron monitors (NMs) are large ground-based detectors of atmospheric secondary particles, mostly neutrons, from primary cosmic rays. Their sky direction and rigidity imply a well-defined incoming (asymptotic) direction in space. From 2015 December 16 to 2017 January 8, 6 of the 18 NM counters had been transferred from McMurdo to Jang Bogo, both in Antarctica, so data from similar detectors were recorded simultaneously at these two nearby NM stations. Autocorrelations of these NM count rates are well fit as the sum of three components: an exponential function and a cosine with a period of 1 day, both centered at zero lag, plus a constant. Fitting the cross correlation of the two count rates, the functions are no longer centered at zero lag. The best-fit cosine phase is at time lag −160.22 ± 0.12 minutes. Calculating cosmic-ray trajectories in Earth's magnetic field throughout the time interval, the mean difference in response-weighted asymptotic longitudes corresponds to time lag −169.41 ± 0.31 minutes, in close agreement with the observed lag. Thus, the cosine term is consistent with and provides a technique to cleanly measure the cosmic-ray anisotropy. In contrast, the peak term shows a time lag of –14.55 minutes, much closer to the –9.60 minutes lag in rotation due to the difference in geographic longitude. We find a similar behavior in the correlations between other pairs of stations. We propose that rapid fluctuations in the counting rate may be primarily due to cosmic-ray particles of very high energy.

Playback method for dynamic star map simulation by fusing cosmic background radiation information

In this study, a playback method for dynamic star map simulation fusing cosmic background radiation information was proposed to improve the playback speed of star maps. The image distortion effect before and after the fusion of star maps and cosmic background radiation was evaluated using peak signal-to-noise ratios. The performance of the proposed and the global catalog traversal generation algorithms without cosmic background radiation simulation capability, as well as the indicators, were experimentally compared. The results showed that the average refresh rates of the view cone filtering star map fast-generation algorithm and the fusion playback algorithm of the star map and cosmic background radiation were 74.2 and 73.7 Hz, respectively. Compared with the entire catalog traversal generation algorithm, the instantaneous stability of the single-frame star map was improved by 3.045 and 3.305 times, respectively, and the consumed time consistency was improved by 4.646 and 5.068 times, respectively.

Impact of inhomogeneous diffusion on secondary cosmic ray and antiproton local spectra

Recent γ-ray and neutrino observations seem to favor the consideration of non-uniform diffusion of cosmic rays (CRs) throughout the Galaxy.In this study, we investigate the consequences of spatially-dependent inhomogeneous propagation of CRs on the fluxes of secondary CRs and antiprotons detected at Earth. A comparison is made among different scenarios in search of potential features that may guide us toward favoring one over another in the near future. We also examine both the influence of inhomogeneous propagation in the production of secondary CRs from interactions with the gas, and the effects of this scenario on the local fluxes of antiprotons and light antinuclei produced as final products of dark matter annihilation. Our results indicate that the consideration of an inhomogeneous diffusion model could improve the compatibility of the predicted local antiproton flux with that of B, Be and Li, assuming only secondary origin of these particles. In addition, our model predicts a slightly harder local antiproton spectrum, making it more compatible with the high energy measurements of AMS-02.Finally, no significant changes are expected in the predicted local flux of antiprotons and antinuclei produced from dark matter among the different considered propagation scenarios.

Overestimation of Astrophysical Gamma-Ray Energies during Thunderstorms: Synergy of Galactic and Atmospheric Accelerators

Particle accelerators abound in space plasmas, saturating the cosmos with fully stripped nuclei and gamma rays, with energies surpassing the capabilities of human-made accelerators by orders of magnitude. Upon reaching Earth’s atmosphere, these particles trigger extensive air showers (EASs), generating millions of secondary cosmic rays of lower energies. Free electrons from EASs developing in the atmosphere are seeds for atmospheric electron accelerators. Strong atmospheric electric fields (AEFs) evolving during thunderstorms act as accelerators, amplifying the intensity of electrons many times, significantly enlarging the EAS size (number of electrons). Thus, the energy of the primary cosmic ray recovered by EAS size can be significantly overestimated. Recently discovered by high-altitude EAS arrays, PeVatron candidates (ultra–high-energy (UHE) astrophysical gamma-ray sources) must be carefully examined according to the atmospheric conditions during EAS detection. Large High Altitude Air Shower Observatory and High-Altitude Water Cherenkov Observatory arrays are located in regions of frequent thunderstorms, and an AEF’s strength can reach and surpass the critical strength to start relativistic runaway electron avalanches. A few registered UHE gamma rays from stellar sources can be registered at just this time when the AEF highly enhances the EAS size. Thunderstorm ground enhancements are copiously registered at mountain peaks of Eastern Europe, Germany, and Armenia, with energies well above the threshold energy of EAS array scintillators. Thus, the overestimation of the energy of primary particles is not an exotic process but a consequence of already well-established physical phenomena. Consequently, a report on each registered UHE gamma ray should include the recorded time and corresponding weather conditions.

Investigating cosmic rays: Determining the rate of muon

Abstract. In this article, we demonstrate the investigation process of the determination of muon rate. During our investigation, we used four Cosmic Watches to trace variation of various physical quantities that would help with our further discovery. After cleaning the data, plotting, and calculating the number of muon and the actual working time of the detectors, we were able to determine muon rate, which are 0.0890.004 Hz and 0.0820.005 Hz respectively for the left two and the right two Cosmic Watches. Then, two of the four Cosmic Watches were placed at a larger distance between each other, the new rates obtained are 0.1090.005 Hz and 0.1020.005 Hz accordingly for the left and right two detectors. The specific setup of the Cosmic Watches is included later in this paper. By doing this, we discovered the inverse relationship between the rate of muon rate and the distance between the detectors, which may indicate the direction of cosmic ray pathways.

Contrasting physical erosion rates in cratonic catchments: The Ogooué and Mbei rivers, Western Central Africa

We measured the long-term physical denudation of the Ogooué River catchment using 10Be produced in situ by cosmic rays. These measurements are averaged over 25–200 ka (average 40 ka), depending on the physical denudation rate. The denudation rate of the Ogooué River catchment is slow (38 t/km2/a, 15 m/Ma), slightly higher than in Equatorial West Africa (from Senegal to Angola, 26 t/km2/a, 10 m/Ma). Physical denudation and chemical weathering fall within the same order of magnitude. Thus, although low, there is substantial chemical weathering compared to physical denudation, that likely contributes over 30 % of the total denudation.Denudation rates are spatially variable (from 10 to 60 t/km2/a) within the large Ogooué River catchment. Over the long term, physical denudation and chemical weathering roughly match, except in the Batéké Plateaux area, because the plateaus are made up of already weathered detrital material and therefore their modern flux of solutes is very low (∼9.5 t/km2/a). The spatial distribution is similar to the one described in the work of Moquet et al. (2021) on the basis of solute fluxes, i.e. the southern part of the catchment is denuding twice as fast as the northern part. We show here that the whole picture did not vary much since 100 ka, as shown by both methods which give consistent results. Faster denudation in the southern part of the catchment may be related to more uplift than in the northern part caused by the southern African “superswell”.

Radiation characterization of SiPMs for HERD PSD

Silicon photomultipliers (SiPMs) have been used in several space-borne missions, and the radiation effect as well as the performance degradation must be a concern during space operations. SiPMs will be used as photon-electric devices of the Plastic Scintillator Detector (PSD) for the High Energy Cosmic Radiation Detection (HERD) facility, and the performance change of these SiPMs under in-orbit radiation needs to be studied to satisfy the 10 years of in-orbit operation mission. In this study, the radiation damage and annealing for potential SiPM candidates including Hamamatsu and Novel Device Laboratory series have been done. The dark current for S14160-3010PS(HM10), S14160-3015PS(HM15), and EQR1511-3030D-S(NDL15) was observed to increase by a factor of 300, 400, and 200 after exposure to an equivalent on-orbit dose of 10 years. PSD showed a significant decrease in MIP detection capability after irradiation. In addition, annealing of neutron radiation damages in SiPM at temperatures 50 °C and room temperature is studied.

Search amps up for signatures of cosmic particles in ancient minerals

Advances in imaging and data handling open new possibilities.

BEYOND EARTH: THE CHALLENGES OF PEDIATRIC PHYSIOLOGY AND GROWTH IN SPACE

As humanity expands the horizons of space exploration, understanding how microgravity and cosmic radiation affect the growth and development of children becomes paramount. Childrens physiology is distinct from adults, requiring tailored medical research and interventions for space environments. This paper examines the physiological challenges pediatricians will face in space, focusing on bone density, muscle growth, cardiovascular regulation, immune response, and radiation exposure. We emphasize the need for further research to develop countermeasures that ensure the health of young space travelers.

Correlation analysis of the long-term interplay of cosmic rays, solar activity, and solar irradiance

Abstract This study presents a comprehensive analysis of the interplay between solar irradiance variability, solar activity, and cosmic rays over an extensive period from 1950 to 2023, well beyond the scope of previous research that focused on fewer solar cycles. Besides, using a robust dataset, we investigated the correlation between solar activity, represented by sunspot numbers, and the total solar irradiance, alongside the influence of cosmic rays. In this respect, our methodology incorporated sophisticated statistical techniques, including correlation analysis and linear regression, in order to elucidate the complex relationships among these variables. We identified a strong positive correlation between solar activity and total solar irradiance r ≈ + 0.95 , together with a significant anti-correlation between solar activity and cosmic rays r ≈ − 0.72 as well as cosmic rays and total solar irradiance r ≈ − 0.67 . As a consequence, the results of this study offer new insights into the long-term solar influence on climate through cosmic rays, enhancing our understanding of the Sun-Earth dynamic over prolonged periods. Likewise, the extended time series and the analytical framework developed in this study pave the way for further research into related phenomena, including the effects of cloud cover and potential links between cosmic rays and climate change.

Molecular Dynamic Simulation of Primary Damage with Electronic Stopping in Indium Phosphide

Indium phosphide (InP) is an excellent material used in space electronic devices due to its direct band gap, high electron mobility, and high radiation resistance. Displacement damage in InP, such as vacancies, interstitials, and clusters, induced by cosmic particles can lead to the serious degradation of InP devices. In this work, the analytical bond order potential of InP is modified with the short-range repulsive potential, and the hybrid potential is verified for its reliability to simulate the atomic cascade collisions. By using molecular dynamics simulations with the modified potential, the primary damage defects evolution of InP caused by 1–10 keV primary knock-on atoms (PKAs) are studied. The effects of electronic energy loss are also considered in our research. The results show that the addition of electronic stopping loss reduces the number of point defects and weakens the damage regions. The reduction rates of point defects caused by electronic energy loss at the stable state are 32.2% and 27.4% for 10 keV In-PKA and P-PKA, respectively. In addition, the effects of electronic energy loss can lead to an extreme decline in the number of medium clusters, cause large clusters to vanish, and make the small clusters dominant damage products in InP. These findings are helpful to explain the radiation-induced damage mechanism of InP and expand the application of InP devices.

Testing the molecular cloud paradigm for ultra-high-energy gamma ray emission from the direction of SNR G106.3+2.7

Context. Supernova remnants (SNRs) are believed to be capable of accelerating cosmic rays (CRs) to PeV energies. SNR G106.3+2.7 is a prime PeVatron candidate. It is formed by a head region, where the pulsar J2229+6114 and its boomerang-shaped pulsar wind nebula are located, and a tail region containing SN ejecta. The lack of observed gamma ray emission from the two regions of this SNR has made it difficult to assess which region would be responsible for the PeV CRs. Aims. We aim to characterize the very-high-energy (VHE, 0.1–100 TeV) gamma ray emission from SNR G106.3+2.7 by determining the morphology and spectral energy distribution of the region. This is accomplished using 2565 days of data and improved reconstruction algorithms from the High Altitude Water Cherenkov (HAWC) Observatory. We also explore possible gamma ray production mechanisms for different energy ranges. Methods. Using a multi-source fitting procedure based on a maximum-likelihood estimation method, we evaluate the complex nature of this region. We determine the morphology, spectrum, and energy range for the source found in the region. Molecular cloud information is also used to create a template and evaluate the HAWC gamma ray spectral properties at ultra-high-energies (UHE, > 56 TeV). This will help probe the hadronic nature of the highest-energy emission from the region. Results. We resolve one extended source coincident with all other gamma ray observations of the region. The emission reaches above 100 TeV and its preferred log-parabola shape in the spectrum shows a flux peak in the TeV range. The molecular cloud template fit on the higher energy data reveals that the SNR’s energy budget is fully capable of producing a purely hadronic source for UHE gamma rays. Conclusions. The HAWC observatory resolves one extended source between the head and the tail of SNR G106.3+2.7 in the VHE gamma ray regime. The template fit suggests the highest energy gamma rays could come from a hadronic origin. However, the leptonic scenario, or a combination of the two, cannot be excluded at this time.

Design and Development of Energy Particle Detector on China’s Chang’e-7

Particle radiation on the Moon is influenced by a combination of galactic cosmic rays, high-energy solar particles, and secondary particles interacting on the lunar surface. When China’s Chang’e-7 lander lands at the Moon’s South Pole, it will encounter this complex radiation environment. Therefore, a payload detection technology was developed to comprehensively measure the energy spectrum, direction, and radiation effects of medium- and high-energy charged particles on the lunar surface. During the ground development phase, the payload performance was tested against the design specifications. The verification results indicate that the energy measurement ranges are 30 keV to 300 MeV for protons, 30 keV to 12 MeV for electrons, and 8 to 400 MeV/n for heavy ions. The energy resolution is 10.81% for 200 keV electrons of the system facing the lunar surface; the dose rate measurement sensitivity is 7.48 µrad(Si)/h; and the LET spectrum measurement range extends from 0.001 to 37.014 MeV/(mg/cm2). These comprehensive measurements are instrumental in establishing a lunar surface particle radiation model, enhancing the understanding of the lunar radiation environment, and supporting human lunar activities.

Heliospheric Effect on Solar Activity Parameters during MaximumPhase of Solar Cycle 24 (2012-2015)

Abstract The time series of daily data of solar activity proxies, namely the sunspot number (SSN), sunspot area (SSA), solar radio flux (F10.7), modified coronal index (MCI), solar flare index (FI), and cosmic ray intensity (CRI), were analyzed to understand the solar activity modulations and short-term periodicities therein. Rieger-type, and other short-term periods, including the solar rotational period that covers the maximum activity phase period (maximum phase of solar cycle 24). The wavelet power spectra and Periodogram of SSN, SSA, F10.7, MCI, FI, and CRI exhibited a significant short-term period. The heliospheric effects exist for a particular period (~27 days) and it is related to the solar activity phenomena. The cross-correlation coefficients and time lags between the cosmic ray intensity and solar activity parameters were estimated to be 200, 46, 281, 39, and 47 days for SSN, SSA, F10.7, MCI, and FI respectively during the time series 2012-2015 (maximum phase of solar cycle 24).

Geopolymers for Space Applications Part II: Synthesis and Physical Characterization

This Technical Note presents the continuation of the results regarding the synthesis, and physical and rheological evaluation of geopolymers for space applications. In the first part, the ability of these geopolymers to resist cosmic radiation was evaluated. This second part of the research aims to present the synthesis of the geopolymers, their physical and rheological evaluation, and the fabrication of panels for placement in nanosatellites and deployer systems. Manufacturing the 2 mm-thick geopolymer panel proved to be quite a challenge due to the nature of geopolymers. Three geopolymer formulations MKG-01, MKG-02, and MKG-03 were synthesized with an adequate balance of fluidity and malleability required to manufacture the panels. The formulations offered an open window of approximately 8 h. The mass loss in the formulations was closely related to the solid/liquid ratio of the formulation. The MKG-01 presented lower viscosity and low shear stress for handling, indicating a more homogeneous dispersion than the more viscous samples MKG-02 and MKG-03.

Martian buildings: Feasible cement/concrete for onsite sustainable construction from the structural point of view

Colonizing other planets, like Mars, marks a significant milestone in the pursuit of a multi-planetary existence. Millions of people would settle on Mars in self-sufficient bases. Colonizing Mars is a long-term mission that demands self-sufficient, secure habitats and comprehensive planning. Importing structures, such as inflatable structures, from Earth is cost-prohibitive, making the utilization of in-situ resources and onsite construction the most viable approach for preparing the required buildings. Studies have shown that it is possible to produce and craft several kinds of binders and concretes with appropriate mechanical behavior using Martian soil composition; however, determining the optimal option for onsite construction remains a challenge. This study investigates available cement/concrete options for onsite construction on Mars from a structural engineering perspective, taking into account the available resources and technologies. In this regard, the observations and data provided by Martian landers, rovers, orbiters and methods such as Viking-1 & 2, Pathfinder, Spirit, Opportunity, Curiosity, Mars Express, Ultraviolet–visible/Near-infrared reflectivity spectra and Alpha particle X-ray spectrometer were used to obtain a comprehensive and detailed investigation. Eleven types of Martian cement/concrete based on the in-situ resources, soil composition, and available technologies were compared based on the criteria and indices defined in accordance with the structural engineering point of view to select the best practical option for onsite construction. These criteria encompass factors such as mechanical behavior, Martian structural loads, raw material accessibility, available sources, energy required for production, water requirement, curing and hardening time, possibility of using 3D printers, byproduct usefulness, conditions required for hardening and curing, importation requirements from Earth, production complexity, long-term durability and behavior under galactic cosmic rays (GCRs) and solar energetic particles (SEPs). The pros and cons of each cement/concrete option are thoroughly assessed, considering the harsh conditions on Mars. Additionally, the study highlights extra considerations that are crucial for onsite construction on Mars. To determine the best practical option for onsite construction and sustainable colonization, the proposed cements/concretes were compared using multi-scale spider/radar diagrams and a quantitative point of view. This perspective was enabled by assigning weights to each criterion through expert consultation, experimental data, and literature review, ensuring that the diagrams accurately reflect the features of each concrete mix. This comprehensive investigation aims to provide valuable insights into selecting the most suitable cement/concrete for onsite construction on Mars, considering the structural engineering perspective and the long-term goal of sustainable colonization.

Origin of the spectral features observed in the cosmic-ray spectrum

Recent measurements reveal the presence of several features in the cosmic-ray (CR) spectrum. In particular, the proton and helium spectra exhibit a spectral hardening at $ GV $ and a spectral steepening at $ TV $, followed by the well-known knee-like feature at $ PV $. The spectra of heavier nuclei also harden at $ GV $, while no claim can be currently made about the presence of the $ TV $ softening, due to low statistics. In addition, the B/C ratio also exhibits a hardening at $ GeV/n $ and seems to be rather shallow at $ TeV/n We propose a possible explanation of the observed spectral features in the framework of a composite diffusion scenario and considering different classes of sources. The proposed scenario is based on two assumptions. First, in the Galactic disk, where magnetic field lines are mainly oriented along the Galactic plane, particle scattering is assumed to be very inefficient. Therefore, the transport of CRs from the disk to the halo is set by the magnetic field line random walk induced by large-scale turbulence. Second, we propose that the spectral steepening at $ TV $ is related to the typical maximum rigidity reached in the acceleration of CRs by the majority of supernova remnants, while we assume that only a fraction of sources, contributing to $ 10-20<!PCT!> $ of the CR population, can accelerate particles up to sim PV rigidities. Within this framework we show that it is possible to reproduce the proton and helium spectra from GV to multi-PV; the $p$/He ratio; the spectra of CRs from lithium to iron; the $ p $ flux and the $ p /p$ ratio; and the abundance ratios B/C, B/O, C/O, Be/C, Be/O, and Be/B. We also discuss the Be Be ratio in view of the recent AMS02 preliminary measurements.