Effects Of Cosmic Rays Research Articles

Space environment simulation and analyses for the DAMPE mission

Abstract DAMPE was sent into space orbit for nearly nine years. Since its expected lifespan is only three years, DAMPE has surpassed its expected lifespan by almost six years. Due to its long stay in orbit, some of its components have met with such puzzles as the capabilities of the equipment are partially degrading. The effects of the space environment are responsible for some of its degradation. So, the knowledge of the space environment in the coming year is vital for DAMPE operation. We focus on the following factors: 1) electrons and protons trapped in Earth’s radiation belts; 2) solar proton effect; 3) cosmic ray effect; 4) atom oxygen distribution. Based on the powerful analytic software SPENVIS, some typical effects of space environments are simulated and analyzed respectively, providing supportive constraints when the task team of DAMPE decides when to lengthen the lifespan, or when to start the reentry to Earth’s atmosphere.

Impact of Cosmic Rays on Radiation Exposures and Scientific Activities at the Atacama Large Millimeter/Submillimeter Array (ALMA) Sites.

This study delves into the investigation of cosmic-ray radiation exposure levels for workers and their impact on the signal correlation subsystems at the Atacama Large Millimeter/submillimeter Array (ALMA) observatory sites. The analysis presents a detailed examination of secondary cosmic ray spectra and flux at the ALMA sites, encompassing the operational period from 2010 to the present day, with a particular focus on the consequences of extreme solar flares. In terms of radiation exposure for ALMA employees, the annual exposure at the highest site (AOS) reaches approximately 4.8 mSv. This value exceeds the exposure level of a typical nuclear fuel cycle worker or those working at high-altitude Antarctica stations. The exposure is approximately 2.7 times lower at the ALMA Operations Support Facility (OSF). Furthermore, the additional ambient dose equivalent resulting from solar events, while low for events similar to those observed since the 1950s, can reach up to approximately 1 mSv when considering more ancient solar events based on environmental archives. Our analysis includes radiation effects measurements in the Baseline Correlator at the AOS and, more generally, underscores the significance of employing accurate modeling and simulation techniques to assess the effects of galactic cosmic rays and extreme solar events on the integrated circuits utilized or planned in the ALMA correlation subsystem.

The effect of cosmic rays on the observational properties of the CGM

ABSTRACT The circumgalactic medium (CGM) contains information on the cumulative effect of galactic outflows over time, generally thought to be caused by feedback from star formation and active galactic nuclei. Observations of such outflows via absorption in CGM gas of quasar sightlines show a significant amount of cold (${\lesssim}10^4\,{\rm K}$) gas, which cosmological simulations struggle to reproduce. Here, we use the adaptive mesh refinement hydrodynamical code Ramses to investigate the effect of cosmic rays (CR) on the cold gas content of the CGM using three zoom realizations of a z = 1 star-forming galaxy with supernova mechanical feedback: one with no CR feedback (referred to as no-CR), one with a medium CR diffusion coefficient $\kappa = 10^{28} \, \rm {cm^{2}\, s^{-1}}$ (CR−κmed), and one with a high rate of diffusion of $\kappa = 3\times 10^{29} \, \rm {cm^{2}\,\, s^{-1}}$ (CR−κhigh). We find that, for CR−κmed, the effects of CRs are largely confined to the galaxy itself as CRs do not extend far into the CGM. However, for CR−κhigh, the CGM temperature is lowered and the amount of outflowing gas is boosted. Our CR simulations fall short of the observed Mg ii covering fraction, a tracer of gas at temperatures ${\lesssim}10^4\,{\rm K}$, but the CR−κhigh simulation is more in agreement with covering fractions of C iv and O vi, which trace higher temperature gas.

Effects of anomalous cosmic rays on the solar wind events in the outer heliosphere

Anomalous cosmic-rays (ACRs) are thought to be originated from the acceleration of pickup ions (PUIs) at the termination shock or interplanetary shocks, and play important role for the plasma dynamics in the outer heliosphere. Due to limited observation, the effects of ACRs on the solar wind events is not well known. Under the approximation of spherical symmetry, we have developed a three-component magneto-hydrodynamic (MHD) numerical model that contains solar wind plasma, interstellar neutral atoms and ACRs, to investigate the evolution of the solar wind within a heliocentric distance from 1 to 150 astronomical units (AU). We use the solar wind observations from the OMNI database with the time from 2010.5 to 2016.0 (decimal years) at the inner boundary, and the effect of ACRs on the propagation of the solar wind events are compared with the observations from the spacecrafts of New Horizons, Voyager 1 and 2. The results show that ACRs may decrease the speed of the solar wind shocks to some extent, and the effect is positively correlated with the diffusion coefficient; a larger diffusion coefficient leads to a more pronounced effect. Moreover, the ACRs has a dissipation effect on the shock-like solar wind structures, and may play important roles on the dynamics of solar wind in the outer heliosphere.

Effect of cosmic rays and ionizing radiation on observational ultraviolet plasma diagnostics in the circumgalactic medium

ABSTRACT The relevance of some galactic feedback mechanisms, in particular cosmic-ray (CR) feedback and the hydrogen ionizing radiation field, has been challenging to definitively describe in a galactic context, especially far outside the galaxy in the circumgalactic medium (CGM). Theoretical and observational uncertainties prevent conclusive interpretations of multiphase CGM properties derived from ultraviolet (UV) diagnostics. We conduct three-dimensional magnetohydrodynamic simulations of a section of a galactic disc with star formation and feedback, including radiative heating from stars, a UV background, and CR feedback. We utilize the temperature phases present in our simulations to generate Cloudy models to derive spatially and temporally varying synthetic UV diagnostics. We find that radiative effects without additional heating mechanisms are not able to produce synthetic diagnostics in the observed ranges. For low CR diffusivity $\kappa _{\rm {cr}}=10^{28} \rm {cm}^2 \rm {s}^{-1}$, CR streaming heating in the outflow helps our synthetic line ratios roughly match observed ranges by producing transitional temperature gas (T ∼ 105–106 K). High CR diffusivity $\kappa _{\rm {cr}}=10^{29} \rm {cm}^2 \rm {s}^{-1}$, with or without CR streaming heating, produced transitional temperature gas. The key parameter controlling the production of this gas phase remains unclear, as the different star formation history and outflow evolution itself influences these diagnostics. Our work demonstrates the use of UV plasma diagnostics to differentiate between galactic/circumgalactic feedback models.

Modeling of Cosmogenic Cr Isotopes Produced in Lunar Rocks Compared With Existing Calculations and Measurements

AbstractThe nucleosynthetic Cr isotope anomalies provides useful information to trace the source and origin of extraterrestrial samples, but it is usually influenced by high‐energy cosmic rays, and evaluating such effect of cosmic rays in lunar samples is especially important. Those cosmic radiation particles (primary particles) can react with lunar materials, creating many secondary particles. Both primary and secondary particles can produce cosmogenic nuclides on the Moon. Radiation Environment and Dose at the Moon (REDMoon) is a novel GEANT4 Monte‐Carlo model built to simulate the interactions of space particles with the lunar surface and subsurface content. Using this model, we simulate the production of cosmogenic Cr isotopes (50Cr, 52Cr, 53Cr, 54Cr) at different depths of lunar surface, and compare the contribution of different reactions generating these nuclides. The results suggest that spallation reactions are the most important process producing cosmogenic Cr isotopes. We also analyze the relationship between 53Cr/52Cr and 54Cr/52Cr predicted by our model and compare it with different Apollo samples. As previously studied, we also find an approximate linear relationship between ɛ53Cr and ɛ54Cr, where ɛ53Cr (or ɛ54Cr) is the relative deviation from the standard 53Cr/52Cr ratio (or 54Cr/52Cr ratio), normalized to 1/10,000. Furthermore, we reveal a change of this linear relationship in different depths of lunar surface. Besides, we investigate how the slopes can be influenced by exposure age and the Fe/Cr ratio. With these additional factors carefully considered, the comparison between our modeled results and the measurements is better than previous studies.

Formamide synthesis in the interstellar medium catalyzed by damaged water ice

Context. Formamide is one of the possible precursors of life because it has a bond analogous to the peptide bond. Aims. In this work, we examine the reaction pathways that lead from HCN or HNC and OH to formamide. Both HCN and HNC are present in the interstellar medium, while OH could be present in interstellar water ice, which under the effect of cosmic rays, partially decomposes into H and OH. Methods. We carried out first principles calculations. We represented the solid state either by a model of clusters or by a model of slabs that takes into account periodicity. The confrontation of these two models and with the reaction in the gas phase enabled us to find reactivity trends. Results. For HCN, the formation of the C-N bond presents an energy barrier that cannot be overcome in the interstellar medium. The presence of water ice grains does not catalyze this step. The formation of the same bond from HNC is spontaneous, even without the presence of the solid. The second step of the pathway is a transposition of H. This step requires the presence of water ice for the barrier to allow the reaction to take place in the interstellar medium. The last step is a hydrogenation of a barrier-free radical. Our work therefore concludes that the synthesis of formamide can take place in the interstellar medium through water ice, which not only catalyzes the reaction but also constitutes a reservoir of OH.

Temporal Structures in Positron Spectra and Charge-Sign Effects in Galactic Cosmic Rays.

We present the precision measurements of 11years of daily cosmic positron fluxes in the rigidity range from 1.00 to 41.9GV based on 3.4×10^{6} positrons collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The positron fluxes show distinctly different time variations from the electron fluxes at short and long timescales. A hysteresis between the electron fluxes and the positron fluxes is observed with a significance greater than 5σ at rigidities below 8.5GV. On the contrary, the positron fluxes and the proton fluxes show similar time variation. Remarkably, we found that positron fluxes are modulated more than proton fluxes with a significance greater than 5σ for rigidities below 7GV. These continuous daily positron fluxes, together with AMS daily electron, proton, and helium fluxes over an 11-year solar cycle, provide unique input to the understanding of both the charge-sign and mass dependencies of cosmic rays in the heliosphere.

Monitoring of magnetospheric parameters based on cosmic ray effects in August

Using data (uncorrected for the temperature effect) from the global network of neutron monitors (GNNM), along with data from the Yakutsk muon telescope complex and the muon hodoscope URAGAN (Moscow), we have applied a modified spectrographic global survey (SGS) method to the 2018 August event in order to split cosmic ray variations into components of primary, magnetospheric, and atmospheric origin. We obtained time variations in the 4 GV-rigidity primary particle isotropic flux and pitch-angle anisotropy, as well as in the interplanetary magnetic field (IMF) orientation. We also showed variations in the geomagnetic cutoff rigidity (GCR) in Irkutsk.
 Using the obtained data on the changes in the planetary system of GCR within a simple model of a bounded magnetosphere, we have calculated some parameters of magnetospheric current systems, namely, the ring current radius, the magnetopause current radius, and the Dst index.

Nuclear data for space exploration

Understanding the harmful effects of galactic cosmic rays (GCRs) on space exploration requires a substantial amount of nuclear data. Specifically, the interaction of energetic GCR charged particles with spacecraft materials generates secondary radiations that, through energy deposition, can harm astronauts and electronic systems. By identifying the gaps in our knowledge of the relevant nuclear data—such as interaction cross sections—and identifying ways to fill those gaps—with measurements, compilations, evaluations, dissemination, reaction modeling, sensitivity studies, and uncertainty quantification—the safety and viability of space exploration can be improved. This work surveys the state of the art in this interdisciplinary field and identifies promising collaborative research topics that have significant potential to advance our understanding of the effects of the space radiation environment on space exploration.

Effects of cosmic rays’ self-modulation on the galactic diffuse gamma-ray emission

We studied how the process of self-modulation of cosmic rays, occurring upon their penetration into dense molecular clouds, affects the total gamma-ray emission of the Galaxy. We estimated how the self-modulation modifies the emission from each individual cloud and integrate the results along the line of sight for a given area in the sky. Our calculations show that the self-modulation reduces the total intensity of gamma-ray emission below 1 GeV by about 10–30%. Even though the magnitude of the effect is not large, it still can substantially affect the background gamma-ray emission at low energies.

Monitoring of heliosphere, magnetosphere and atmosphere via cosmic ray effects in August 2018

Using data of ground-level cosmic ray measurements on the neutron monitor network, along with data of Yakutsk muon telescope complex and muon hodoscope URAGAN (Moscow) uncorrected for temperature, we used modified spectrographic global survey method for an August 2018 event to split cosmic ray variations into components of primary, magnetospheric and atmospheric origin. Time evolutions of isotropic primary flux for different rigidities, pitch-angle anisotropy of cosmic rays, interplanetary magnetic field orientation were obtained, variations in geomagnetic cut-off rigidity in Irkutsk and average-mass temperature over charged components’ measurement sites were also shown.

Monitoring Heliosphere, Magnetosphere, and Atmosphere via Cosmic Ray Effects in 2018 August

Monitoring Heliosphere, Magnetosphere, and Atmosphere via Cosmic Ray Effects in 2018 August

Recent Progress in Modeling the Macro- and Micro-Physics of Radio Jet Feedback in Galaxy Clusters

Radio jets and the lobes they inflate are common in cool-core clusters and are known to play a critical role in regulating the heating and cooling of the intracluster medium (ICM). This is an inherently multi-scale problem, and much effort has been made to understand the processes governing the inflation of lobes and their impact on the cluster, as well as the impact of the environment on the jet–ICM interaction, on both macro- and microphysical scales. The developments of new numerical techniques and improving computational resources have seen simulations of jet feedback in galaxy clusters become ever more sophisticated. This ranges from modeling ICM plasma physics processes such as the effects of magnetic fields, cosmic rays, and viscosity to including jet feedback in cosmologically evolved cluster environments in which the ICM thermal and dynamic properties are shaped by large-scale structure formation. In this review, we discuss the progress made over the last ∼decade in capturing both the macro- and microphysical processes in numerical simulations, highlighting both the current state of the field, as well as the open questions and potential ways in which these questions can be addressed in the future.

Mathematical properties of Hand Incremental Effect Additivity and other synergy theories

Synergy theories for multi‐component agent combinations use 1‐agent dose‐effect relations (DERs), known from analyzing previous 1‐agent experiments, to calculate neither‐synergy‐nor‐antagonism combination DERs. Synergy theories are widely used in pharmacology, toxicology, and radiation biology. This article analyzes mathematical properties of one important synergy theory, proposed by John Hand in a little‐known article published in 2000 and here called Hand Incremental Effect Additivity (HIEA). In 2018, Hand's approach was reinvented in a radiobiology study that inadvertently overlooked his paper. We carefully state the assumptions required for mathematically rigorous development of HIEA and other synergy theories. Under these assumptions, studying synergy/antagonism between any number of agents can be done on a single 2d plot. We show that HIEA combination DER is in general not well‐defined in that it can “blow up” at finite total dose. We also formulate necessary and sufficient conditions on 1‐agent DERs preventing such pathology. Using weighted harmonic means, we study the betweenness property of HIEA synergy theory and demonstrate that Hand's combination DER has a systematic tendency for betweenness violation. On the positive side, we introduce the concept of a strongly dominant agent and show that the presence of such an agent ensures the betweenness property. We show also that the betweenness property holds for another major synergy theory, Loewe–Berenbaum Additivity. Our emphasis in this article on synergy theories that can handle any number of agents was motivated by applications to the study of toxic effects of galactic cosmic rays on astronauts during interplanetary travel.

Effects of galactic cosmic rays and finite electrical resistivity on the Jeans instability in magnetized viscoelastic fluid

Effects of galactic cosmic rays and finite electrical resistivity on the Jeans instability in magnetized viscoelastic fluid

Effects of neutron radiation as cosmic radiation on food resources

One of the major challenges in deep space exploration are effects of cosmic rays on human body and soft error, but equally important are their effects on food resources. In this study, we focused on neutrons as the secondary particle in the deep space environment and investigated how they affect food resources. Fast neutron was irradiated by the RIKEN Accelerator-driven compact Neutron Source (RANS) on meat sample. Biochemical analysis was conducted to present concrete effects of cosmic rays on food in deep space environment. Oxidative and nitrative modifications of proteins were detected by the electrophoresis and Western blotting. The result shows that nitrative modification of tryptophan, which is an essential amino acid in protein, tended to increase with increasing neutron dose.

Temporal Structures in Electron Spectra and Charge Sign Effects in Galactic Cosmic Rays.

We present the precision measurements of 11years of daily cosmic electron fluxes in the rigidity interval from 1.00 to 41.9GV based on 2.0×10^{8} electrons collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. The electron fluxes exhibit variations on multiple timescales. Recurrent electron flux variations with periods of 27days, 13.5days, and 9days are observed. We find that the electron fluxes show distinctly different time variations from the proton fluxes. Remarkably, a hysteresis between the electron flux and the proton flux is observed with a significance of greater than 6σ at rigidities below 8.5GV. Furthermore, significant structures in the electron-proton hysteresis are observed corresponding to sharp structures in both fluxes. This continuous daily electron data provide unique input to the understanding of the charge sign dependence of cosmic rays over an 11-year solar cycle.

A simple sub-grid model for cosmic ray effects on galactic scales

ABSTRACT Many recent numerical studies have argued that cosmic rays (CRs) from supernovae (SNe) or active galactic nuclei (AGNs) could play a crucial role in galaxy formation, in particular by establishing a CR-pressure-dominated circumgalactic medium (CGM). But explicit CR-magnetohydrodynamics (CR-MHD) remains computationally expensive, and it is not clear whether those results can be applied to simulations that do not explicitly treat magnetic fields or resolved interstellar medium phase structure. We therefore present an intentionally extremely simplified ‘sub-grid’ model for CRs, which attempts to capture the key qualitative behaviors of greatest interest for those interested in simulations or semi-analytical models including some approximate CR effects on galactic (≳ kpc) scales, while imposing negligible computational overhead. The model is numerically akin to some recently developed sub-grid models for radiative feedback, and allows for a simple constant parametrization of the CR diffusivity and/or streaming speed; it allows for an arbitrary distribution of sources (proportional to black hole accretion rates or star–particle SNe rates or gas/galaxy star formation rates), and interpolates between the limits where CRs escape the galaxies with negligible losses and those where CRs lose most of their energy catastrophically before escape (relevant in e.g. starburst galaxies). The numerical equations are solved trivially alongside gravity in most codes. We compare this to explicit CR-MHD simulations and discuss where the (many) sub-grid approximations break down, and what drives the major sources of uncertainty.

The Effects of Galactic Cosmic Rays on the Central Nervous System: From Negative to Unexpectedly Positive Effects That Astronauts May Encounter.

Galactic cosmic rays (GCR) pose a serious threat to astronauts' health during deep space missions. The possible functional alterations of the central nervous system (CNS) under GCR exposure can be critical for mission success. Despite the obvious negative effects of ionizing radiation, a number of neutral or even positive effects of GCR irradiation on CNS functions were revealed in ground-based experiments with rodents and primates. This review is focused on the GCR exposure effects on emotional state and cognition, emphasizing positive effects and their potential mechanisms. We integrate these data with GCR effects on adult neurogenesis and pathological protein aggregation, forming a complete picture. We conclude that GCR exposure causes multidirectional effects on cognition, which may be associated with emotional state alterations. However, the irradiation in space-related doses either has no effect or has performance enhancing effects in solving high-level cognition tasks and tasks with a high level of motivation. We suppose the model of neurotransmission changes after irradiation, although the molecular mechanisms of this phenomenon are not fully understood.