Cosmic Ray Intensity Research Articles

Precursory Signs of Large Forbush Decreases in Relation to Cosmic Rays Equatorial Anisotropy Variation

Forbush decreases are usually characterized by increased values of cosmic ray anisotropy. The precursory signs, i.e., pre-increases and especially pre-decreases of the cosmic ray intensity, are highly anisotropic phenomena that ordinarily forewarn of such events. Two Cosmic Ray Groups from the National and Kapodistrian University of Athens (NKUA) and the Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radiowave Propagation of the Russian Academy of Sciences (IZMIRAN) have been investigating the existence of precursory signs preceding Forbush decreases in relation to different solar phenomena, interplanetary parameters, and geomagnetic conditions. In this study, large Forbush decreases (magnitude > 5%) accompanied by geomagnetic storms (i.e., geomagnetic index Dst < −100 nT and 5 ≤ Kp-index ≤ 9) and characterized by an equatorial anisotropy 1 h before the onset of the event (Axyb, %) less than 0.8% were examined regarding precursors. In total, 50 events with the aforementioned features were selected and analyzed from the IZMIRAN’s Forbush Effects and Interplanetary Disturbances database concerning the time period from 1969 until 2023. The Ring of Stations method, which depicts the cosmic ray variations for various asymptotic longitudes in relation to time, was applied on each event. The results revealed that clear signs of pre-decreases were not present for the majority of the events. Since particularly strong events were considered, most of them still showed some precursory signs, albeit mainly weak. Despite this, the value of Axyb = 0.8% proves to be a good threshold for the manual selection of FDs with well-expressed precursors.

Space Weather Effects on Heart Rate Variations: Sex Dependence

The effects of solar activity and the accompanying space weather events on human pathological conditions, physiological parameters and other psycho-physiological disturbances have been analyzed in numerous recent investigations. Moreover, many of these studies have particularly focused on the different physical reactions humans have, according to their sex, during variations in the physical environment. In the framework of the above, this work analyses heart rate data obtained from volunteers (687 men and 534 women) from three different regions (Athens, Piraeus and Heraklion) of Greece in relation to the geophysical activity and variations of environmental factors. Dst index and Ap index data, along with cosmic ray intensity data derived from the Athens Neutron Monitor Station (A.Ne.Mo.S.), were used. The study expands from April 2011 to January 2018, covering solar cycle 24. The ANalysis Of Variance (ANOVA) and the superimposed epochs methods were used in order to examine heart rate variations depending on sex. Results revealed that women tend to be more sensitive to physical environmental changes. Statistically significant results are related to the geomagnetic activity but were not obtained for cosmic ray variations.

Correlation Cosmic Ray Intensity Based on Variation in Solar Activity and Interplanetary Plasma Parameters Using Principal Component Analysis (PCA)

Correlation Cosmic Ray Intensity Based on Variation in Solar Activity and Interplanetary Plasma Parameters Using Principal Component Analysis (PCA)

Solar Activity and Cosmic Ray Intensity Variation with Geomagnetic Activity during 1996–2022

The average features of diurnal variation have been observed to change with different phases of the solar cycle, with the variance being substantially bigger at higher energies. The events were classified on the basis of different phases of solar cycles, i.e., the minimum solar activity time period, the maximum solar activity time period, and the declining phase of solar cycle. This research looks at the observed results and the influence of solar variability on cosmic rays and the geomagnetic field from 1996 to 2022. The occasional group includes a Forbush effect decline, transitory decrease, and a ground level enhancement (GLE). The 11-year fluctuation in Galactic Cosmic Rays is also known as the long-term variation, whereas the Forbush effect reduction is known as short-term variation. We investigated the long-term change in the cosmic ray intensity and its relationship to the number of Sun spots (Rz), solar wind speed (

Study of Secondary Cosmic Rays and Astronomical X-Ray Sources using Small Stratospheric Balloons

The X-ray sources of the universe are extraterrestrial in nature which emit X-ray photons. The closest strong X-ray source is the Sun, which is followed by various compact sources such as neutron stars, black holes, the Crab pulsar, etc. In this paper, we analyze the data received from several low-cost lightweight meteorological balloon-borne missions launched by the Indian Centre for Space Physics. Our main interest is to study the variation of the vertical intensity of secondary cosmic rays, the detection of strong X-ray sources, and their spectra in the energy band of ∼10–80 keV during the complete flights. Due to the lack of an onboard pointing system, low exposure time, achieving a maximum altitude of only ∼42 km, and freely rotating the payload about its axis, we modeled the background radiation flux for the X-ray detector using physical assumptions. We also present the source detection method, observation of the pulsation of the Crab (∼33 Hz), and spectra of some sources such as the quiet Sun and the Crab pulsar.

Trends in childhood leukemia incidence in urban countries and their relation to environmental factors, including space weather.

Leukemia is the most common cancer in children. Its incidence has been increasing worldwide since 1910th, suggesting the presence of common sources of the disease, most likely related to people's lifestyle and environment. Understanding the relationship between childhood leukemia and environmental conditions is critical to preventing the disease. This discussion article examines established potentially-carcinogenic environmental factors, such as vehicle emissions and fires, alongside space weather-related parameters like cosmic rays and the geomagnetic field. To discern the primary contributor, we analyze trends and annual variations in leukemia incidence among 0-14-year-olds in the United States, Canada, Australia, and Russia from 1990 to 2018. Comparisons are drawn with the number of vehicles (representing gasoline emissions) and fire-affected land areas (indicative of fire-related pollutants), with novel data for Russia introduced for the first time. While childhood leukemia incidence is rising in all countries under study, the rate of increase in Russia is twice that of other nations, possibly due to a delayed surge in the country's vehicle fleet compared to others. This trend in Russia may offer insights into past leukemia levels in the USA, Canada, and Australia. Our findings highlight vehicular emissions as the most substantial environmental hazard for children among the factors examined. We also advocate for the consideration of potential modulation of carcinogenic effects arising from variations in cosmic ray intensity, as well as the protective role of the geomagnetic field. To support the idea, we provide examples of potential space weather effects at both local and global scales. The additional analysis includes statistical data from 49 countries and underscores the significance of the magnetic field dip in the South Atlantic Anomaly in contributing to a peak in childhood leukemia incidence in Peru, Ecuador and Chile. We emphasize the importance of collectively assessing all potentially carcinogenic factors for the successful future predictions of childhood leukemia risk in each country.

Modeling of TeV Galactic Cosmic-ray Anisotropy based on Intensity Mapping in an MHD Model Heliosphere

Cosmic rays do not arrive at the Earth uniformly. Recent experiments have consistently observed small anisotropies with amplitudes of ∼0.2% in the arrival directions of cosmic rays at TeV energies. We perform the modeling of the cosmic-ray anisotropy at TeV energies using the intensity-mapping method based on Liouville’s theorem. This work indicates unrealistically small-scale ansiotropies with <∼10° angular scales in the distribution of the cosmic-ray relative intensity at the outer boundary of the heliosphere. We would possibly need to resolve an issue that the experimental data covers ten years while the Magnetohydrodynamics (MHD) model heliosphere used in this work is only a single snapshot at a certain moment. Performing the intensity-mapping for multiple snapshots of the MHD model heliosphere and taking the average of the results would improve the results of this work.

Increase in the count rates of ground-based cosmic-ray detectors caused by the heliomagnetic disturbance on 5 November 2023

This letter presents a rare physical phenomenon associated with solar activity, manifesting in anomalies within neutron, electron, and gamma-ray fluxes in the atmosphere. Conventionally, the Earth's magnetic-field disturbances reduce cosmic-ray intensity reaching the surface. However, a temporary surge in cosmic-ray flux occurs intermittently known as the magnetospheric effect (ME). Our observations reveal that this effect predominantly induces a count rate increase in particle detectors positioned at middle latitudes on mountaintops. On November 5, 2023, a 2–3% increase in neutron monitors at mountain altitudes and up to 5% increase in thin plastic scintillators registering electrons and gamma rays was observed. This flux escalation coincided with a southward orientation of the interplanetary magnetic field. Importantly, we present, for the first time, the energy spectrum of the Magnetospheric Effect observed at two mountaintops: Aragats and Zugspitze. Simulations of low-energy proton interactions in the terrestrial atmosphere affirm the augmentation of low-energy cosmic rays. Protons, typically restricted by the geomagnetic cutoff, reached the Earth's atmosphere, generating detectable particle showers on the Earth's surface. To sum up, 1) we measure an increase in the count rate of magnetospheric origin using particle detectors located at mountain altitudes and middle latitudes; 2) for the first time, we measured the energy spectra of the particle fluxes during the magnetospheric effect with spectrometers located on Mount Aragats and Zugspitze; 3) particle flux enhancement coincides with the depletion of the horizontal component of the geomagnetic field; 4) we explain why the magnetospheric effect was observed at mountain altitudes and not at sea level.

Catalogues of Forbush Decreases for the Period of 1957 - 1967

This work presents catalogues of Forbush Deceraeses (FDs) between the periods of 1957 – 1967. Forbush Decrease is a short-time decrease in the intensity of galactic cosmic rays. Such decreases are traced to solar wind disturbances. This work aims to study the catalogues of FDs. To achieve this aim, two approaches will be adopted namely; (1) downloading and presenting the IZMIRAN FDs from their website (2) applying the automated methods of FD identification developed by Okike and Umahi (2019) to identify and present FDs. The IZMIRAN catalog which applied the global survey method, identified a total of 450 FDs while the automated generated FDs (FD1 and FD2) which applied Fourier transformation, identified 500 and 458 FDs respectively. A close study on the three catalogues, pinpointed some differences and similarities. These were attributed to the differences in their methods of identification.

Интенсивность нейтронной компоненты космических лучей и влажность воздуха

Neutron monitor data is currently corrected only for the barometric effect. We cannot, however, exclude that changes in air humidity affect the intensity of the cosmic-ray neutron component recorded by neutron monitors. In this regard, we have carried out continuous measurements of air humidity and temperature when observing variations in the cosmic ray intensity with a neutron monitor in Novosibirsk. Analysis of the results of observations of meteorological parameters and cosmic ray intensity in Novosibirsk, as well as data from the global network of neutron monitors, made it possible to identify neutron component intensity variations caused by changes in air humidity. The estimated humidity effect indicates the need to regularly take it into account in the neutron monitor data. To do this, along with atmospheric pressure, regular measurements of humidity and air temperature should be performed.

Intensity of the neutron component of cosmic rays and air humidity

Neutron monitor data is currently corrected only for the barometric effect. We cannot, however, exclude that changes in air humidity affect the intensity of the cosmic-ray neutron component recorded by neutron monitors. In this regard, we have carried out continuous measurements of air humidity and temperature when observing variations in the cosmic ray intensity with a neutron monitor in Novosibirsk. Analysis of the results of observations of meteorological parameters and cosmic ray intensity in Novosibirsk, as well as data from the global network of neutron monitors, made it possible to identify neutron component intensity variations caused by changes in air humidity. The estimated humidity effect indicates the need to regularly take it into account in the neutron monitor data. To do this, along with atmospheric pressure, regular measurements of humidity and air temperature should be performed.

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.

Forbush phenomenon and the rains in the Amazon

The increase in the intensity of solar cosmic rays is often followed by a decrease in the extra solar cosmic rays. This effect is known as Forbush reduction (Scott Ellsworth Forbush), which occurs due to the solar wind that carries the Sun's magnetic field, with (coronal mass ejection - CME) and thus, protects the earth from cosmic radiation.

Small-scale Anisotropies of Cosmic Rays from Turbulent Flow

Within the classical convection–diffusion approximation, we show that the angular distribution of cosmic rays (CRs) in a highly turbulent flow may exhibit significant small-scale anisotropies. The CR intensity angular power spectrum C ℓ is then a direct reflection of interstellar turbulence, from which one expects C ℓ ∝ ℓ −γ−1 for ℓ ≫ 1, where γ is the power-law turbulence spectral index. Observations by IceCube and HAWC at TeV energies can be explained approximately with the Kolmogorov law γ = 5/3 with a convection velocity dispersion of 20 km s−1 on the scale of 10 pc.

Spectra and anisotropy of cosmic rays during gle64

Ground-based observations of cosmic rays by the spectrographic global survey method were used to study the ground-level enhancement in cosmic ray intensity on August 24, 2002. Spectra of variations of primary cosmic rays and their anisotropy were obtained. Based on measurements from the GOES spacecraft and global network of cosmic ray stations, the differential rigidity spectra of accelerated particles in the vicinity of the Sun were calculated. The maximum rigidity to which solar particles were accelerated was estimated.

Behaviour of Cosmic Ray Intensity (CRI) with Solar Flare Index and CMEs

Behaviour of Cosmic Ray Intensity (CRI) with Solar Flare Index and CMEs

Fluctuations in the Intensity of Galactic Cosmic Rays during Perturbations of the Solar Wind in Early November 2021

Fluctuations in the Intensity of Galactic Cosmic Rays during Perturbations of the Solar Wind in Early November 2021

Cross-Correlation Analysis of Cosmic Ray Intensity with Interplanetary and Geomagnetic Parameters during Disturbed and Quiet Periods

Cross-Correlation Analysis of Cosmic Ray Intensity with Interplanetary and Geomagnetic Parameters during Disturbed and Quiet Periods

The Instantaneous Response of the Geomagnetic Field, Near-Earth IMF, and Cosmic-Ray Intensity to Solar Flares

We show using superposed epoch analysis (SEA) that the most energetic protons (>60 MeV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$>60\ ext{ MeV}$\\end{document}) in the near-Earth interplanetary magnetic field (IMF) have a peak almost immediately (less than a day) after the peak in solar-flare index (SFI), while protons greater than 10 MeV peak one day after the SFI and protons greater than 1 MeV peak two days after the SFI.The geomagnetic indices AU, -AL, PC, Ap, and -Dst peak after two to three days in SEAs after the peak in SFI. The auroral electrojet indices AU and -AL, however, have only low peaks. In particular, the response of the eastward electrojet, AU, to SFI is negligible compared to other geomagnetic indices.The SEAs of the SFI and cosmic-ray counts (CR) show that the deepest decline in the CR intensity also follows with a 2 – 3-day lag the maximum of the SFI for Solar Cycles 20 – 24. The depths of the declines are related to the SFI strength of each cycle, i.e., the average decline is about 5% for Cycles 21 and 22, but only 3% for Cycle 24. The strongest Cycle 19, however, differs from the other cycles such that it has a double-peaked decline and lasts longer than the decline of the other cycles.The double-superposed epoch analyses show that the response of IMF Bv2, which is about two days, and CR to SFI are quite simultaneous, but sometimes Bv2 may peak somewhat earlier than the decline existing in CR.

On the Correlation of Cosmic-Ray Intensity with Solar Activity and Interplanetary Parameters

On the Correlation of Cosmic-Ray Intensity with Solar Activity and Interplanetary Parameters