Solar Cosmic Ray Spectrum Research Articles

Application of CORSIMA (Cosmic Ray Spectrum and Intensity in Middle Atmosphere) Model for Solar Cosmic Rays. Case Study of the Extremes GLE 05 and GLE 69

The new model CORSIMA (COsmic Ray Spectrum and Intensity in Middle Atmosphere) is presented. The spectra and intensities of solar cosmic rays (SCR) from GLE (Ground Level Enhancement) 05 on 23 February 1956 and GLE 69 on 20 January 2005 at different altitudes are calculated. For this purpose, the operational CORSIMA model is applied. In the final version of the CORSIMA program, an approximation in 6 characteristic energy intervals of the Bohr–Bethe–Bloch function is used, including the charge decrease interval. Analytical expressions for the contributions of the energy intervals are provided.
 For the first time we present a quantitative and qualitative appreciation of the impact of Solar Cosmic Rays (SCRs) from the Solar Particle Events (SPEs) on the ionosphere and middle atmosphere (30–80 km). These altitudes are above the Regener–Pfotzer maximum.
 Unlike Galactic Cosmic Rays (GCR), the differential spectra of SCR essentially vary in time. The SCR fluxes also differ from each other during the different events. The spectrum and intensity behaviour is explained considering the structure of the CORSIMA program. The calculation results are in agreement with the experimental data and show characteristic features of the propagation process for different altitudes and geomagnetic latitudes. The calculations are performed for geomagnetic latitudes 90° (cusp region). The development of this research is important for the processes and mechanisms of space weather.

Cosmic Ray Spectrum and Intensity in Middle Atmosphere (CORSIMA) model. Use and Application for Solar Cosmic Rays

The new model CORSIMA (COsmic Ray Spectrum and Intensity in Middle Atmosphere) is presented. The spectra and intensities of solar cosmic rays (SCR) from GLE (Ground Level Enhancement) 05 on 23 February 1956 and GLE 69 on 20 January 2005 at different altitudes are calculated. For this purpose, the operational CORSIMA model is applied. In the final version of the CORSIMA program, an approximation in 6 characteristic energy intervals of the Bohr-Bethe-Bloch function is used, including the charge decrease interval. Analytical expressions for the contributions of the energy intervals are provided. For the first time we present a quantitative and qualitative appreciation of the impact of Solar Cosmic Rays (SCRs) from the Solar Particle Events (SPEs) on the ionosphere and middle atmosphere (30 - 80 km). These altitudes are above the Regener – Pfotzer maximum. Unlike Galactic Cosmic Rays (GCR), the differential spectra of SCR essentially vary in time. The SCR fluxes also differ from each other during the different events. The spectrum and intensity behavior is explained considering the structure of the CORSIMA program. The calculation results are in agreement with the experimental data and show characteristic features of the propagation process for different altitudes and geomagnetic latitudes. The calculations are performed for geomagnetic latitudes 90o (cusp region). The development of this research is important for the processes and mechanisms of space weather.

GLE73 Event (October 28, 2021) in Solar Cosmic Rays

Results are presented from analyzing the GLE73 event in terms of solar cosmic rays. The GLE73 event raised the count by 2–6% at polar stations of the World Neutron Monitor Network. A direct solution to the inverse problem is found, along with and the energy spectra of solar cosmic rays at the boundary of the magnetosphere are obtained and the pitch angle distribution of the flux.

Pitch-angle anisotropy and differential rigidity spectra of cosmic rays during GLE on May 2 and 6, 1998

Using data from the worldwide network of neutron monitors (39 stations) and the method of global spectrographic survey, we have studied pitch-angle anisotropy and differential rigidity spectra of cosmic rays during the ground level enhancements on May 2 and 6, 1998. We obtained differential rigidity spectra of solar cosmic rays in these events and determined the maximum rigidities to which protons accelerated. The maximum rigidities of accelerated protons during the ground level enhancements on May 2 was ~2.4; on May 6, ~1.8 GV. The revealed bidirectional pitch-angle anisotropy indicates that Earth was in the IMF loop structure during these events.

Питч-угловая анизотропия и дифференциальные жесткостные спектры космических лучей во время GLE 2 и 6 мая 1998 г.

Using data from the worldwide network of neutron monitors (39 stations) and the method of global spectrographic survey, we have studied pitch-angle anisotropy and differential rigidity spectra of cosmic rays during the ground level enhancements on May 2 and 6, 1998. We obtained differential rigidity spectra of solar cosmic rays in these events and determined the maximum rigidities to which protons accelerated. The maximum rigidities of accelerated protons during the ground level enhancements on May 2 was ~2.4; on May 6, ~1.8 GV. The revealed bidirectional pitch-angle anisotropy indicates that Earth was in the IMF loop structure during these events.

Analysis of the solar cosmic-ray spectrum during ground-level enhancements

In this work, we analyze the spectrum of solar cosmic rays flux during ground-level enhancements using the pair of lead-free and standard neutron monitors in the South Pole station. Using both monitor data, effects due to anisotropy are considerably reduced. We assume a power-law form for the solar particle spectrum at the top of the atmosphere. The spectral index was computed during all events for which data were available, regardless of the duration or the intensity of the GLE. Seventeen events were analyzed. In this paper, we show the efficiency of the method used, as well as a clear tendency of the spectral index behavior to the ratio between the observed increases in both monitors. It is also shown that the method can be used to calculate the solar cosmic ray spectrum at any required stage of the event. Our results show that the spectral index estimation depends on the choice of the yield function. For the three yield functions used in the analysis, the spectral index changes by about 10%.

Spectra and Anisotropy of Cosmic Rays During the First GLE Event of Solar Cycle 24

By employing the method of spectrographic global survey, the spectra of protons and anisotropy of cosmic rays during the firstGround-Level Enhancement (GLE) of the intensity of cosmic rays in the solar cycle 24 onMay 17, 2012, a GLE71 event, are studied on the basis of data from ground-based observations of cosmic rays by means of the worldwide network of stations and data from spacecrafts. The rigidity spectra of cosmic rays and relative variations in the intensity of cosmic rays with rigidity 2 GV in the solarecliptic geocentric coordinate system are presented within individual periods of the event under study. It is shown that, in GLE71 periods, protons were accelerated to rigidities in the range of R ~ 2.3−2.5 GV and that the respective differential rigidity spectra of solar cosmic rays are not described by a power-law or an exponential function of the particle rigidity. During the event being considered, the Earth was in the loop-shaped structure of the interplanetary magnetic field.

The MONICA Experiment for Investigating the Ion Composition of Solar Cosmic Rays

The MONICA satellite-based experiment is described. In this experiment, fluxes of cosmic-ray ions from H to Ni are investigated near the Earth in the energy range of 10–300 MeV/nucleon. The main scientific objectives of the MONICA experiment are to measure the ion and isotope compositions and the energy spectra of solar cosmic rays for individual solar events and to study the evolution of these characteristics over time. The MONICA experiment will help to investigate the ion and isotope composition of the anomalous component of cosmic rays, galactic cosmic rays, and nuclear fluxes in the Earth’s radiation belt. Observations of ion fluxes will be carried out using the MONICA high-aperture multilayer semiconductor spectrometer–telescope installed on board a spacecraft with a low-Earth circular polar orbit at a height of approximately 600 km. This orbit will make it possible to perform the method for measuring the charge of ions with energies above 10 MeV/nucleon, which is based on the use of the Earth’s magnetic field as a particle- charge separator. The geometric factor of the instrument is 100 cm2 sr and the angular resolution is 1°.

Monitoring of solar proton events at altitudes up to 1000 km: Data from the Russian space experiments. Solar proton effects in the Earth’s ozonosphere

The paper illustrates the opportunities provided by the use of data from Russian satellite experiments (CORONAS and Universitetsky-Tatiana of Meteor series) on the measurement of fluxes and spectra of solar cosmic rays at altitudes of 370–1000 km for simulation of the ozonosphere state. The results of photochemical simulation and observational data analysis showing the influence of solar protons on polar ozonosphere and lower ionosphere in periods of solar proton events (SPE) on November 4, 2001, October 28, 2003, and January 16, 2005 are presented. It is shown that the solar proton action causes ozone depletion in the mesosphere above the polar regions. The strongest depletion (up to 70%) was caused by the SPE that occurred on October 28, 2003.

Current status of the MONICA experiment to study the ionic composition of solar cosmic rays

The current status of the MONICA experiment to study fluxes of cosmic ray ions from H to Ni in the energy range of 10–300 MeV in the vicinity of the Earth is described. The main scientific objective of the MONICA experiment is to measure the ionic and isotope compositions and energy spectra of solar cosmic rays for individual solar events, and to study the time evolution of these characteristics. The MONICA experiment will also allow us to investigate the ionic and isotope compositions of the anomalous cosmic ray component, galactic cosmic rays, and fluxes of nuclei in the Earth’s radiation belt. Ion fluxes will be observed using the MONICA large-aperture multilayer semiconductor spectrometer telescope on board a spacecraft in a circumterrestrial polar orbit with an altitude on the order of 600 km. This will enable us to measure the charges of ions with energies over 10 MeV/nucleon by using the Earth’s magnetic field as a charge separator. The geometric factor of the instrument is 100 cm2 sr; its angular resolution is 1°.

Combined mechanisms of solar cosmic ray acceleration

Spectra of solar cosmic rays on the Sun’s surface at a flare site and near Earth are modeled using the Monte Carlo method. Two of the most important mechanisms of energy accumulation by the particles are considered simultaneously: the regular acceleration of ions by the impulsive electric field of the current sheet and stochastic acceleration by the Alfvenic turbulence. This leads to substantial variations in the particle spectra in the low-energy region.

Joint acceleration mechanisms for solar cosmic rays

Using Monte Carlo method we have simulated solar cosmic ray spectra (3He, 4He, O and Fe) at the flare site and at the Earth. It is shown that besides stochastic acceleration by Alfvenic turbulence an impulsive electric field of the current sheet significantly affects the ion energy spectra at low energies. Both mechanisms could explain some peculiarities in the energy spectra of heavy ions observed in experiments onboard ACE.

Peculiarities of the energy spectra of solar cosmic rays observed in the Earth’s magnetosphere

The penetration of solar cosmic rays (SCRs) from interplanetary space into the Earth’s magneto-sphere is simulated numerically. It is shown that the SCR energy spectrum observed in the magnetosphere changes when there is an anisotropic angular distribution of SCRs in interplanetary space.

A New Version of the Neutron Monitor Based Anisotropic GLE Model: Application to GLE60

In this work we present a cosmic ray model that couples primary solar cosmic rays at the top of the Earth’s atmosphere with the secondary ones detected at ground level by neutron monitors during Ground-Level Enhancements (GLEs). The Neutron Monitor Based Anisotropic GLE Pure Power Law (NMBANGLE PPOLA) model constitutes a new version of the already existing NMBANGLE model, differing in the solar cosmic ray spectrum assumed. The total output of the model is a multi-dimensional GLE picture that reveals part of the characteristics of the big solar proton events recorded at ground level. We apply both versions of the model to the GLE of 15 April 2001 (GLE60) and compare the results.

Solar cosmic ray records in lunar rock 64455

Cosmic ray produced 10Be (half-life = 1.36 × 10 6 yr), 26Al (7.05 × 10 5 yr), and 36Cl (3.01 × 10 5 yr) were measured in a depth profile of 19 carefully-ground samples from the glass-coated lunar surface rock 64455. The solar cosmic ray (SCR) produced 26Al and 36Cl in this rock are present in high concentrations, which in combination with the low observed erosion rate, <0.5 mm/Myr, provide well defined depth profiles characterizing the SCR component of the cosmic rays. In conjunction with new experimentally determined excitation functions, the 36Cl concentrations suggest a softer solar-proton spectral shape than that derived from most previous measurements. The fact that no SCR-produced 10Be activity could be detected in 64455 is in good agreement with observations in 68815 and also indicates a softer SCR spectrum. Comparison of observed SCR profiles in 64455 with theoretical calculations indicates that the average solar-proton spectrum over the past 2 Myr (based on 26Al) has an exponential rigidity parameter ( R 0) of about 90 MV with a proton flux ( J) of 73 protons/cm 2/s·4π above 10 MeV. Over the last ∼0.5 Myr (based on 36Cl) R 0 is about 70 MV with a flux of ∼196 protons/cm 2/s·4π above 10 MeV. These SCR fluxes are consistent with most previous work.

Modeling the solar cosmic ray event of 13 December 2006 using ground level neutron monitor data

In order to understand the physics under extreme solar conditions such as those producing ground level enhancements of solar cosmic rays, it is important to use accurate and reliable models. The NM-BANGLE Model is a new cosmic ray model which couples primary solar cosmic rays at the top of the Earth’s atmosphere with the secondary ones detected at ground level by neutron monitors during GLEs. This model calculates the evolution of several GLE parameters such as the solar cosmic ray spectrum, anisotropy and particle flux distribution, revealing crucial information on the energetic particle propagation and distribution. The total output of the NM-BANGLE Model is a multi-dimensional GLE picture that gives an important contribution to revealing the characteristics of solar energetic particle events recorded at ground level. In this work, the results of the NM-BANGLE Model application to the recent GLE of 13 December 2006 are presented and discussed. Moreover, a comparison with the extreme event of 20 January 2005 (GLE69) has been realized.

Production of the cosmogenic isotopes 3H, 7Be, 10Be, and 36Cl in the Earth's atmosphere by solar and galactic cosmic rays

In a follow‐up study to the earlier work of Webber and Higbie (2003) on 10Be production in the Earth's atmosphere by cosmic rays, we have calculated the atmospheric production of the cosmogenic isotopes 3H, 7Be, 10Be, and 36Cl using the FLUKA Monte Carlo code. This new calculation of atmospheric yields of these isotopes is based on 107 vertically incident protons at each of 24 logarithmically spaced energies from 10 MeV to 10 GeV, 102 times the number used in the earlier calculation, along with the latest cross sections. This permits a study of the production due to solar cosmic rays as well as galactic cosmic rays at lower energies where isotope production is a very sensitive function of energy. Solar cosmic ray spectra are reevaluated for all of the major events occurring since 1956. In terms of yearly production of 10Be, only the February 1956 solar event makes a major contribution. For 36Cl these yearly SCR production contributions are 2–5 times larger depending on the solar cosmic ray energy spectra. We have determined the yearly production of 10Be, 36Cl, and other cosmogenic isotopes above 65° geomagnetic latitude for the time period 1940–2006 covering six solar 11‐year (a) cycles. The average peak‐to‐peak 11‐a amplitude of this yearly production is 1.77. The effects of latitudinal mixing alter these direct polar production values considerably, giving an average peak‐to‐peak 11‐a amplitude of 1.48 for the global average production.

Evaluation of the energy spectrum of solar protons according to the balloon measurement data and Monte Carlo simulation

The method for evaluating the energy spectra of solar protons at the boundary of the Earth’s atmosphere according to the data of balloon measurements carried out at the Lebedev Institute of Physics, Russian Academy of Sciences, and the results of Monte Carlo simulation of the processes of proton interaction in the Earth’s atmosphere has been developed. The balloon measurements during solar proton events make it possible to determine the absorption spectra of solar cosmic rays in the atmosphere. Comparison of the experimental data with the results of the simulation of propagation of solar protons (E p = 10 MeV-10 GeV) in the atmosphere, based on GEANT-4, allows determination of the energy spectra of solar protons at the atmospheric boundary. The results of the determination of the energy spectra of solar protons in a number of solar proton events in the current (23th) solar activity cycle are reported.

Derivation of relativistic solar cosmic-ray spectra from the Baksan EAS array data

Fifteen increases in the intensity of solar cosmic rays (SCRs) from 30 investigated ground level enhancement (GLE) events have detected by Baksan EAS arrays in the period from 1981 until now. These data make it possible to refine the high-energy part of the SCR spectra calculated previously according to the data of the world-wide network of neutron monitors. A method for obtaining SCR spectra and calculating the specific yield functions for the Andyrchi, Carpet, and BMD Baksan arrays is briefly described. The SCR spectra for different instants in the GLE event of January 20, 2005 are presented.

Analysis of secondary electron emission spectra of equal-LET protons and α particles for purposes of radiation quality and spaceflight hazard assessment

Amongst the great variety of heavy particles present in the galactic and solar cosmic ray spectra, hydrogen and helium nuclei are significantly more abundant than all other heavier ions and, as such, represent a major radiation hazard to humans in space. Experimental data have suggested that differences in relative biological effectiveness (RBE) exist between the two species at the same value of linear energy transfer (LET). This has consequences for heavily ionising radiation protection procedures, which currently still assume a simple dependence of radiation quality on LET. By analysing the secondary electron (δ-ray) emission spectra of protons and α particles, in terms of the spatial characteristics of energy deposition in cellular targets and the likelihood of complex lesion formation, a numerical quantity representing biological effectiveness is generated. When expressed relative to a reference radiation, this quantity is found to differ for protons and α particles of the same LET, demonstrating not only the ion-specific nature of RBE but also the inadequacy of specifying radiation quality as a function of LET only. Such a method for numerically assessing radiation quality may have implications for procedures for heavy ion protection in space at low doses and for understanding the initial mechanisms of radiation action.