Solar Cosmic Ray Protons Research Articles

Gamma Rays Generated in Nuclear Interactions of Protons Accelerated during Solar Flares

The article considers 30 solar flare events during which the spectra of solar cosmic-ray (SCR) protons with energies above ~80 MeV were recorded in the course of the PAMELA experiment (July 2006–September 2014) and those with energies above ~0.4 GeV recorded during the AMS-02 experiments (June 2011–September 2014). The Konus-Wind data are analyzed for the same time period (2006–2014), during which 176 events with photon energies below 1 MeV and 16 events with energies above 1 MeV were observed. Gamma rays with energies of 1–15 MeV and SCR protons with energies above ~0.1 GeV were simultaneously recorded during only one flare. In the other 15 events, a correlation was noted between the Konus-Wind data and GOES observations of fluxes of SCR protons with energies of ~10–100 MeV. The spectra and angular distributions of solar gamma rays entering into the interplanetary space are calculated with the Monte Carlo method. The ratio of the intensities of gamma-ray 511-keV and 2.223-MeV lines is shown to strongly depend on the profile of the SCR proton spectrum. Observations of the 2.223-MeV line cannot help in the search for solar flares with the generation of solar neutrons and deuterium nuclei.

APPROXIMATION OF THE INTEGRAL ENERGY SPECTRUM OF PROTONS OF SCR IN THE RANGE OF > 1-850 MEV

This work is a continuation of the work (Isaeva E., 2018) in which a new approximation of the in- tegral energy spectrum of solar cosmic ray (SCR) protons was presented in the range > 1-100 MeV. In this work, the comments and wishes of colleagues working in this field were taken into account. First, the comments were taken into account on the form of the functional for approximat- ing the energy spectrum of protons, which must correspond in form to the functionals predicted by particle acceleration theories. Secondly, the previously obtained functional should be checked for high-energy protons with energies >1000 MeV. For the analysis, we used original records of the intensity of the flux of SCR protons according to the data from GOES. The studied sample contains 349 solar proton events (SPE) for the period from 03-02-1986 to 12-02-2018 years, accompanied by protons with energies in the range > 1-850 MeV. Of 349 SPE, 53 were accompanied by high- energy protons with energies > 850 MeV. In this paper, we present the results of approximation of the integral energy spectrum of SCR protons with energies > 1-850 MeV using a functional containing power and ex- ponential functions. A comparative analysis showed that this functional gives a very good approximation for SCR protons with energies in the range > 1-850 MeV.

Calculating the ionization rate induced by GCR and SCR protons in Earth’s atmosphere

This paper explores the applied use of the RUSCOSMICS software package [http://ruscosmics.ru] designed to simulate propagation of primary cosmic ray (CR) particles through Earth’s atmosphere and collect information about characteristics of their secondary component. We report the results obtained for proton fluxes with energy distributions corresponding to the differential spectra of galactic CR (GCR) and solar CR (SCR) during ground level enhancement (GLE) events GLE65 and GLE67. We examine features of the geometry of Earth’s atmosphere, parametrization methods, and describe a primary particle generator. The typical energy spectra of electrons obtained both for GCR and for GLE65 provide information that allows us to quantitatively estimate the SCR contribution to the enhancement of secondary CR fluxes. We also present altitude dependences of ionization rate for GCR and both the GLE events for several geomagnetic cutoff rigidity values. The conclusion summarizes and discusses the prospects for future research.

Individual and grouping track pits etched in the exposed in a free space plastic track detectors

New results concerned to the investigation of depth-dependent the pit-like surface-average and the grouping track-density distributions in the cosmic ray exposed column of CN-85 and CR-39 plastic solid state nuclear track detectors (SSNTD) are presented. Two main sources: solar cosmic ray protons and recoil nuclei for very short (length <3 μm) track-pit formation are considered. Theoretical estimation of the total, uniform track-pit density indicates on failure of evidence of some additional radiation effects, partially, hypothetically conditioned with the Erzion theory. Some quantitative proofs of this hypothesis have been obtained in the measurements of the pit-groups. Totally, up to this time it was registered near of 30 pit groups with the surface pit-density in the interval of (1-15) × 106 cm2, that is two-three orders of magnitude higher than uniformly distributed track-pits on the same CR-39 plate surface. As a result of layer-by-layer investigation of the exposed CN-85 stock arrangement three pit swarms exactly correlated with the end point of high ionizing primary charge particle tracks were observed. Obtained data are considered in according to submission based on the probability of detection for the negative charged cosmic ray Erzion particles stopping events.

Verification of magnetic field models based on measurements of solar cosmic ray protons in the magnetosphere

Measurements of solar cosmic ray (SCR) protons in the magnetosphere can be used to verify models of the Earth’s magnetic field. The latitudinal profiles of precipitating SCRs with energies of 1–90 MeV were measured on the CORONAS-F low-orbiting satellite during a strong magnetic storm on October 29–30, 2003. A flux of precipitating protons can remain equal to the interplanetary flux only due to a strong pitch angle diffusion that originates when the radius of the field line curvature is close to that of the particle rotation Larmor radius. The observed boundaries of the strong diffusion region can be compared with the boundaries anticipated according to the models of the magnetic field of the Earth’s magnetosphere. The adiabaticity parameter values, calculated for several instants of the CORONAS-F satellite pass based on the TS05 and parabolic models, do not always correspond to measurements. How possible changes in the model configurations of the magnetic field can allow us to eliminate discrepancies with the experiment and to explain why solar protons with energies of several megaelectronvolts penetrate deep in the Earth’s inner magnetosphere is considered here.

Optimum conditions of observation of tubular-loop structures of the interplanetary magnetic field and estimation of their lifetime

Basic conditions of observation of IMF tubular-loop structures are considered on the basis of experimental data of studying the fluxes of solar cosmic ray protons in the interplanetary medium. Lifetime of these structures, when their sources disappear on the Sun, is estimated.

Model of the solar cosmic ray burst on March 19, 1990

The causes of oscillation of the solar cosmic ray flux and alternating-sign anisotropy with a period of three hours to two minutes in March 1990 measured on the Granat satellite are analyzed in this paper. It is shown that they are caused by the motion of solar cosmic ray protons with the energy 1–100 MeV in loop structures of solar magnetic fields of the chromosphere and the corona transferred into the interplanetary medium by plasma of the solar wind. A model description of the observation data is presented.

On the mean free path of solar cosmic rays – I. Protons

The spatial transport of charged particles in the presence of pure slab Alfven waves, pure isotropic magnetosonic waves and their mixture is considered using Monte Carlo particle simulations. We show that the mean free path of solar cosmic ray protons strongly depends on the assumed spectrum and amplitude of MHD turbulence but much less on the type of the considered waves. It is demonstrated that, for realistic solar wind parameters, the presented wide range wave spectrum models can reproduce the observed mean free path in a particular SEP event but not in a wide range of rigidity characterized by the Palmer's `consensus'.

Energetic proton irradiation history of the howardite parent body regolith and implications for ancient solar activity

Abstract— Previous studies have shown that the Kapoeta howardite, as well as several other meteorites, contains excess concentrations of cosmogenic Ne in the darkened, solar‐irradiated phase compared to the light, non‐irradiated phase. The two explanations offered for the nuclear production of these Ne excesses in the parent body regolith are either from galactic cosmic‐ray proton (GCR) irradiation or from a greatly enhanced flux of energetic solar “cosmic‐ray” protons (SCR), as compared to the recent solar flux. Combining new isotopic data we obtained on acid‐etched, separated feldspar from Kapoeta light and dark phases with literature data, we show that the cosmogenic 21Ne/22Ne ratio of light phase feldspar (0.80) is consistent with only GCR irradiation in space for ∼3 Ma. However, the 21Ne/22Ne ratio (0.68) derived for irradiation of dark phase feldspar in the Kapoeta regolith indicates that cosmogenic Ne was produced in roughly equal proportions from galactic and solar protons. Considering a simple model of an immature Kapoeta parent body regolith, the duration of this early galactic exposure was only ∼3–6 Ma, which would be an upper limit to the solar exposure time of individual grains. Concentrations of cosmogenic 21Ne in pyroxene separates and of cosmogenic 126Xe in both feldspar and pyroxene are consistent with this interpretation. The near‐surface irradiation time of individual grains in the Kapoeta regolith probably varied considerably due to regolith mixing to an average GCR irradiation depth of ∼10 cm. Because of the very different depth scales for production of solar ∼Fe tracks, SCR Ne, and GCR Ne, the actual regolith exposure times for average grains probably differed correspondingly. However, both the SCR 21Ne and solar track ages appear to be longer because of enhanced production by early solar activity. The SCR/GCR production ratio of 21Ne inferred from the Kapoeta data is larger by a at least a factor of 10 and possibly as much as a factor of ∼50 compared to recent solar particle fluxes. Thus, this study indicates that our early Sun was much more active and emitted a substantially higher flux of energetic (&gt;10 MeV/nucleon) protons.

Thin-target cross sections of proton-induced reactions on barium and solar cosmic ray production rates of xenon-isotopes in lunar surface materials

Thin-target excitation functions for the proton-induced production of radionuclides and stable Xe-isotopes from barium were measured at the JULIC isochronous cyclotron of the IKP/KFA Jülich up to E p=45MeV using the stacked-foil technique. Additionally, thin-target cross sections for the production of radionuclides from Ba were determined at 147.5 MeV using the synchrocyclotron of the IPN Orsay. For stable Xe-isotopes the thin-target data are in severe disagreement with earlier measurements. The reasons for these discrepancies are discussed. For the experimental excitation functions a detailed hybrid model analysis was performed using the code ALICE LIVERMORE 87, which in contrast to earlier formulations of the model takes into account experimental mass data, multiple preequilibrium nucleon emission and non-integer initial exciton numbers. In general, the a priori calculations satisfactorily reproduce the experimental excitation functions. Some discrepancies have to be attributed to the neglect of preequilibrium emission of alpha-particles and to the use of average nuclear parameters in the calculations for 138Ba, which has a magic neutron configuration. Using the new experimental excitation functions up to 45 MeV and calculated ones between 45 to 200 MeV, depth-dependent production rates for the production of stable Xe isotopes from Ba by solar cosmic ray protons in the lunar surface are calculated and compared with the results of earlier investigations. The improvements still necessary to come to a complete and adequate description of cosmogenic Xe isotopes in extraterrestrial matter are outlined.

Neon isotope studies of Fayetteville and Kapoeta meteorites and clues to ancient solar activity

Pyroxene grain-size separates, from both dark (D) and light (L) portions of two gas-rich meteorites, Fayetteville and Kapoeta, were chemically etched to remove the surficial solar wind (SW). These samples were studied mass spectrometrically for neon to decipher the long-term average solar flare (SF) neon composition and fluxes as well as the solar cosmic ray (SCR) proton fluxes from the ancient Sun during the solar system formation. Based on the results from Fayetteville and Kapoeta, we deduce that the SF-Ne composition from the ancient Sun is 20 22 = 11.6 ± 0.2 and 21 22 = 0.030 , which is similar to that deduced from our lunar sample studies (Nautiyal et al., 1981, 1986). The SF, SCR and galactic cosmic ray (GCR) produced neon isotopes are resolved into their individual components in the neon mixtures of these etched pyroxenes under the assumption that GCR-produced neon in pyroxenes from the dark and light phases of Fayetteville and Kapoeta are similar. We find significant excess of 21Ne produced by SCR protons ( p) in these etched pyroxenes. This observed excess 21Ne can be explained if the SCR proton fluxes from the ancient Sun are considered to be about three orders of magnitude higher than those from the contemporary Sun. This inference is supported by the significant excess of implanted SF- 20Ne ( E > 1 MeV/amu) observed here in the irradiated pyroxenes of Fayetteville and Kapoeta. The agreement of p ( E > 10 MeV/amu)/ Ne ( E > 1 MeV/amu) ratio for the ancient solar flares deduced in this study with the same ratio for the contemporary solar flares deduced from lunar sample studies suggests that these observed neon excesses were most probably produced by the solar flare irradiation of these grains during surface irradiation on the regolith of the meteorite parent bodies during the early solar system.

Relationship between long‐term phase advances in high‐latitude VLF wave propagation and solar energetic particle fluxes

Anomalous advances of OMEGA VLF navigation system (10.2‐kHz) signals during three extended periods (totaling 60 days) of solar cosmic ray event activity during 1982 are examined and compared with energetic proton, alpha particle, and electron precipitation into the polar cap ionosphere. Time profiles of the OMEGA 10.2‐kHz Hawaii‐to‐Norway path phase advance are found to be almost congruent with the time profiles of the logarithms of the energetic proton fluxes precipitating into the polar cap as determined from instruments aboard the polar orbiting NOAA‐6 satellite and the GOES‐2 geostationary satellite. Although both energetic alpha particles and electrons contribute to the anomalous phase advance experienced by the 10.2‐kHz Hawaii‐to‐Norway OMEGA signal, a simple, empirical algorithm reasonably relates the observed phase advance to the observed differential fluxes of 6‐MeV solar cosmic ray protons.

Production of He, Ne, and Ar isotopes and U236in lunar materials by solar cosmic ray protons-production rate calculations

A computer program has been written for calculating rates of formation of solar cosmic ray (SCR) proton-produced nuclides at 50 depths ranging from 0 to 25 g/cm2 in materials with the average atomic number Ž = 13. Production rates are presented for 2π isotropic irradiation of a semi-infinite plane surface for two incident SCR spectra of different spectral shapes: spectrum A, derived from data for the years 1959 and 1960, and spectrum B, derived from data for the years 1956, 1959, and 1960. For each spectrum, two cases are considered: (1 ) integration of the production equation from threshold energy to 45 MeV and (2) integration from threshold to 200 MeV. Data are presented which permit the calculation of the following production rates: (1) 3H, 3He, 3HeT (≡ 3H + 3He), and 4He in bulk lunar samples, (2) 20Ne, 21Ne, 22Ne, 22Na, and 22NeT (≡ 22Ne + 22Na) in lunar samples containing variable amounts of Mg, Al, Si, and Na, and (3) 36Ar, 37Ar, 38Ar, and 39Ar in lunar samples containing variable contents of Ca and, for 39Ar, also variable contents of Ti. In addition, 236U/238U saturation ratios in natural U are presented as a function of depth. Comparison of SCR production rates with production rates by galactic cosmic ray (GCR) protons for 3HeT, 21Ne, and 38Ar shows that SCR production dominates overwhelmingly at 0.0 g/cm2 and remains at least comparable to depths of about 5–10 g/cm2 for spectrum B. Isotopic ratios of He and Ne produced by SCR protons are distinctly different from those produced by GCR protons at all depths; the GCR value of 36Ar/38Ar, however, falls within the range of SCR-produced values.

Abundances of Solar Cosmic Ray Protons and Alpha Particles for 1969-1972

Hsieh and Simpson have given the abundance ratio of alpha particles and protons for seven solar proton events in 1967. In addition, Lanzerotti and Maclennan have analyzed seven events that occurred during the December 1967 to November 1969 period, which includes the maximum of solar cycle 20. Herein a similar analysis is reported based on OV5-6 satellite data for eight events during the November 1969 to November 1972 period after the cycle maximum. The flare-averaged alpha particle to proton ratio reported here varies as 0.032E$sup - 0$.$sup 3$ in the particle energy range from 2.7 to 8.0 MeV/nucleon. Following the precedent of Lanzerotti and Robbins the alpha particle to proton ratios are determined for equal energy/nucleon, equal rigidity, and equal energy/charge. Finally, a comparison of the yearly average of the total integrated proton and alpha particle fluxes is made for the maximum and descending periods of solar cycle 20. (AIP)

On the generation of high-energy particles in solar flares

This paper discusses the relationship between some characteristics of microwave type IV radio bursts and solar cosmic ray protons of MeV energy. It is shown that the peak flux intensity of those bursts is almost linearly correlated with the MeV proton peak flux observed by satellites near the Earth and that protons and electrons would be accelerated simultaneously by a similar mechanism during the explosive phase of solar flares. Brief discussion is given on the propagation of solar cosmic rays in the solar envelope after ejection from the flare regions.

SOME CHARACTERISTICS OF MICROWAVE TYPE IV RADIO BURSTS AND THE ACCELERATION OF SOLAR COSMIC RAYS

ABSTRACT This paper discusses the relationships between some characteristics of microwave type IV radio bursts and solar cosmic ray protons of MeV energy. It is shown that the peak flux intensity of those bursts is almost linearly correlated with the MeV proton peak flux observed by satellites near the earth. The rise times of type IV microwave emissions are, however, independent of the proton peak fluxes. Using these results, discussion is given on the acceleration process and duration for both protons and electrons. Key words: solar radio activity - solar cosmic rays

Cosmic-ray produced 59Ni and its astrophysical and geophysical implications

The processes for the production of 59Ni in meteorites and in micrometeorites have been studied. For large bodies, 59Ni nuclei are produced by galactic cosmic rays through (i) the spallation reaction of 60Ni, 63Cu, etc., and (ii) radiative capture of secondary neutrons slowed down in meteorites: 58Ni(n, γ) 59Ni. For small bodies, the contribution of solar cosmic rays is important. The main contribution comes from the (α, n) reaction, induced by solar cosmic-ray α particles: 59Fe(α, n)59Ni, and the secondary contribution is due to solar cosmic-ray protons: 60Ni(p, pn)59Ni and 59Co(p, n)59Ni. From the use of solar cosmic-ray data, the 59Ni activity in micrometeorites has been calculated. Under conditions of radioactive equilibrium, the 59Ni activity is 220 d.p.m./g Ni, if 93% of the micrometeorites are composed of stone and 7% of iron. The contribution of solar cosmic-ray protons is 15 d.p.m./g Ni, giving a total of 235 d.p.m./g Ni. Experimental information in the 59Ni sedimentation rate will determine the fallout rate of extraterrestrial nickel–iron. Measurement of the 59Ni activity in pelagic clay, dated by the Th–Io method will provide information concerning the variation of solar activity, as represented by the solar cosmic-ray intensity, over the last few hundred thousand years.

On the influence of composition and spectra of solar cosmic rays on the intensity ratio [formula omitted] in polar-glow aurora

Using exponential rigidity spectra for solar cosmic ray protons and alpha particles, it is shown that the presence of alpha particles increases the intensity ratio I(λ5577) I(λ3914) in polar-glow aurora and, for a constant composition, steepening of rigidity spectra has the same effect. Representative values for I(λ5577) I(λ3914) show that variations in composition and spectral shape in the course of solar cosmic ray events, individually, produce changes of comparable magnitude in the intensity ratio.

Low-energy solar cosmic rays and the geomagnetic storm of May 12, 1959

During a strong geomagnetic storm on May 11- 12, 1959, and following a class 3+ chromospheric solar flare on May 10, a large intensity of low-energy solar cosmic-ray protons was observed in a balloon flight at 30-km altitude at Minneapolis, Minn. The results obtained with an ion chamber, a Geiger counter, and a scintillation counter are reported. The proton flux of energy above 100 Mev varied from 52 to 1.7/cm/sup 2/ -sec- steradian during the time 0400 to 1800 UT on May 12. The spectrum obtained with the counting instruments is consistent with detailed emulsion studies and has the form N(> E)= CE/sup - s. With E in Mev, gamma varied from 5 to 2 during the time period. The scintillation counter showed excess gamma radiation from the nuclear effects of the cosmic-ray protons and intense bursts of auroral x rays, particularly at 0835 UT on May 12. The solar optical and radio features of the flare are discussed, and the relationship of the polar-cap ionospheric blackout tc the Minneapolis measurements is considered. The cosmic-ray protons at Minneapolis are measured at energies well below the normal Stormer cutoff for that latitude. Several theories on this subject are presented. (auth)