Abstract
Energetic solar flare particles contain rich information concerning mechanisms of particle acceleration on the Sun and subsequent transport through turbulent interplanetary space. Even the most energetic particles, in particular protons with kinetic energy above ∼500 MeV, may undergo coronal and interplanetary propagation effects, disturbing their accelerated injection spectrum after release from the solar flare. Relativistic solar proton events are recorded by neutron monitors at ground level. A detailed knowledge of the response of these ground-based detectors to the impact by a beam of protons on the top of the atmosphere is required to analyze these observations. The spectral index of arriving protons can be obtained from the response of the world-wide network of neutron monitors provided their directional anisotropy is known. The spectral index may also by determined from the relative enhancements in count rates of two similar detectors at different altitudes but similar asymptotic cones of acceptances, or from the relative enhancements of two detectors with different spectral sensitivities but at the same location of high latitude. Ground level enhancements from solar flare protons have been recorded at Sanae, Antarctica, since 1971 by two neutron monitors with different sensitivities to primary protons in the rigidity range from ≲1 GV to ∼5 GV. Spectral indexes of about 20 of these more energetic solar flare proton events have been determined from the two detector enhancements recorded at Sanae. These indexes do not show any increase (softening of the relativistic proton spectra) with increasing heliolongitude away from the preferred IMF connection region as was obtained for 20–80 MeV protons. Furthermore, most of the enhanced count rates show fluctuations larger than statistical, indicative of propagation in a mostly turbulent interplanetary magnetic field.
Similar content being viewed by others
References
Agnew, H. M., Bright, W. C., and Froman, D.: 1947, ‘Distribution of Neutrons in the Atmosphere,Phys. Rev. 72, 203–206.
Akimov, V. V., Belov, A. V., Chertok, I. M., Kurt, V. G., Leikov, N. G., Magun, A., and Melnikov, V. F.: 1993, ‘High Energy Gamma-Rays at the Late Stage of the Large Solar Flare of June 15, 1991 and Accompanying Phenomena’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 111–114.
Alvarez, M., Dorman, L. I., Gallegos, A., Libin, I. Ya., Ishkov, V., Miroshnichenko, L. I., and Perez-Peraza, J. 1990, ‘Fluctuations of Galactic Cosmic Rays in Periods of Solar Flares’,Proc. 21st Int. Cosmic Ray Conf., Adelaide 6, 400–403.
Bazilevskaya, G. A., Makhmutov, V. S., Grigoryan, M. S., and Charakhchyan, T. N.: 1983a, ‘Energy Spectra of Solar Cosmic Rays According to Balloon and Neutron Monitor Data’,Proc. 18th Int. Cosmic Ray Conf., Bangalore 4, 194–197.
Bazilevskaya, G. A., Stozhkov, Yu. I., Makhmutov, V. S., Charakhchyan, T. N., Borovkov, L. P., Vashenyuk, E. V., Lazutin, L. L., and Bimenov, D. Yu.: 1983b, ‘The Results of Stratospheric Measurements of Solar Cosmic Rays with Energy >100 MeV in October 1981,Proc. 18th Int. Cosmic Ray Conf., Bangalore 4, 198–201.
Beeck, J. and Wibberenz, G.: 1986, ‘Pitch Angle Distributions of Solar Energetic Particles and the Local Scattering Properties of the Interplanetary Medium’,Astrophys. J. 311, 437–450.
Bieber, J. W. and Burger, R. A.: 1990, ‘Cosmic Ray Streaming in the Born Approximation’,Astrophys. J. 348, 597–607.
Bieber, J. W., Evenson, P. A., and Pomerantz, M. A.: 1986, ‘Focusing Anisotropy of Solar Cosmic Rays’,J. Geophys. Res. 91, 8713–8724.
Bieber, J. W., Evenson, P. A., and Matthaeus, W. H.: 1987a, ‘Magnetic Helicity of the Parker Field’,Astrophys. J. 315, 700–705.
Bieber, J. W., Evenson, P., and Matthaeus, W. H.: 1987b, ‘Magnetic Helicity of the IMF and the Solar Modulation of Cosmic Rays’,Geophys. Res. Letters 14, 864–867.
Bieber, J. W., Matthaeus, W. H., Smith, C. W., Wanner, W., Kallenrode, M.-B., and Wibberenz, G.: 1994, ‘Proton and Electron Mean Free Paths: The Palmer Consensus Revisited’,Astrophs. J. 420, 294–306.
Borovkov, L. P., Lazutin, L. L., Shumilov, O. I., and Vashenyuk, E. V.: 1987, ‘Injection Characteristics of Energetic Particles on the Sun During GLE’,Proc. 20th Int. Cosmic Ray Conf., Moscow 3, 124–127.
Cane, H. V., McGuire, R. E., and von Rosenvinge, T. T.: 1986, ‘Two Classes of Solar Energetic Particle Events Associated with Impulsive and Long Duration Soft X-ray Flares’,Astrophys. J. 301, 448.
Carmichael, H.: 1962, ‘High Energy Solar Particle Events,Space Sci. Rev. 1, 28–61.
Carmichael, H.: 1968, ‘Cosmic Rays (Instruments)’, in C. M. Minnis (ed.),Ann. IQSY 1, 178–197, M.I.T. Press.
Chen, J. and Bieber, J. W.: 1993, ‘Cosmic Ray Anisotropies and Gradients in Three Dimensions’,Astrophys. J. 405, 375–389.
Cliver, E. W., Kahler, S. W., Shea, M. A., and Smart, D. F.: 1982, ‘Injection Onsets of ∼2 GeV Protons, ∼1 MeV Electrons, and ∼100 keV Electrons in Solar Cosmic Ray Flares’,Astrophys. J. 260, 362–370.
Cramp, J. L., Duldig, M. L., and Humble, J. E.: 1993, ‘The GLE of 22 October 1989’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 51–54.
Datlowe, D.: 1972, ‘Association Between Interplanetary Shock Waves and Delayed Solar Particle Events’,J. Geophys. Res. 77, 5374–5384.
Debrunner, H. and Lockwood, J. A.: 1980, ‘The Spatial Anisotropy, Rigidity Spectrum, and Propagation Characteristics of the Relativistic Solar Particles During the Event on May 7, 1978’,J. Geophys. Res. 85, 6853–6860.
Debrunner, H. Lockwood, J. A., and Flückiger, E. O.: 1982, Preprint, ‘8th Europe Cosmic Ray Symp.’, Rome.
Debrunner, H., Flückiger, E. O., Lockwood, J. A., and McGuire, R. E.: 1984, ‘Comparison of the Solar Cosmic Ray Events on May 7, 1978, and November 22, 1977’,J. Geophys. Res. 89, 769–774.
Debrunner, H., Flückiger, E., Grädel, H., Lockwood, J. A., and McGuire, R. E.: 1988, ‘Observations Related to the Acceleration, Injection and Interplanetary Propagation of Energetic Protons During the Solar Cosmic Ray Event on February 16, 1984’,J. Geophys. Res. 93, 7206–7216.
Debrunner, H., Lockwood, J. A., and Ryan, J. M.: 1992, ‘The Solar Flare Event on 1990 May 24: Evidence for Two Separate Particle Accelerations’,Astrophys. J. 387, L51-L54.
Debrunner, H., Lockwood, J. A., Ryan, J. M., McConnell, M., Schönfelder, V., Aarts, H., Bennett, K., and Winkler, C.: 1993, ‘Neutrons from the 15 June 1991 Solar Flare’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 115–118.
Dorman, L. I. and Pakhomov, N. I.: 1979, ‘The Dependence of the Integral Generation Multiplicity of Neutron Component at Various Depths in the Atmosphere on Zenith Angle of Primary Particle Incidence’,Proc. 16th Int. Cosmic Ray Conf., Kyoto 4, 416–420.
Dorman, L. I. and Venkatesan, D.: 1993, ‘Solar Cosmic Rays’,Space Sci. Rev. 183, 64–362.
Dröge, W.: 1993, D. A. Leahyet al. (eds.), ‘Heliospheric Propagation of Cosmic Rays’, Rapporteur paper inProc. 23rd Int. Cosmic Ray Conf., Calgary, World Scientific, Singapore, pp.4185–212.
Dubinsky, J. Ilencik, J. and Kudela, K.: 1979, ‘Solar Proton Event from November 22, 1977’,Proc. 16th Int. Cosmic Ray Conf., Kyoto 12, 297–300.
Duggal, S. P.: 1979, ‘Relativistic Solar Cosmic Rays’,Rev. Geophys. Space Phys. 17, 1021–1058.
Duggal, S. P. and Pomerantz, M. A.: 1973, ‘Anisotropies in Relativistic Cosmic Rays from the Invisible Disk of the Sun’,J. Geophys. Res. 78, 7205–7220.
Earl, J. A.: 1974, ‘The Diffusive Idealization of Charged Particle Transport in Random Magnetic Fields’,Astrophys. J. 193, 231–242.
Earl, J. A.: 1981, ‘Analytical Description of Charged Particle Transport Along Arbitrary Guiding Field Configurations’,Astrophys. J. 251, 739–755.
Elliot, H.: 1952, in J. G. Wilson (ed.), ‘Time Variations of Cosmic Ray Intensity’,Prog. in Cosmic Ray Phys. 1, Amsterdam, p. 455–511.
Filippov, A. T., Krivoshapkin, P. A., Transky, I. A., Kuzmin, A. I., Krymsky, G. F., Niskovskikh, A. S., and Berezhko, E. G.: 1991, ‘Solar Cosmic Flare on September 29, 1989 by data of the Yakutsk Array Complex’,Proc. 22nd Int. Cosmic Ray Conf., Dublin 3, 113–116.
Gentile, L. C.: 1993, ‘Ground Level Enhancement Database for Solar Cycle 22: an Update’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 63–66.
Goldstone, H. L. and Matthaeus, W. H.: 1981, ‘The Role of Helicity in Cosmic Ray Transport Theory’,Proc. 17th Int. Cosmic Ray Conf., Paris 3, 294–297.
Hatton, C. J.: in J. G. Wilson and S. A. Woudhuysen (eds.), 1971, ‘The Neutron Monitor’,Progress Elementary Part. Cosmic Ray Phys., North-Holland, Amsterdam.
Heristchi, D. J., Trottet, G. and Perez-Peraza, J.: 1976, ‘Upper Cutoff of High Energy Solar Protons’,Solar Phys. 49, 151–157.
Hess, W. N., Patterson, H. W., and Wallace, R.: 1959, ‘Cosmic Ray Neutron Energy Spectrum’,Phys. Rev. 116, 445–457.
Hughes, E. B. and Marsden, P. L.: 1966, ‘Response of a Standard IGY Neutron Monitor’,J. Geophys. Res. 71, 1435–1444.
Humble, J. E., Duldig, M. L., Smart, D. F., and Shea, M. A.: 1991, ‘Detection of 0.5–15 GeV Solar Protons on 29 September 1989 at Australian Stations’,Geophys. Res. Letters 18, 737–740.
Inoue, I., Wada, M., and Kondo, I.: 1983,Cosmic Ray Tables No. 1, World Data Center C2 for Cosmic Rays, Itabashi, Tokyo.
Jokipii, J. R.: 1966, ‘Cosmic Ray Propagation. I. Charged Particles in a Random Magnetic Field’,Astrophys. J. 146, 480–487.
Kahler, S. W., Shea, M. A., Smart, D. F., and Cliver, E. W.: 1991, ‘Ground Level Events from Impulsive Flares’,Proc. 22nd Int. Cosmic Ray Conf., Dublin 3, 21–24.
Kananen, H., Tanskanen, P. J., Gentile, L. C., Shea, M. A., and Smart, D. F.: 1991, ‘A Quarter of a Century of Relativistic Solar Cosmic Ray Events Recorded by the Oulu Neutron Monitor’,Proc. 22nd Int. Cosmic Ray Conf., Dublin 3, 145–148.
King: 1993, OMNItape SM-41E, World Data Center A, Rockets and Satellites, Goddard Space Flight Center.
Kocharov, G. E., Chuikin, E. I., Kocharov, L. G., Kovaltsov, G. A., Melnikov, V. F., Podstrigach, T. S., and Usoskin, I. G.: 1993a, ‘High Energy Gamma Rays from 1991 June 15 Solar Flare as Evidence of Proton Acceleration up to 10 GV’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 123–126.
Kocharov, G. E., Kocharov, L. G., Kovaltsov, G. A., Shea, M. A., Smart, D. F., Armstrong, T. P., Pyle, K. R., and Chuikin, E. I.: 1993b, ‘Evidence for Extended Neutron and Gamma-Ray Generation During Two Solar Flares’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 107–110.
Kondo, T. and Struminsky, A.: 1993, ‘Peculiarities of Solar Proton Spectrum in Stratosphere and Geostationary Orbit on 2–3 November 1992’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 5–8.
Kovaltsov, G. A., Efimov, Yu. E., and Kocharov, L. G.: 1993, ‘Ground Level Energetic Solar Particle Event on 24 May 1990: Possibility of Direct Solar Neutron Detection’,Solar Phys. 144, 195–198.
Lockwood, J. A.: 1968, ‘Cosmic Ray Flare Effect of January 28, 1967, as Recorded by Neutron Monitors’,J. Geophys. Res. 73, 4247–4260.
Lockwood, J. A. and Webber, W. R.: 1967, ‘Differential Response and Specific Yield Functions of Cosmic Ray Neutron Monitors’,J. Geophys. Res. 72, 3395–3402.
Lockwood, J. A., Webber, W. R., and Hsieh, L.: 1974, ‘Solar Flare Proton Rigidity Spectra Deduced from Cosmic Ray Neutron Minitor Observations’,J. Geophys. Res. 79, 4149–4155.
Lockwood, J. A., Debrunner, H., Flückiger, E. O., Neuenschwander, H., and Schubnell, M.: 1982, ‘A Model of Propagation of Solar Flare Particles and Its Application to Cosmic Ray Ground Level Events’,J. Geophys. Res. 87, 4338–4344.
Lockwood, J. A., Debrunner, H., and Flückiger, E. O.: 1990a, ‘Indications of Diffusive Coronal Shock Acceleration of Protons in Selected Solar Cosmic Ray Events’,J. Geophys. Res. 95, 4187–4201.
Lockwood, J. A., Debrunner, H., Flückiger, E. O., and Grädel, H.: 1990b, ‘Proton Energy Spectra at the Sun in the Solar Cosmic Ray Events on 1978 May 7 and 1984 February 16’,Astrophys. J. 355, 287–294.
Lumme, M., Nieminen, M., Peltonen, J., Torsti, J. J., Vainikka, E., and Valtonen, E.: 1983, ‘Time-Dependent Rigidity Spectrum and Spatial Anisotropy of the Ground Level Event on May 7, 1978’,Proc. 18th Int. Cosmic Ray Conf., Bangalore 4, 157–160.
Lumme, M., Torsti, J. J., Vainikka, E., Peltonen, J., Nieminen, M., Valtonen, E., and Arvela, H.: 1985, ‘Monte Carlo Calculations of Relativistic Solar Proton Propagation in Interplanetary Space’,Proc. 19th Int. Cosmic Ray Conf., La Jolla 4, 364–367.
Makgamathe, S. and Stoker, P. H.: 1990, ‘Relativistic Solar Proton Spectra Recorded at Sanae, Antarctica. 1. Experimental Evidence’,Proc. 21st Int. Cosmic Ray Conf., Adelaide 5, 13–16.
Matthaeus, W. H. and Goldstein, M. L.: 1982, ‘Measurement of the Rugged Invariants of Magneto Hydrodynamic Turbulence in the Solar Wind’,J. Geophys. Res. 87, 6011–6028.
Mischke, C. F. W., Stoker, P. H., and Duvenage, J.: 1973, ‘The Neutron Moderated Detector and the Determination of Rigidity Dependence of Protons from the 1/2 September 1971 Solar Flare’,Proc. 13th Int. Cosmic Ray Conf., Denver 2, 1570–1575.
Moraal, H., Potgieter, M. S., Stoker, P. H., and van der Walt, A. J.: 1989, ‘Neutron Monitor Latitude Survey on Cosmic Ray Intensity During the 1986/1987 Solar Minimum’,J. Geophys. Res. 94, 1459–1464.
NOAA: 1981, National Oceanic and Atmospheric Administration,Solar Geophysical Data, Natl. Geophys. Data Center, Boulder, Colo.,447(1).
NOAA: 1990,Solar Geophysical Data, Natl. Geophys. Data Center, Boulder, Colo.,555(2).
NOAA: 1992,Solar Geophysical Data, Natl. Geophys. Data Center, Boulder, Colo.,580(2).
NOAA: 1993,Solar Geophysical Data, Natl. Geophys. Data Cent, Boulder, Colo.,585(2).
Otaola, J. A. and Valdes-Galicia, J. F.: 1993, ‘Magnetic Helicity Influence on Solar Particle Propagation: Study of 8 Solar Proton Helios Events’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 207–210.
Palmer, I. D.: 1982, ‘Transport Coefficients of Low-Energy Cosmic Rays in Interplanetary Space’,Rev. Geophys. Space Phys. 20, 335–351.
Potgieter, M. S., Raubenheimer, B. C., Stoker, P. H., and van der Walt, A. J.: 1980, ‘Modulation of Cosmic Rays During Solar Minimum. 2. Cosmic Ray Latitude Distribution at Sea Level During 1976’,S. Africa J. Phys. 3, 77–89.
Pyle, K. R. and Simpson, J. A.: 1991, ‘Observation of a Direct Solar Neutron Event on 22 March 1991 with the Haleakala, Hawaii, Neutron Monitor’,Proc. 22nd Int. Cosmic Ray Conf., Dublin 3, 53–56.
Raubenheimer, B. C.: 1972, ‘Various Aspects of the Attenuation Coefficient of a Neutron Monitor’, Ph.D. Thesis, Potchefstroom University for C.H.E.
Raubenheimer, B. C. and Stoker, P. H.: 1974, ‘Various Aspects of the Attenuation Coefficient of a Neutron Monitor’,J. Geophys. Res. 79, 5069–5076.
Raubenheimer, B. C. and Van Niekerk, F.: 1981, ‘The Calculation of Differential Response Functions from Latitude Surveys. II. Results and Discussion’,Proc. 17th Int. Cosmic Ray Conf., Paris 10, 297–300.
Raubenheimer, B. C., Flückiger, E. O., Mischke, C. F. W., and Potgieter, M. S.: 1980, ‘Comparison Bbetween the Experimental and Theoretical Responses of Neutron Monitors’,S. Africa J. Phys. 3, 29–35.
Raubenheimer, B. C., Van Niekerk, F., and Potgieter, M. S.: 1981, ‘The Calculation of Differential Response Functions from Latitude Surveys. I. Theory’,Proc. 17th Int. Cosmic Ray Conf., Paris 4, 321–324.
Roelof, E. C.: 1969, in H. Ogelman and J. R. Wayland (eds.),Lectures in High Energy Astrophysics, Washington, NASA SP-199.
Shea, M. A.: 1990, ‘Solar Cosmic Rays, 1960–1989’,Proc. 21st Int. Cosmic Ray Conf., Adelaide 12, 196–204.
Shea, M. A. and Smart, D. F.: 1990, ‘A Summary of Major Solar Proton Events’,Solar Phys. 127, 297–320.
Shea, M. A., Smart, D. F., Wilson, M. A., and Flückiger, E. O.: 1991a, ‘Possible Ground Level Measurements of Solar Protons During the 19 October 1989 Solar Cosmic Ray Event’,Geophys. Res. Letters 18, 829–832.
Shea, M. A., Smart, D. F., and Pyle, K. R.: 1991b, ‘Direct Solar Neutrons Detected by Neutron Monitors on May 1990’,Geophys. Res. Letters 18, 1655–1658
Shea, M. A., Smart, D. F., Swinson, D. B., and Wilson, M. D.: 1993, ‘High Energy Cosmic Ray Modulation in March–June 1991’,Proc. 23rd Int. Cosmic Ray Conf., Calgary,3, 735–738.
Simnett, G. M.: 1991, ‘Energetic Particle Production in Flares’,Phil. Trans. Roy. Soc. London A336, 439–450.
Simpson, J. A.: 1951, ‘Neutrons Produced in the Atmosphere by the Cosmic Radiation’,Phys. Rev. 83, 1175–1188.
Simpson, J. A.: 1958, ‘Solar Flare Cosmic Rays and Their Propagation’,Nuovo Cimento Suppl. 8(II), 133–160.
Simpson, J. A. and Uretz, R. B.: 1949, ‘On the Latitude Dependence of Nuclear Integrations and Neutrons at 30,000 Feet’,Phys. Rev. 76, 569–570.
Simpson, J. A. and Uretz, R. B.: 1953, ‘Cosmic Ray Neutron Production in Elements as a Function of Latitude and Altitude’,Phys. Rev. 90, 44–50.
Simpson, J. A., Fonger, W., and Treiman, S. B.: 1953, ‘Cosmic Radiation Intensity-Time Variation and Their Origin. I. Neutron Intensity Variation Method and Meteorological Factors’,Phys. Rev. 90, 934–950.
Smart, D. F. and Shea, M. A.: 1989, ‘Solar Proton Events During the Past Three Solar Cycles’,J. Spacecraft and Rockets 26, 403–415.
Smart, D. F., Shea, M. A., and Tanskanen, P. J.: 1971, ‘A Determination of the Spectra, Spatial Anisotropy, and Propagation Characteristics of the Relativistic Solar Cosmic Ray Flux on November 18, 1968’,Proc. 12th Int. Cosmic Ray Conf., Hobart 2, 483–488.
Smart, D. F., Shea, M. A., Humble, J. E., and Tanskanen, P. J.: 1979, ‘A Model of the 7 May 1978 Solar Cosmic Ray Event’,Proc. 16th Int. Cosmic Ray Conf., Kyoto 5, 238–243.
Smart, D. F., Shea, M. A., and Flückiger, E. O.: 1987, ‘Unusual Aspects of the Ground Level Cosmic Ray Event of 7/8 December 1982’,Proc. 20th Int. Cosmic Ray Conf., Moscow 3, 135–138.
Smart, D. F., Shea, M. A., and Gentile, L. C.: 1993a, ‘The Relativistic Solar Proton Event of 11 June 1991’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 55–58.
Smart, D. F., Shea, M. A., and Gentile, L. C.: 1993b, ‘The Relativistic Solar Proton Event of 15 June 1991’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 59–62.
Smith, C. W. and Bieber, J. W.: 1993, ‘Detection of Steady Magnetic Helicity in Low Frequency IMF Turbulence’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 493–496.
Stoker, P. H.: 1981, ‘Primary Spectral Variations of Cosmic Rays Above 1 GV’,Proc. 17th Int. Cosmic Ray Conf., Paris 3, 193–196.
Stoker, P. H.: 1985, ‘Spectra of Solar Proton Ground Level Events Using Neutron Monitor and Neutron Moderated Detector Recordings’,Proc. 19th Int. Cosmic Ray Conf., La Jolla 4, 114–117.
Stoker, P. H.: 1993, ‘The Solar Proton Flare of 29 September 1989 as Recorded by the South African Neutron Monitors’,Proc. 21st Int. Cosmic Ray Conf., Adelaide 12, 205–209.
Stoker, P. H.: 1993, ‘Cosmic Ray Latitude Distributions at Neutron Monitor and Aircraft Altitudes’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 785–788.
Stoker, P. H. and Louw, P. A.: 1983, ‘The Spectra of Solar Proton Ground Level Events recorded at Sanae’,Proc. 18th Int. Cosmic Ray Conf., Bangalore 4, 181–184.
Stoker, P. H. and Raubenheimer, B. C.: 1985, ‘The Neutron Moderated Detector and Ground Based Cosmic Ray Modulation Studies’,Proc. 19th Int. Cosmic Ray Conf., La Jolla 5, 502–505.
Stoker, P. H. and Makgamathe, S.: 1990, ‘Spectra of Relativistic Solar Proton Ground Level Events Recorded at Sanae, Antarctica’,Astrophys. J. Suppl. 73, 263–268.
Stoker, P. H., Heydenreich, C. E. M., and Bezuidenhout, C. N.: 1993, ‘Ground Level Solar Flare Proton Events Recorded by the Sanae Neutron Monitor Since 1966’,Proc. 23rd Int. Cosmic Ray Conf., Calgary 3, 43–46.
Swinson, D. B. and Shea, M. A.: 1990, ‘The September 29, 1989 Ground Level Event Observed at High Rigidity’,Geophys. Res. Letters 17, 1073–1075.
Valdes-Galicia, J. F.: 1992, ‘Interplanetary Magnetic Field Fluctuations and the Propagation of Cosmic Rays’,Geofisica Internacional 31 (1), 29–40.
Van der Walt, A. J.: 1983, ‘The Calculation of Cosmic Ray Integral and Differential Response Functions and Their Standard Errors’,Proc. 18th Int. Cosmic Ray Conf., Bangalore 10, 287–290.
Van Hollebeke, M. A. I., Ma Sung, L. S., and McDonald, F. B.: 1975, ‘The Variation of Solar Proton Energy Spectra and Size Distribution with Heliolongitude’,Solar Phys. 41, 189–223.
Van Niekerk, F.: 1981, ‘Derivation of Cosmic Ray Differential Response Functions’, M.Sc. Thesis, Potchefstroom University for C.H.E.
Wanner, W. and Wibberenz, G.: 1993, ‘A Study of the Propagation of Solar Energetic Protons in the Inner Heliosphere’,J. Geophys. Res. 98, 3513–3528.
Wanner, W., Wibberenz, G., Jaekel, U., and Kallenrode, M.-B.: 1993,Proc. 18th Int. Cosmic Ray Conf., Calgary 3, 234–237.
Webber, W. R.: 1973, ‘The Energy Spectra of the Cosmic Ray Nucleonic and Electronic Components’,Proc. 13th Int. Cosmic Ray Conf., Denver 5, 3568–3614.
Webber, W. R. and Quenby, J. J.: 1959, ‘On the Derivation of Cosmic Ray Specific Yield Functions,Phil. Mag. 4, 654–664.
Wilson, B. G., Mathews, T., and Johnson, R. H.: 1967, ‘Intercomparison of Neutron Monitors During Solar Flare Increases’,Phys. Rev. Letters 18, 675–676.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Stoker, P.H. Relativistic solar proton events. Space Sci Rev 73, 327–385 (1995). https://doi.org/10.1007/BF00751240
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00751240