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Characteristics of Sustained >100 γ-ray Emission Associated with Solar Flares  

Gerald Share   Submitted: 2017-10-28 14:08

We characterize and provide a catalog of thirty >100 MeV sustained γ-ray emission (SGRE) events observed by Fermi LAT. These events are temporally and spectrally distinct from the associated solar flares. Their spectra are consistent with decay of pions produced by >300 MeV protons and are not consistent with electron bremsstrahlung. SGRE start times range from CME onset to two hours later. Their durations range from about four minutes to twenty hours and appear to be correlated with durations of >100 MeV SEP proton events. The >300 MeV protons producing SGRE have spectra that can be fit with power laws with a mean index of ∼4 and RMS spread of 1.8. γ-ray line measurements indicate that SGRE proton spectra are steeper above 300 MeV than they are below 300 MeV. The number of SGRE protons >500 MeV is on average about ten times more than the number in the associated flare and about fifty to one hundred times less than the number in the accompanying SEP. SGRE can extend tens of degrees from the flare site. Sustained bremsstrahlung from MeV electrons was observed in one SGRE event. Flare >100 keV X-ray emission appears to be associated with SGRE and with intense SEPs. From this observation, we provide arguments that lead us to propose that sub-MeV to MeV protons escaping from the flare contribute to the seed population that is accelerated by shocks onto open field lines to produce SEPs and onto field lines returning to the Sun to produce SGRE.

Authors: G. H. Share, R. J. Murphy, A. K. Tolbert, B. R. Dennis, S. M. White, R. A. Schwartz, and A. J. Tylka
Projects: Fermi/LAT

Publication Status: Submitted to Astrophysical Journal Supplement
Last Modified: 2017-11-01 12:23
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Comment on ``Detection and characterization of 0.5-8 MeV neutrons near Mercury: Evidence for a solar origin"  

Gerald Share   Submitted: 2014-09-25 13:24

We argue that the hour-long neutron transient detected by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) Neutron Spectrometer beginning at 15:45 UT on 2011 June 4 is due to secondary neutrons from energetic protons interacting in the spacecraft. The protons were probably accelerated by a shock that passed the spacecraft about thirty minutes earlier. We reach this conclusion after a study of data from the MESSENGER neutron spectrometer, gamma-ray spectrometer, X-ray Spectrometer, and Energetic Particle Spectrometer, and from the particle spectrometers on STEREO A. Our conclusion differs markedly from that given by Lawrence et al. (2014} who claimed that there is "strong evidence" that the neutrons were produced by the interaction of ions in the solar atmosphere. We identify significant faults with the authors' arguments that led them to that conclusion.

Authors: Gerald H. Share, Ronald J. Murphy, Allan J. Tylka, Brian R. Dennis, and James M. Ryan
Projects: STEREO

Publication Status: Submitted to Journal of Geophysical Research (Space Physics)
Last Modified: 2014-09-25 15:57
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Fermi Detection of gamma-ray emission from the M2 Soft X-ray Flare on 2010 June 12  

Gerald Share   Submitted: 2011-12-21 13:51

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: Ackerman et al.; Corresponding authors: M. Briggs, D. Gruber, F. Longo, N. Omodei, and G. Share
Projects: None

Publication Status: Accepted for Publication in ApJ
Last Modified: 2011-12-22 13:40
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Physics of Solar Neutron Production: Questionable Detection of Neutrons from the 2007 December 31 Flare  

Gerald Share   Submitted: 2010-12-23 20:44

Spacecraft observations in the inner heliosphere offer the first opportunity to measure 1-10 MeV solar neutrons. We discuss the cross sections for neutron production in solar flares and calculate the escaping neutron spectra for mono-energetic and power-law particle spectra at the Sun and at the distance (0.48 AU) and observation angle of MESSENGER at the time of its reported detection of low-energy solar neutrons associated with the 2007 December 31 solar flare. We detail solar physics concerns about this detection: 1. the inferred number of accelerated protons at the Sun for this modest M2-class flare would have been 10 times larger than any flare observed to date and 2. the implied energy in accelerated ions would have been 50 to 104 times what we would expect based on the observed energy in non-thermal electrons and the energy in the thermal X-ray plasma. We find that there is no compelling evidence for a high electron/proton ratio in the solar energetic particle (SEP) event raising concerns that the neutron counts came mostly from SEP ion interactions in the spacecraft; this concern is supported by the similarity of the SEP and neutron count rates. The MESSENGER team made detailed calculations of neutron production from SEP protons. However, if interactions <30 MeV had been included in their calculations and the carbon spacecraft structure were a significant source of secondary neutrons we estimate that SEP proton and α particle interactions could account for the observed fast neutron rate. This is due to 13C that has a 3 MeV proton threshold for neutron production and is exothermic for α particle interactions.

Authors: Gerald H. Share, Ronald J. Murphy, Allan J. Tylka, Benz Kozlovsky, James M. Ryan, and Chul Gwon
Projects:

Publication Status: Accepted for publication JGR Space Physics, Copyright 2011 AGU. Further reproduction or electronic distribution is not permitted.
Last Modified: 2010-12-31 07:00
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GLAST Solar System Science  

Gerald Share   Submitted: 2007-04-25 11:49

We briefly discuss GLAST?s capabilities for observing high-energy radiation from various energetic phenomena in our solar system. These emissions include: bremsstrahlung, nuclear-line and pion-decay gamma-radiation, and neutrons from solar flares; bremsstrahlung and pion-decay gamma radiation from cosmic-ray interactions with the Sun, the Moon, and the Earth's atmosphere; and inverse Compton radiation from cosmic-ray electron interactions with sunlight.

Authors: Gerald H. Share and Ronald J. Murphy
Projects: RHESSI

Publication Status: To be published in AIP Proceedings of the First GLAST Science Workshop held at Stanford University, Feb. 5-8, 2007
Last Modified: 2007-04-25 11:52
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Radiation from Flare-Accelerated Particles Impacting the Sun  

Gerald Share   Submitted: 2005-03-24 08:32

We discuss how remote observations of gamma-ray lines and continuum provide information on the population of electrons and ions that are accelerated at the flare site. The radiation from these interactions also provides information on the composition of the flaring atmosphere. We focus our discussion on recent RHESSI observations and archival observations made by SMM and Yohkoh.

Authors: Gerald H. Share and Ronald J. Murphy
Projects: RHESSI

Publication Status: Submitted to AGU Monograph, 2004 Chapman Conference, 'Solar Eruptions and Energetic Particles', ed. N. Gopalswamy
Last Modified: 2005-03-24 08:32
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RHESSI e+  

Gerald Share   Submitted: 2004-10-29 11:28

RHESSI has measured the positron-electron annihilation line and continuum in three solar flares: 2002 July 23, 2003 October 28, and 2003 November 2. The 511 keV line was broad (~4–8 keV) in all three flares, consistent with annihilations in an ambient ionized medium at temperatures above 105 K. The measured continuum from positronium and from Compton scattering was unobservable, with the exception of the first 4 minutes of the October 28 flare observation; this indicates that the density at which most annihilations occurred was greater than ~1014 H cm-3. The width of the line narrowed in 2 minutes to ~1 keV late in the October 28 flare, consistent with RHESSI has measured the positron-electron annihilation line and continuum in three solar flares: 2002 July 23, 2003 October 28, and 2003 November 2. The 511 keV line was broad (~4–8 keV) in all three flares, consistent with annihilations in an ambient ionized medium at temperatures above 105 K. The measured continuum from positronium and from Compton scattering was unobservable, with the exception of the first 4 minutes of the October 28 flare observation; this indicates that the density at which most annihilations occurred was greater than ~1014 H cm-3. The width of the line narrowed in 2 minutes to ~1 keV late in the October 28 flare, consistent with annihilation in ionized H <104 K and >1015 cm-3. There is evidence for a similar decrease in line width late in the November 2 flare. These observations suggest a highly dynamic flaring atmosphere at chromospheric densities that can reach transition-region temperatures, then cool to less than 104 K in minutes while remaining highly ionized. Although the energy contained in high-energy accelerated particles may have been enough to heat the plasma, the rate of deposition is not correlated with the temperature determined by the 511 keV line width, and this raises questions about the energy source.

Authors: Gerald H. Share, Ronald J. Murphy, David M. Smith, Richard A. Schwartz, and Robert P. Lin
Projects: RHESSI

Publication Status: published ApJ November 10, 615, L169
Last Modified: 2004-10-29 11:28
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Solar Gamma-Ray Line Spectroscopy - Physics of a Flaring Star  

Gerald Share   Submitted: 2004-06-15 13:13

We discuss how gamma-ray spectroscopy provides information about the acceleration and transport of electrons and ions in solar flares, and their interaction with the solar atmosphere. Temporal studies illuminate differences in the acceleration and transport of electrons and ions. Nuclear line studies reveal the elemental abundance, density, and temperature of the ambient solar atmosphere; and the spectrum, composition, and directionality of the accelerated ions.

Authors: G.H. Share and R.J. Murphy
Projects: RHESSI

Publication Status: in Stars as Suns: Activity, Evolution and Planets, ASP Conf. Series 219, ed. A. Benz & A. Dupree, in press July 2004
Last Modified: 2004-06-15 13:13
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High-Resolution Observation of the Solar Positron-Electron Annihilation Line  

Gerald Share   Submitted: 2003-06-03 13:29

RHESSI has observed the positron-electron annihilation line at 511 keV produced during the 2002 July 23 solar flare. The shape of the line is consistent with annihilation in two vastly different solar environments. It can be produced by formation of positronium by charge exchange in flight with hydrogen in a quiet solar atmosphere at a temperature of ~6000 K. However, the measured upper limit to the 3 gamma/2 gamma ratio (ratio of annihilation photons in the positronium continuum to the number in the line) is only marginally consistent with what is calculated for this environment. The annihilation line can also be fit by a thermal Gaussian having a width of 8.1 ± 1.1 keV (FWHM), indicating temperatures of ~4 - 7 × 105 K. The measured 3 gamma/2 gamma ratio does not constrain the density when the annihilation takes place in such an ionized medium, although the density must be high enough to slow down the positrons. This would require the formation of a substantial mass of atmosphere at transition-region temperatures during the flare.

Authors: G.H. Share, R.J. Murphy, J.G. Skibo, D.M. Smith, H.H. Hudson, R.P. Lin, A.Y. Shih, B.R. Dennis, and R.A. Schwartz
Projects: None

Publication Status: Ap J Letters RHESSI issue -- in press
Last Modified: 2003-06-03 13:29
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Directionality of Flare-Accelerated Alpha Particles at the Sun  

Gerald Share   Submitted: 2003-06-03 13:26

RHESSI has observed the 7Be and 7Li gamma-ray lines from fusion of accelerated α particles with ambient helium produced during the 2002 July 23 solar flare that erupted at a heliocentric angle of 73°. This is the first observation of the lines with a germanium spectrometer. We have fit the measured lines with calculated shapes for different energy and angular distributions for the interacting α particles. A particle distribution from saturated pitch-angle scattering in the corona provides the best fit, but isotropic, downward-isotropic, or fan-beam distributions also provide acceptable fits. We can rule out a downward-beamed distribution with 99.99% confidence. RHESSI measurements of other Doppler-shifted nuclear de-excitation lines are consistent with a forward isotropic distribution of interacting particles in a magnetic loop tilted by ~40° from the normal to the solar surface toward Earth. Such a distribution is also consistent with the α 4He line shape with ~15% con dence.

Authors: G.H. Share, R.J. Murphy, D.M. Smith, R.P. Lin, B.R. Dennis, and R.A. Schwartz
Projects: RHESSI

Publication Status: ApJ Letters RHESSI issue -- in press
Last Modified: 2003-06-03 13:26
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RHESSI Observation of Atmospheric Gamma Rays from Impact of Solar Energetic Particles on 21 April 2002  

Gerald Share   Submitted: 2002-10-28 14:27

The RHESSI high-resolution spectrometer detected gamma-ray lines and continuum emitted by the earth's atmosphere during impact of solar energetic particles in the south polar region from 1600-1700 hours UT on 21 April 2002. The particle intensity at the time of the observation was a factor of 10 - 100 weaker than previous events when gamma-rays were detected by other instruments. This is the first high-resolution observation of atmospheric gamma-ray lines produced by solar energetic particles. De-excitation lines were resolved that, in part, come from 14N at 728, 1635, 2313, 3890 and 5106 keV, and the 12C spallation product at ~4439 keV. Other unresolved lines were also detected. We provide best-fit line energies and widths and compare these with moderate resolution measurements by SMM of lines from an SEP event and with high-resolution measurements made by HEAO 3 of lines excited by cosmic rays. We use line ratios to estimate the spectrum of solar energetic particles that impacted the atmosphere. The 21 April spectrum was significantly harder than that measured by SMM during the 20 October 1989 shock event; it is comparable to that measured by Yohkoh on 15 July 2000. This is consistent with measurements of 10 - 50 MeV protons made in space at the time of the gamma-ray observations.

Authors: Gerald H. Share, Ronald J. Murphy, B.R. Dennis, R.A. Schwartz, A.K. Tolbert, R.P. Lin, & D.M. Smith
Projects:

Publication Status: Solar Physics (in press)
Last Modified: 2002-10-28 14:27
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Directionality of Solar Flare Accelerated Protons and Alpha Particles from Gamma-Ray Line Measurements  

Gerald Share   Submitted: 2002-03-13 09:55

The energies and widths of gamma-ray lines emitted by ambient nuclei excited by flare-accelerated protons and α particles provide information on the ions directionality and spectra, and on the characteristics of the interaction region. We have measured the energies and widths of strong lines from de-excitations of 12C, 16O, and 20Ne in solar flares as a function of heliocentric angle. The line energies from all three nuclei exhibit ~1% redshifts for flares at small heliocentric angles, but are not shifted near the limb. The lines have widths of ~3% FWHM. We compare the 12C line measurements for flares at five different heliocentric angles with calculations for different interacting-particle distributions. A downward isotropic distribution (or one with a small upward component) provides a good fit to the line measurements. An angular distribution derived for particles that undergo significant pitch angle scattering by MHD turbulence in coronal magnetic loops provides comparably good fits.

Authors: G. H. Share, R. J. Murphy, J. Kiener and N. de Sereville
Projects:

Publication Status: Accepted for publication in Ap. J. (July 2002)
Last Modified: 2002-10-28 14:59
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Gamma-Ray Line Observations of the 2000 July 14 Flare and SEP Impact on the Earth  

Gerald Share   Submitted: 2001-05-17 07:45

The HXS and GRS detectors on Yohkoh observed the 2000 July 14, X5.7 flare, beginning at ~10:20 UT, ~4 m before the peak in soft X rays. The hard X rays and gamma rays peaked ~3 m later at ~10:27 UT. Solar gamma-ray emission lasted until ~10:40 UT. Impact of high-energy ions at the Sun is revealed by the gamma-ray lines from neutron capture, annihilation radiation and de-excitation that are visible above the bremsstrahlung continuum. From measurement of these lines we find that the flare-averaged spectrum of accelerated protons is consistent with a power law >10 MeV with index 3.14 ± 0.15 and flux 1.1 X 1032 MeV^-1 at 10 MeV. We estimate that there were ~1.5 X 1030 erg in accelerated ions if the power law extended without a break down to 1 MeV; this is about 1% of the energy in electrons >20 keV from measurements of the hard X rays. We find no evidence for spectral hardening in the hard X rays that has been suggested as a predictor for the occurrence of solar energetic particle (SEP) events. This was the third largest proton event above 10 MeV since 1976. The GRS and HXS also observed gamma-ray lines and continuum produced by the impact of SEP on the Earth's atmosphere beginning about 13 UT on July 14. These measurements show that the SEP spectrum softened considerably over the next 24 hours. We compare these measurements with proton measurements in space.

Authors: G.H. Share, R.J. Murphy, A.J. Tylka, R.A. Schwartz, M., Yoshimori, K. Suga, S. Nakayama, H. Takeda
Projects:

Publication Status: Solar Physics (submitted)
Last Modified: 2002-10-28 14:59
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Correlation of Upper-Atmospheric 7Be with Solar Energetic Particle Events  

Gerald Share   Submitted: 2001-02-26 12:04

A surprisingly large concentration of radioactive 7Be was observed in the upper atmosphere at altitudes above 320 km on the LDEF satellite that was recovered in January 1990. We report on follow-up experiments on Russian spacecraft at altitudes of 167 to 370 km during the period of 1996 to 1999, specifically designed to measure 7Be concentrations in low earth orbit. Our data show a significant correlation between the 7Be concentration and the solar energetic proton fluence at Earth, but not with the overall solar activity. During periods of low solar proton fluence, the concentration is correlated with the galactic cosmic ray fluence. This indicates that spallation of atmospheric N by both solar energetic particles and cosmic rays is the primary source of 7Be in the ionosphere.

Authors: Phillips, G. W. ; Share, G. H. ; King, S. E. ; August, R. A. ; Tylka, A. J. ; Adams, J. H., Jr. ; Panasyuk, M. I. ; Nymmik, R. A. ; Kuzhevskij, B. M. ;
Projects:

Publication Status: Geophys. Res. Lett. Vol. 28 , No. 5 , p. 939 (2001)
Last Modified: 2002-10-28 15:00
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Atmospheric gamma rays from solar energetic particles and cosmic rays penetrating the magnetosphere  

Gerald Share   Submitted: 2001-02-21 07:20

We detail observations of gamma rays produced by interactions of cosmic rays and solar-energetic particles on the Earth's atmosphere. The Solar Maximum Mission (SMM) spectrometer accumulated the quiescent atmospheric spectrum over its full 9-year lifetime and our analysis revealed 20 resolved line features. We compare this spectrum with one collected on October 20, 1989, when SMM observed gamma rays produced by shock-accelerated protons that impacted the atmosphere in the polar region following an intense solar flare and coronal mass ejection. Observed nuclear-line intensities increased by over a factor of 50 during this event. Because this event was on the horizon and subtended a limited solid angle as viewed from SMM, the local increase was several times higher. We compare the gamma ray line energies, widths, and intensities from the solar event and quiescent atmospheric spectra and discuss their identifications. From this comparison we confirm direct observations that the solar proton spectrum is considerably softer than the spectrum of cosmic rays. Extension of an existing code for calculating solar gamma ray lines will provide information on the spectra of the protons reaching the Earth's atmosphere and thus on their transport through the magnetosphere. Broad spectral features found in the spectra are likely to be caused by a multitude of unresolved lines excited by neutron capture in the instrument, spacecraft, and Earth's atmosphere.

Authors: Gerald H. Share and Ronald J. Murphy
Projects:

Publication Status: Journal of Geophysical Research - Space Physics - Vol. 106, No. A1, p. 77
Last Modified: 2002-10-28 15:00
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Limits on Radiative Capture Gamma-Ray Lines and Implications for Energy Content in Flare-Accelerated Protons  

Gerald Share   Submitted: 2001-02-20 10:12

Measurements of radiative capture gamma-ray lines can provide information on both the energy content of nonthermal protons below 1 MeV and the temperature in the region where they interact. We have derived upper limits on the fluences in three proton capture lines of 12C and 13C in the flare-averaged gamma-ray spectrum from 19 X-class flares observed with the Solar Maximum Mission (SMM). The most significant limit comes from the 2.37 MeV line that is excited by 0.46 MeV protons. We estimate an upper limit on the energy content in the accelerated protons by extrapolating the power law spectrum derived at higher energies down to the resonant energy. The derived upper limit on the temperature, 5-10 times 107 K, is higher than measured in the flaring region with other techniques, even for this optimistic energy content. It is possible that NASA's High Energy Solar Spectroscopic Imager (HESSI) will be sensitive enough to detect the 2.37 MeV line if temperatures exceed 2 times 107 K.

Authors: Share, G.H., Murphy, R.J.,and Newton, E. K.
Projects:

Publication Status: Solar Physics (In press)
Last Modified: 2002-10-28 15:01
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Gamma Ray Spectroscopy in the Pre-HESSI Era  

Gerald Share   Submitted: 2000-02-04 17:04

HESSI will provide the high-resolution gamma-ray spectroscopy not available in early missions. In spite of these spectral limitations the experiments on SMM, Yohkoh, GRANAT and the Compton Gamma Ray Observatory have provided data for fundamental discoveries over the past decades relating to particle acceleration, transport and energetics in flares and to the ambient abundance of the corona and chromosphere. These include: 1) enhancement in the concentration of low FIP elements where accelerated particles interact, 2) a new line ratio for deriving the spectra of accelerated particles <10 MeV, 3) energies in accelerated ions that exceed those in electrons for some flares, 4) a highly variable ion to electron ratio during flares, 5) concentration of 3He in flare-accelerated particles enhanced by a factor of >1000 over its photospheric value, 6) an accelerated α p ratio >0.1 in several flares and evidence for high ambient 4He in some flares, 7) measurements of the positronium fraction and a temperature-broadened 511 keV line width, 8) new information on the directional- directionality of electrons, protons, and heavy ions and/or on the homogeneity of the interaction region, and 9) the spectrum of broadened gamma-ray lines emitted by accelerated heavy ions that indicates Fe enhancements consistent with those observed in solar energetic particles. We discuss some of these and also new developments.

Authors: G. H. Share and R. J. Murphy
Projects:

Publication Status: Submitted to the HESSI Workshop Proceedings
Last Modified: 2002-10-28 15:02
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Gamma-Ray Measurement of Energetic Heavy Ions at the Sun  

Gerald Share   Submitted: 1999-11-08 18:02

We have derived the gamma-ray line spectra from accelerated heavy ions at the Sun in data from the Solar Maximum Mission (SMM) Gamma Ray Spectrometer and the Compton Gamma Ray Observatory (CGRO) OSSE instrument. These lines are Doppler-b- Doppler-broadened and, perhaps shifted, reflecting the transport of the particl- particles. They provide the only source of information on the composition of accelerated heavy ions at the Sun. Analysis of the integrated spectrum from 19 flares suggests that accelerated Fe is enhanced by about a factor of five over its ambient abundance. Future measurements with CGRO can be compared with observations of solar energetic particles by ACE.

Authors: G.H. Share and R.J. Murphy
Projects:

Publication Status: 26th ICRC Proceedings, Salt Lake City, UT, Vol. 6, p. 13 (1999)
Last Modified: 2002-10-28 15:06
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Atmospheric Gamma-Ray Lines Produced by Cosmic Rays and Solar Energetic Particles  

Gerald Share   Submitted: 1999-11-08 14:01

We describe observations of atmospheric gamma rays produced by interactions of both cosmic rays and solar-energetic particles. The quiescent atmospheric spectrum produced by cosmic radiation was accumulated by the Solar Maximum Mission (SMM) spectrometer over its full 9-year lifetime. These observations are compared with a remarkable event observed by the spectrometer at about 1600 UT on 1989 October 20 during an intense solar energetic particle event at the Earth. The particle event followed an intense X-ray flare and coronal mass ejection that had occurred on the previous day. Twenty-three line features were identified from this event and twenty four were observed from the quiescent atmosphere. We compare the energies, widths and intensities of the different lines in both these spectra and discuss their origins.

Authors: G.H. Share, R.J. Murphy and E. Rieger
Projects:

Publication Status: 26th ICRC Proceedings, Salt Lake City, UT, Vol. 7, p. 329 (1999)
Last Modified: 2002-10-28 15:05
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Abstracts by Author
Characteristics of Sustained >100 γ-ray Emission Associated with Solar Flares
Comment on ``Detection and characterization of 0.5--8 MeV neutrons near Mercury: Evidence for a solar origin"
Fermi Detection of gamma-ray emission from the M2 Soft X-ray Flare on 2010 June 12
Physics of Solar Neutron Production: Questionable Detection of Neutrons from the 2007 December 31 Flare
GLAST Solar System Science
Radiation from Flare-Accelerated Particles Impacting the Sun
RHESSI e+
Solar Gamma-Ray Line Spectroscopy - Physics of a Flaring Star
High-Resolution Observation of the Solar Positron-Electron Annihilation Line
Directionality of Flare-Accelerated Alpha Particles at the Sun
RHESSI Observation of Atmospheric Gamma Rays from Impact of Solar Energetic Particles on 21 April 2002
Directionality of Solar Flare Accelerated Protons and Alpha Particles from Gamma-Ray Line Measurements
Gamma-Ray Line Observations of the 2000 July 14 Flare and SEP Impact on the Earth
Correlation of Upper-Atmospheric 7Be with Solar Energetic Particle Events
Atmospheric gamma rays from solar energetic particles and cosmic rays penetrating the magnetosphere
Limits on Radiative Capture Gamma-Ray Lines and Implications for Energy Content in Flare-Accelerated Protons
Gamma Ray Spectroscopy in the Pre-HESSI Era
Gamma-Ray Measurement of Energetic Heavy Ions at the Sun
Atmospheric Gamma-Ray Lines Produced by Cosmic Rays and Solar Energetic Particles

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