Nuclear Deexcitation Gamma Ray Lines from Accelerated Particle Interactions |
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Ronald Murphy Submitted: 2002-03-13 13:01
Total cross sections for the production of gamma-ray lines from nuclear deexcitation as a function of the projectile energy are evaluated and presented. Included are proton and α reactions with He, C, N, O, Ne, Mg, Al, Si, S, Ca and Fe. Such functions are essential for interpretation of gamma-ray line observations of astrophysical sites which contain large fluxes of energetic particles such as solar flares, the Earth's atmosphere, planetary atmospheres and surfaces, the interstellar medium and galactic nebulae.
Authors: Kozlovsky, B., Murphy, R. J., & Ramaty, R.
Projects:
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Publication Status: Astrophysical Journal Supplement (accepted)
Last Modified: 2002-10-28 14:21
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Accelerated Particle Composition and Energetics and Ambient Abundances from Gamma-Ray Spectroscopy of the 1991 June 4 Solar Flare |
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Ronald Murphy Submitted: 1999-11-08 18:02
The Oriented Scintillation Spectrometer Experiment (OSSE) on board the COMPTON
Gamma Ray Observatory observed the 1991 June 4 X12+ solar flare, one of the most
intense nuclear gamma-ray line flares observed to date. Using these OSSE
observations, we have derived time profiles of the various components of
gamma-ray emission and obtained information about the accelerated particle
spectra and composition and about the ambient plasma at the flare site. The main
results are: (1) the nuclear reactions associated with the impulsive phase of
the flare continued for at least 2 hours and resulted from ions that were
probably continuously accelerated rather than impulsively accelerated and
trapped; (2) the total energy in these accelerated ions exceeded the energy in
>0.1 MeV electrons; (3) the accelerated α proton ratio was closer to 0.5
than to 0.1; (4) there is evidence for a decrease of the accelerated heavy
ion-to-proton ratio as the flare progressed (5) there is evidence for a temporal
change in the composition of the flare plasma; (6) the ratio of electron
bremsstrahlung to the flux in narrow gamma-ray lines decreased as the flare
progressed; (7) the high-energy (>16 MeV) component of the electron spectrum was
much more impulsive than the lower-energy ~MeV component; (8) a model-dependent
upper limit of 2.3 x 10-5 was obtained for the photospheric 3He/H abundance
ratio; and (9) energetic ions may have been present for several hours prior to
and following the impulsive phase of the flare.
Authors: R.J. Murphy, G.H. Share, J.E. Grove, W.N. Johnson, R.L. Kinzer, J.D. Kurfess, M.S. Strickman, and G.V. Jung
Projects:
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Publication Status: Ap. J., 490, 883 (1997)
Last Modified: 2002-10-29 05:56
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