Solar flare gamma-ray line shapes

Werntz, Carl; Kim, Y. E.; Lang, Frederick

doi:10.1086/191471

Cited by 14 publications

(11 citation statements)

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“…Kiener, de Séréville and Tatischeff [20] adopted both methods to reproduce simultaneously line shapes and γ-ray angular distributions of an extensive data set, covering a relatively wide angular and energy range in proton irradiations of carbon and oxygen. The data for the 4.438-MeV line in proton inelastic scattering off 12 C above E p ∼15 MeV could be relatively well described by nuclear reaction calculations with the coupled-channels formalism for the direct component, similar to the findings of Werntz, Lang and Kim [19]. At lower energies, however, the CN component becomes important and the direct reaction mechanism failed to reproduce the data.…”

Section: Introductionsupporting

confidence: 72%

“…data of the Orsay-1997 experiment and calculations are summed with weight factors corresponding to a thick-target interaction probability of an injected beam with energy spectrum F (E p ) ∝ E −3.5 p , as encountered in solar flares.At higher energies, the new data of the Orsay-2002 experiment at E p = 22.5 and 25 MeV and the data of Refs [28,29]. at E p = 23 MeV and 40 MeV, respectively, consolidate the results of Refs [19,20]. pointing out a largely dominating direct reaction component.…”

supporting

confidence: 60%

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Shape and angular distribution of the 4.439-MeV γ -ray line from proton inelastic scattering off C12

Kiener

2019

Phys. Rev. C

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The emission of the 4.438-MeV γ-ray line in proton inelastic scattering off 12 C has been investigated in detail. For this, two independent descriptions of the correlated scattering and emission process have been used, one for the direct reaction mechanism and the other for the compoundnucleus (CN) component. Direct reactions were calculated in the framework of the coupled-channels formalism, while the CN component was described as a superposition of separate resonances with definite spin and parity, treated with the angular momentum coupling theory. Both components were incoherently added and compared to a comprehensive data set on measured line shapes and γ-ray angular distributions in the proton energy range E p = 5.44 -25.0 MeV. In the range E p ∼ 14 -25 MeV, good agreement with data was obtained with a dominating direct reaction component.At lower energy, an important CN component was required to describe line shape and angular distribution data. In general, a good decription of the data could be found for a CN component with spin and parity corresponding to a known nearby resonance. The new calculation was found to improve significantly the agreement with line shape data in particular in the region of dominating CN resonances compared to previous calculations. Based on these results, predictions for line shapes and γ-ray angular distributions up to E p = 100 MeV were made and applied to γ-ray emissions in solar flares and proton radiotherapy. PACS numbers: 23.20En, 24.10Eq, 24.30Gd,25.40Ep * Electronic address: Jurgen.Kiener@csnsm.in2p3.fr

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Section: Introductionsupporting

confidence: 72%

supporting

confidence: 60%

Shape and angular distribution of the 4.439-MeV γ -ray line from proton inelastic scattering off C12

Kiener

2019

Phys. Rev. C

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“…2.11). The shape of the narrow γ -ray lines ultimately depends on the angular distribution and spectrum in the interaction site, the assumed α/p ratio, and the viewing angle of the observer (see, e.g., Ramaty and Crannell 1976;Ramaty et al 1979;Murphy et al 1988;Werntz et al 1990;Lang and Werntz 1991;Kiener et al 2001;.…”

Section: Alpha Particlesmentioning

confidence: 99%

Properties of Energetic Ions in the Solar Atmosphere from γ-Ray and Neutron Observations

2011

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Gamma-rays and neutrons are the only sources of information on energetic ions present during solar flares and on properties of these ions when they interact in the solar atmosphere. The production of γ -rays and neutrons results from convolution of the nuclear cross-sections with the ion distribution functions in the atmosphere. The observed γ -ray and neutron fluxes thus provide useful diagnostics for the properties of energetic ions, yielding strong constraints on acceleration mechanisms as well as properties of the interaction sites. The problem of ion transport between the accelerating and interaction sites must also be addressed to infer as much information as possible on the properties of the primary ion accelerator. In the last couple of decades, both theoretical and observational developments have led to substantial progress in understanding the origin of solar γ -rays and neutrons. This chapter reviews recent developments in the study of solar γ -rays and of solar neutrons at the time of the RHESSI era. The unprecedented quality of the RHESSI data reveals γ -ray line shapes for the first time and provides γ -ray images. Our previous understanding of the properties of energetic ions based on measurements from the former solar cycles is also summarized. The new results-obtained owing both to the gain in spectral resolution (both with RHESSI and with the non solar-dedicated INTEGRAL/SPI instrument) and to the pioneering imaging technique in the γ -ray domain-are presented in the context of this previous knowledge. Still open questions are emphasized in the last section of the chapter and future perspectives on this field are briefly discussed.

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“…They described how these angular distributions can be dis-tinguished from one another using gamma-ray line measurements made at different heliocentric angles, especially when made with a high-resolution spectrometer. Based on an optical model with parameters determined by accelerator particle data, Werntz, Lang, & Kim (1990) developed a computer code that calculated the shapes of the 12 C and 16 O lines from inelastic collisions of protons. They showed representative spectra for fan beams, downward beams, and isotropic interacting particle distributions for both thick and thin targets.…”

Section: Introductionmentioning

confidence: 99%

Directionality of Solar Flare–accelerated Protons and α‐Particles from γ‐Ray Line Measurements

Share¹,

Murphy²,

Kiener³

et al. 2002

ApJ

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The energies and widths of γ-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 12 C, 16 O, and 20 Ne 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 12 C 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.

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Solar flare gamma-ray line shapes

Cited by 14 publications

References 0 publications

Shape and angular distribution of the 4.439-MeV γ -ray line from proton inelastic scattering off C12

Shape and angular distribution of the 4.439-MeV γ -ray line from proton inelastic scattering off C12

Properties of Energetic Ions in the Solar Atmosphere from γ-Ray and Neutron Observations

Directionality of Solar Flare–accelerated Protons and α‐Particles from γ‐Ray Line Measurements

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