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Delayed X- and Gamma-Ray Line Emission from Solar Flare Radioactivity

Delayed X- and Gamma-Ray Line Emission from Solar Flare Radioactivity. V. Tatischeff, B. Kozlovsky, J. Kiener and R. J. Murphy ApJS, submitted. Proposed by Ramaty & Mandzhavidze (2000, IAU Symp.) size and development of the radioactive patch

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Delayed X- and Gamma-Ray Line Emission from Solar Flare Radioactivity

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  1. Delayed X- and Gamma-Ray Line Emission from Solar Flare Radioactivity V. Tatischeff, B. Kozlovsky, J. Kiener and R. J. Murphy ApJS, submitted • Proposed by Ramaty & Mandzhavidze (2000, IAU Symp.) • size and development of the radioactive patch • mixing and transport processes in the solar atmosphere • the most promising delayed line is at 847 keV from 56Codecay

  2. Selection of the Radioisotopes • 10 min <T1/2 < 77 days • 21 b+-emitters (KLR87 + KMS04) + 7Be, 24Na, 56Mn, 58Com • Updated cross sections for the production of 34Clm, 52Mng, 52Mnm, 55Co, 56Co, 57Ni, 58Cog, 60Cu and61Cu by p, a and 3He reactions

  3. TALYS calculations Data: Michel et al. (1997) x10-2 x10-4 x10-6 Radioisotope Production Cross Sections • Experimental reaction data from EXFOR http://www.nndc.bnl.gov/exfor/ + Theoretical estimates from EMPIRE-II (version 2.19), TALYS (version 0.64), and the "Silberberg & Tsao" code above ~250 MeV (cosmic-ray physics)

  4. Radioisotope Production Yields • Thick target interaction model with nuclear destruction and catastrophic energy loss (e. g. pion production) of the fast ions (interactions between fast and ambient heavy ions are negligible) • Power law source spectrum up to 1 GeV/nucleon, with s=3.5, 2 and 5 • Impulsive-flare composition from SEP, with a/p=0.5 and 3He/a=0.5

  5. * Delayed line emission 30 min after the end of the flare • Unexpected strong lines at 1434 keV from 52Mnm, 1332 and 1792 keV from 60Cu, 6.92 (Co Ka) from 58Com (Ex=25 keV) + 57Ni, 2127 keV from 34Clm... • Normalized to a fluence of 300 g cm-2 emitted in the sum of the 4.4 and 6.1 MeV prompt narrow lines (2003 Oct. 28 flare)

  6. The experimental proof

  7. * Delayed line emission 3 h after the flare • The strongest line after that at 511 keV can be the neutral Co Ka line • Photoelectric attenuation: at solar depths of 10-3–10-1 g cm-2 (low chromosphere), the optical depths of 6.92 keV X-rays are ~ 10-3–10-1 • X-ray imaging of the radioactive patch ? • Normalized to a fluence of 300 g cm-2 emitted in the sum of the 4.4 and 6.1 MeV prompt narrow lines (2003 Oct. 28 flare)

  8. * Delayed line emission 3 days after the flare Time dependence of the 511 keV line • From ~1 to ~14 hours, the main source of the positrons is18F, which can be mainly produced by 16O(3He,p)18F • Measurement of the 511 keV decay curve can provide the accelerated 3He abundance

  9. Reames et al. (1994) H/4He ? 3He/4He Reames (1995) The influence of the accelerated ion composition • SEP composition for fast C and heavier elements relative to a-particles, but with a/p=0.5 ( a–a line in g-ray flares, SM97...) • Strong enhancement of the fast heavy elements, with e.g. AFe/Ap=137 nFe/nH • The delayed lines will measure this enrichment

  10. … an artist’s Cosmic Vision The Gamma-Ray Imager From J. Knödlseder, ESLAB Symposium 2005

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