Delayed X and GammaRay Line Emission from Solar Flare Radioactivity

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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 56Co decay

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Selection of the Radioisotopes

• 10 min ltT1/2 lt 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 and 61Cu by p, a and 3He reactions

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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)

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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 s3.5, 2 and 5
• Impulsive-flare composition from SEP, with
  a/p0.5 and 3He/a0.5

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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 (Ex25 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)

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The experimental proof
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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
  10-310-1 g cm-2 (low chromosphere), the optical
  depths of 6.92 keV X-rays are 10-310-1
• 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)

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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 is 18F, which can be mainly produced by
  16O(3He,p)18F
• Measurement of the 511 keV decay curve can
  provide the accelerated 3He abundance

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The influence of the accelerated ion composition

• SEP composition for fast C and heavier elements
  relative to a-particles, but with a/p0.5 (? aa
  line in g-ray flares, SM97...)
• Strong enhancement of the fast heavy elements,
  with e.g. AFe/Ap137 nFe/nH
• The delayed lines will measure this enrichment

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The Gamma-Ray Imager
an artists Cosmic Vision
From J. Knödlseder, ESLAB Symposium 2005