J/ApJ/833/196 Cross sections produced by 3He reactions (Murphy+, 2016)
Evidence for enhanced 3He in flare-accelerated particles based on new
calculations of the gamma-ray line spectrum.
Murphy R.J., Kozlovsky B., Share G.H.
<Astrophys. J., 833, 196-196 (2016)>
=2016ApJ...833..196M 2016ApJ...833..196M (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics ; Gamma rays
Keywords: interplanetary medium; Sun: abundances; Sun: chromosphere;
Sun: flares; Sun: particle emission; Sun: X-rays, gamma rays
Abstract:
The 3He abundance in impulsive solar energetic particle (SEP) events
is enhanced up to several orders of magnitude compared to its
photospheric value of [3He]/[4He] = 1-3 x 10-4. Interplanetary
magnetic field and timing observations suggest that these events are
related to solar flares. Observations of 3He in flare-accelerated
ions would clarify the relationship between these two phenomena.
Energetic 3He interactions in the solar atmosphere produce gamma-ray
nuclear-deexcitation lines, both lines that are also produced by
protons and α particles and lines that are essentially unique to
3He. Gamma-ray spectroscopy can, therefore, reveal enhanced levels
of accelerated 3He. In this paper, we identify all significant
deexcitation lines produced by 3He interactions in the solar
atmosphere. We evaluate their production cross sections and
incorporate them into our nuclear deexcitation-line code. We find that
enhanced 3He can affect the entire gamma-ray spectrum. We identify
gamma-ray line features for which the yield ratios depend dramatically
on the 3He abundance. We determine the accelerated 3He/α
ratio by comparing these ratios with flux ratios measured previously
from the gamma-ray spectrum obtained by summing the 19 strongest
flares observed with the Solar Maximum Mission Gamma-Ray Spectrometer.
All six flux ratios investigated show enhanced 3He, confirming
earlier suggestions. The 3He/α weighted mean of these new
measurements ranges from 0.05 to 0.3 (depending on the assumed
accelerated α/proton ratio) and has a <1 x 10-3 probability of
being consistent with the photospheric value. With the improved code,
we can now exploit the full potential of gamma-ray spectroscopy to
establish the relationship between flare-accelerated ions and
3He-rich SEPs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 27 111 Explicit line index
table5.dat 14 7 Unresolved line index
table6.dat 28 2813 Particle energy and cross sections
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 6 F6.3 MeV Line [0.07/7] Line energy
8- 11 A4 --- Target Target name
13- 16 A4 --- Nuc Excited nucleus name
18- 27 A10 --- RxName Reaction name
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Target Target name
9- 14 A6 --- RxName Reaction name
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Reaction name
12- 13 I2 --- Np [9/29] Number of cross sections in Name
15- 20 F6.2 MeV Energy [0.3/270] Particle energy in units of MeV/nucleon
22- 28 F7.2 mbarn CS [0/2482] Cross section at Energy
in milliBarns (10-31m2; barn=10-28m2)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-May-2017