Transcript Cosmic rays in solar system

Cosmic rays in solar system
By: Tiva Sharifi
Cosmic ray
The earth atmosphere is bombarded with
the energetic particles originating from the
outer space called cosmic rays
1) Galactic cosmic rays (GCR)
2) Solar cosmic rays (SCR)
cosmic rays sources
Large flares produce
most of the SCR particles
emitted during 11-year
solar cycle
solar event lasts at least for
a couple of days…….. time
averaged flux of SCR is
higher than the GCR flux.
Nature of cosmic rays
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Proton (89%)
Alpha particles (10%)
Heavy (z=3 to 90) nuclei (1%)
GCR particles; high energies and low flux
SCR particles; low energies (<300MeV) and
high flux
Cosmic ray interactions with
magnetic field
Deflection!
GCR encounter with galactic, interstellar, solar
and the earth magnetic field
Impossible to realize the source of GCR via
their incoming direction
Sun and Earth magnetic field
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Solar magnetic field variations
Long term (solar cycle)
Short term (magnetic clouds originating from
solar flares)
The earth magnetic field variations
Solar wind
Cosmic ray interactions with
matter
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Based on the energy, charge and mass of the
energetic particle the nature of interaction
process and its products can be estimated
It is on the surface in which the cosmic ray
records can be readily determined
Cosmic ray interactions with
matter
Radiation
Solar cosmic
rays
Galactic
cosmic rays
Energies
(MeV
nucleon-1)
Mean flux
(particles
cm-1s-1)
Effective
depth (cm)
Protons and
helium nuclei
5-100
~ 100
0-2
Heavier
nuclei
1-50
~1
0-0.1
Protons and
helium nuclei
100-3000
3
0-100
Heavier
nuclei
~100
0.03
0-10
particles
Nuclide production
Atmospheric cascade:
A “primary” cosmic ray particle
strike an atom in Earth's
atmosphere, this collision
results in the production of one
or more "secondary" cosmic ray
particle are
The Earth
Nuclide production
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The nuclear by products of the cascade can
reach Earth's surface if the primary cosmic
ray has energy greater than 500 million
electron volts (neutrons and pions)
The low energy solar protons and alpha
particles stop very close to the surface of the
atmosphere by ionization energy loss
The Earth
Flux of the cosmic ray
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The earth magnetic field
The solar wind
either decelerate
or exclude the particles
with energies below 1GeV
Earth weather
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In the lower atmosphere,
Muons ionize the gas molecules.
A positive ion is created
The released electron is captured (creation
negative ion or recombination)
The ionization and recombination effect is
balanced
the negative ions are more mobile which
results in an electric field (100 V/m).
Earth weather
Thunderstorm
 Separation of positive
and negative ions
forms an electric field.
Discharge (lightening)
happens if the electric
field is high enough.
 Cosmic rays have a
direct influence on
earth weather
C , the most famous
cosmogenic radionuclide
14
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A correlation between solar activity,
climate variables (especially
14
temperature) and C activity.
low number of sunspots, higher
activity of C14 and colder climate.
The weak solar field allows more GCR
protons to reach the earth results in
the higher content of C14.
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