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| Titel |
The effects of irradiation on the magnetic properties of rock and synthetic samples |
| VerfasserIn |
N. S. Bezaeva, P. Rochette, J. Gattacceca, J. Duprat, G. Rizza, P. Vernazza, V. I. Trukhin |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250029094
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| Zusammenfassung |
| Irradiations in space, by solar wind (SW), solar cosmic rays (SCR) (i.e., solar-flare-associated
particles or solar energetic particles) and galactic cosmic rays (GCR) – the main source of
space weathering of the solid Solar System bodies – may result in changes in magnetic
properties of extraterrestrial materials, thus complicating the interpretation of the magnetism
of meteorites, micrometeorites and lunar samples. The objective of this work was to check the
effect of irradiation on the magnetic remanence and intrinsic magnetic properties of the main
magnetic carriers of extraterrestrial materials: iron and FeNi alloys, Ti-rich and Ti-free
magnetite, and pyrrhotite. We performed irradiation experiments on rock and synthetic
samples using protons, the most abundant elements in space radiations, with energies
(E1=400 keV and E2=850 keV) close to these of SCR protons. We also performed
irradiation experiments using argon ions (E=400 keV) and lead ions (E=1 GeV or ~5
MeV per nucleon) to check the degree of irradiation-induced damage compared to
protons.
Corresponding rock magnetic analyses were carried out before and after irradiation
experiments. Irradiation by protons produced a significant increase in coercivity of
remanence (Bcr) in a taenite-bearing meteorite as well as in synthetic iron and magnetite.
Similar effect of magnetic hardening was found in FeNi-bearing Bereba and Tatahouine HED
meteorites, irradiated by argon ions. Considering the maximum penetration depth of SCR
protons with ~MeV energies (from μm to mm), this suggests that space radiations could
result in magnetic hardening of nickel-iron bearing planetary surface materials,
micrometeorites and meteorites containing regolith breccias. In the first millions years after
gravitational collapse of the proto-star (early solar system), when SCR flux was far more
abundant, it could result in magnetic hardening of primary chondritic material. Irradiation by
heavy ions did not produce any changes in Bcr but resulted in changes of saturation
isothermal remanent magnetization, directly related to the capacity of rocks to acquire
remanent magnetization. |
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