Problems Related to Interplanetary Matter (1961) / Chapter Skim
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THE DISTRIBUTION OF RARE GASES IN IRON METEORITES
THE DISTRIBUTION OF RARE GASES IN IRON METEORITES
Pages 31-44
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From page 31... ...
In each sample the concentration of Ar38, Ar3", Ne22, Ne , Ne2 , He4 and He3 was determined in one single extraction process, using a statically operated mass spectrometer. Special techniques were used to prevent contamination of the gas mixture extracted from small meteoritic samples (200 - 400 mg)
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From page 32... ...
Therefore, the curves are not drawn as closed contours. The reference radius is assumed to to be perpendicular to the outer isopleths.
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From page 33... ...
BJ are parameters composed of quantities such as individual production cross sections for the different species; absorption cross sections for primaries and secondaries (also contained in ka and ks) ; the number of secondaries produced per primary interaction, and finally the radiation dosage.
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From page 34... ...
. The close agreement provides evidence that at least in this case the production mechanism proposed by Martin and modified by Ebert and Wanke is adequate to explain the experimental data.
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From page 35... ...
The results agreed closely with those for a spherical body having the same mass and indicated that the assumption of a spherical shape is a reasonable approximation. A knowledge of the parameters also permits one to compute the relative amounts of nuclides produced by primary and secondary particles.
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From page 36... ...
for primary and secondary particles are designated by a • TABLE 2 Relative Contribution of the Secondary-produced Nuclides ffs4/ffp4 's2l/'p2l 0.21 1.0 0.0 0.30 and the secondary production (short dashes) as well as the total concentration (solid line)
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From page 37... ...
produced nuclides in a spherical meteoroid of 2000 kg mass, as computed with the parameters giving best agreement with measurements on Grant. The total amounts are given by the solid lines.
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From page 38... ...
. The crosses indicate seven arbitrarily chosen Grant samples.
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From page 39... ...
indicate some arbitrarily chosen samples of Grant and the symbols (X) represent some measurements of other iron meteorites.
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From page 40... ...
We conclude from this fact, that excluding Washington County* , all the meteorites listed have a chemical composition similar to Grant.
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From page 41... ...
CO 00 OS o ivi o i or•- u"» ox oo a)
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From page 42... ...
Values measured at the center of spherical meteoroids should lie on the dashed curve designated with "center, " whereas surface values are expected to lie on the curve "surface." The curves between two big dots indicate the variation of the ratio He3/Ne21 with the Ar38 concentration in a meteoroid of a particular mass. The small dots represent again the values corresponding to a relative depth of r/R = 0.8; 0.6; 0.4 and 0.2.
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From page 43... ...
[Anders, Arnold and Fireman were concerned about the disagreement between Signer's suggestion of a 12 cm loss of material from the reference axis during flight through the atmosphere and recent metallurgical arguments that this mass loss could not have exceeded 2-6 cm. On the basis of Signer's foregoing comment it has to be remembered that Signer's 40 cm preatmospheric radius for Grant is based on many assumptions as, for example, those of spherical shape and no alteration in the size during the irradiation.
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From page 44... ...
(1960) "The distribution of cosmic-ray produced rare gases in iron meteorites, " J
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