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1.
Re-examination of all known xenon isotopic data for ordinary chondrites reveals that244Pu fission xenon can be resolved in about one-fourth of the meteorites of this class. The amounts of244Pu fission xenon found in these meteorites range from ca. 1–2 up to 6–8·10?12 ccSTP/g. These meteorites started to retain their xenon some 200–500 million years later than did the carbonaceous chondrites Allende, Groznaya, Mokoia, Murchison, Murray, and Renazzo which began to retain their xenon over 4800 million years ago. 相似文献
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Re-calculation of the244Pu ages of lunar rocks 10057 and 12013 indicates that, while the former started to retain its xenon (4,189 ?74 +45 ) million years ago, the latter was formed at a much later time, after the extinct nuclide244Pu had essentially decayed away. 相似文献
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Re-examination of all known xenon isotopic data for the carbonaceous chondrites Renazzo, Mokoia, and Groznaya reveals that these meteorites contain (26±7), (33±1), and (36±4)·10–12 (ccSTP136fXe/g) of244Pu fission xenon, respectively. These meteorites started to retain their xenon more than 4,800 million years ago at about the same time as did the carbonaceous chondrites Allende, Murray, and Murchison. 相似文献
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Re-examination of a vast amount of lead and xenon isotope data that have been accumulated since the Apollo 11 landing on the moon in July 1969 reveals that some of the lunar fines and breccia started to retain their radiogenic lead and fissiogenic xenon isotopes about 5 billion years ago when the ratios of235U and244Pu to238U in the early solar system were approximately 4 and 2 atoms per 10 atoms of238U, respectively. 相似文献
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Re-examination of all known xenon isotopic data for achondrites reveals that244Pu fission xenon can be resolved in about three-fourths of the meteorites of this class. The amounts of244Pu fission xenon found in these meteorites range from ca. 1–2 up to 20–40·10–12 ccSTP/g. These meteorites started to retain their xenon some 200–500 million years later than did the carbonaceous chondrites Allende, Groznaya, Mokoia, Murchison, Murray, and Renazzo, which began to retain their xenon over 4800 million years ago. 相似文献
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Re-examination of all known xenon isotope data for the carbonaceous chondrite Allende reveals that this meteorite contains as much as (22±1)·10–1 2 csSTP per gram of fissogenic136Xe (136fXe) from the extinct nuclide244Pu and it appears to have started to retain its xenon more than 4800 million years ago, when the244Pu to238U ratio in the solar system was 0.113±0.006 (atom/atom). 相似文献
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A number of strange xenon components have been reported in the literature during the past three decades; for example, AVCC (average carbonaceous chondrite), CCF (carbonaceous chondrite fission) xenon, xenon-X, xenon-H, xenon-L, xenon-S, xenon-U, SUCOR (surface correlated xenon), BEOC (Bern Oberflächen-Correliert) xenon, and so on. It is often assumed that they reprsent the isotopic compositions of more or less pure or primordial components of xenon. If one attempts to interpret the existing xenon isotope data for meteorites and lunar samples, assuming that they are pure or primordial, however, one encounters all sorts of problems and no coherent theory concerning the variation of the isotopic composition of xenon in the solar system emerges. We have therefore re-examined over 4,000 sets of existing xenon isotope data for meteorites and lunar samples. The results indicate that these strange xenon components are mixtures of244Pu fission xenon and atmospheric xenon, whose isotopic compositions have been altered by the processes of a) mass-fractionation, b) spallation and c) neutron-capture reactions. 相似文献
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A total of 13 samples of diamond separates studied so far, all contain excess 244Pu fission xenon. On the other hand, none of the SiC separates contains excess 244Pu fission xenon, while 5 out of 10 samples of graphite separates studied so far contain excess 244Pu fission xenon. 相似文献
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The carbonaceous chondrite Allende contains (22±1)·10−12 cm3STP/g of244Pu fission xenon and two kinds of primordial xenon: Type I and Type II. The former represents the isotopic composition of
a primordial xenon, which resided in the vicinity of a supernova shortly before it exploded, while the latter represents that
of the xenon, which resided in the supernova. The isotopic composition of xenon found in the pink inclusion of the Allende
meteorite, corrected for the presence of very large excesses of244Pu fission xenon,129Xe from the decay of129I, and of128Xe from the neutron-capture reactions on127I, resembles that of Type-I primordial xenon. The isotopic composition of xenon found in the diamond inclusions of the Allende
meteorite, on the other hand, represents that of Type-II primordial xenon and it resembles that of a mixture of Type-I primordial
xenon whose isotopic composition is severely altered by a combined effect of (a) mass-fractionation, (b) spallation, (c) stellar-temperature
neutron-capture reactions, and (d) the presence of a large excess of244Pu fission xenon. 相似文献
10.
Xenon found in lunar samples is a binary mixture of244Pu fission xenon and a trapped xenon, whose isotopic composition often shows a striking resemblance to that ofTakaoka's1 primitive xenon. The decay product of129I is conspicuously absent in lunar samples and this may be attributed to the facts that (a) the half-life of129I is much shorter than that of244Pu, and (b) the separation of xenon from plutonium may take place easily, since the former is a gaseous element, while the
latter is a refractory element. The separation of xenon from iodine may not take place easily, however, since the former is
a gaseous element, while the latter is a volatile element. The isotopic compositions of the trapped xenon released from ordinary
chondrites and achondrites resemble that ofTakaoka's primitive xenon, which has been mass-fractionated in such a manner that the heavier isotopes are systematically enriched
relative to the lighter isotopes. 相似文献
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Klaus Brodersen 《Fresenius' Journal of Analytical Chemistry》1959,169(2):139
Ohne Zusammenfassung 相似文献
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Analytical and Bioanalytical Chemistry - 相似文献
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Y. Bourlat J. -C. Millies-Lacroix B. Dunoyer 《Journal of Radioanalytical and Nuclear Chemistry》1994,177(1):107-120
The measurement of re-suspended materials during cleanup operations is currently a concern at many formally-contaminated locations that are being restored. This paper addresses this issue by indicating that the yearly239,240Pu air concentrations increased by a factor of 6 due to re-suspension during cleanup operations at Mururoa. Five sites on the atoll were monitored continuously from 1986 to 1991. The data presented are compared with other data from various parts of the world.The Service Mixte de Sécurité Radiologique is a joint department (Ministry of Defence-Commissariat à l'Energie Atomique) of the Direction des Centres d'Expérimentations Nucléaires. 相似文献
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F. El-Daoushy 《Journal of Radioanalytical and Nuclear Chemistry》2001,250(1):159-164
238, 239-240Pu were measured in German lake sediment coresby counting after radiochemical separation. Their distribution over the bedof the lake was determined. The lake contain 3 basins and for each basin 3sediment cores have been sliced in two subsamples. The results show that theactivity distribution is not the same over the lake and that the sedimentationrate changes in the 3 basins. 相似文献