Radiocarbon from Pile Graphite; Chemical Methods for its Concentration

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Abstract. Samples of pile graphite, irradiated in a test-hole at Hanford for 15 months, have been assayed for radioactive C14, yielding 0.38 ± 0.04 microcuries per gram. At this level of activity, the pile graphite contains very valuable amounts of C14. The relation between the above assay and the probable average assay of pile graphite is discussed, and it is concluded that the latter is almost certainly above 0.3 uc/ gram. Controlled oxidation of this graphite, either with oxygen at ~ 750°C, or with chromic acid "cleaning solution" at room temperature, yields early fractions which are highly enriched in C14. … continued below

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26 pages : illustrations

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Arnold, James R. & Libby, Willard F. October 10, 1946.

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Abstract. Samples of pile graphite, irradiated in a test-hole at Hanford for 15 months, have been assayed for radioactive C14, yielding 0.38 ± 0.04 microcuries per gram. At this level of activity, the pile graphite contains very valuable amounts of C14. The relation between the above assay and the probable average assay of pile graphite is discussed, and it is concluded that the latter is almost certainly above 0.3 uc/ gram. Controlled oxidation of this graphite, either with oxygen at ~ 750°C, or with chromic acid "cleaning solution" at room temperature, yields early fractions which are highly enriched in C14. Concentrations of 5-fold with oxygen, and 50-fold with CRO{sub3}, have been observed. The relation between the observed enrichment and the Wigner effect is discussed, and a mechanism accounting for the observations put forward. According to this, about 25% of the stable carbon atoms in the lattice have been displaced by Wigner effect, a large fraction of which have healed the migrating to crystal edges. All the C14 atoms have been displaced, and the same fraction of these migrate to the edges. The enrichment then results from surface oxidation, in the oxygen case. Predictions are made on the basis of this hypothesis. A technique of counting radioactive CO2 in the gas phase is described

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26 pages : illustrations

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  • SuDoc Number: Y 3.At 7:22/CC-3643
  • Report No.: CC-3643
  • Accession or Local Control No: metadc1256422
  • Archival Resource Key: ark:/67531/metadc1256422

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  • October 10, 1946

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  • Aug. 10, 2021, 7:39 a.m.

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  • Jan. 27, 2022, 11:02 a.m.

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Arnold, James R. & Libby, Willard F. Radiocarbon from Pile Graphite; Chemical Methods for its Concentration, report, October 10, 1946; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc1256422/: accessed July 13, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.

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