• Current 14C Measurements with the University of Washington Accelerator Facility for Radioisotope Dating

      Farwell, G. W.; Grootes, P. M.; Leach, D. D.; Schmidt, F. H.; Stuiver, Minze (American Journal of Science, 1983-01-01)
      Our accelerator mass spectrometry (AMS) system shows a one-to-one relationship between sample 14C concentrations determined by AMS and by Beta-counting. Measurements of unknown samples against a standard indicate that 14C concentration measurements to better than 2% can be made. For a 30-second data collection interval in a typical run of 100 intervals, the variability of the beam injected into the accelerator is ca 2%, that of the machine transmission is ca 4%, and counting statistics give 4.7% standard deviation for a sample of 80% of modern carbon.
    • Radiocarbon Dating with the Utrecht Tandem Accelerator

      van der Borg, K.; Hoogenboom, J. A.; Jelmersma, R. A.; Vermeer, Abraham; Hut, Gert (American Journal of Science, 1983-01-01)
    • Radioisotope Dating with the ETHZ-EN-Tandem Accelerator

      Wölfli, Willy; Bonani, Georges; Suter, Martin; Balzer, Richard; Nessi, Marzio; Stoller, Christian; Beer, Jürg; Oeschger, Hans; Andrée, Michael (American Journal of Science, 1983-01-01)
    • Recent 14C Measurements with the Chalk River Tandem Accelerator

      Brown, R. M.; Andrews, H. R.; Ball, G. C.; Burn, Neil; Davies, W. G.; Imahori, Yoshio; Milton, J. C. D.; Workman, Wayne (American Journal of Science, 1983-01-01)
      The Chalk River Tandem Accelerator Mass Spectrometry System has reached a state of reliable measurement of 14C using 2 to 5mg elemental carbon prepared by Mg reduction of CO2. For two comparisons of a near-modern unknown with the NBS oxalic acid standard we obtain a total error of ∼ +/- 4.5%, consisting of a random system error of about +/- 3.5% combined with the statistical counting error. Measurements have been made on 70 samples in 30 days of running time during the past year. Samples included deep rock carbonates, cosmogenic 14C in meteorites, charcoal from earthquake fault zones, collagen of bone artifacts and fossil beetle-fragments.
    • Results of Tests and Measurements from the NSF Regional Accelerator Facility for Radioisotope Dating

      Donahue, D. J.; Zabel, T. H.; Jull, A. J. T.; Damon, P. E.; Purser, K. H. (American Journal of Science, 1983-01-01)
      Tests of performance of the tandem accelerator mass spectrometer at the NSF Regional Facility at the University of Arizona are discussed. Results of measurements on some tree rings and on some archaeologic samples are presented.
    • Tandem Accelerator Measurements of 10Be Deposition Rates

      Nelson, D. E.; Korteling, R. G.; Southon, J. R.; Vogel, J. S.; Nowikow, I.; Ku, T. L.; Kusakabe, Masashi; Reyss, J. L. (American Journal of Science, 1983-01-01)
      A Tandem Van de Graaff accelerator has been modified for use in the direct measurement of natural abundances of 10Be and 14C. A description of the system is given and some 10Be results on oceanographic samples are discussed.
    • Technological Advances in the University of Washington Accelerator Mass Spectrometry System

      Farwell, G. W.; Grootes, P. M.; Leach, D. D.; Schmidt, F. H. (American Journal of Science, 1983-01-01)
      During the past year we have continued to work toward greater stability and flexibility in nearly all elements of our accelerator mass spectrometry (AMS) system, which is based upon an FN tandem Van de Graaff accelerator, and have carried out measurements of 14C/12C and 10Be/9Be isotopic abundance ratios in natural samples. The principal recent developments and improvements in the accelerator system and in our sample preparation techniques for carbon and beryllium are discussed, and the results of a study of 10Be cross-contamination of beryllium samples in the sputter ion source are presented.
    • The Oxford Radiocarbon Accelerator Facility

      Gillespie, Richard; Hedges, R. E. M.; White, N. R. (American Journal of Science, 1983-01-01)