• Determination of Radon by Liquid Scintillation alpha/Beta Particle Spectrometry: Towards the Resolution of a 14C Dating Problem

      Polach, Henry; Kaihola, Lauri (American Journal of Science, 1988-01-01)
      Traces of uranium and radium within the 14C sample generate radon (Rn) which gets occluded during the benzene synthesis, thus generating false (extra) counts within the 14C counting window. This, if undetected, gives rise to erroneous 14C age determinations. The application of simultaneous alpha and Beta liquid scintillation spectrometry will enable a mathematical evaluation of the 14C signal unaffected by alpha and Beta particle emissions from radon decay daughters.
    • Gif Natural Radiocarbon Measurements XI

      Delibrias, Georgette; Guillier, Marie-Therese (American Journal of Science, 1988-01-01)
    • Growth Rates of Natural Amazonian Forest Trees Based on Radiocarbon Measurements

      Mozeto, A. A.; Fritz, Peter; Moreira, M. Z.; Vetter, E.; Aravena, Ramon; Salati, Eneas; Drimmie, R. J. (American Journal of Science, 1988-01-01)
      Evergreen trees in the tropical rain forest of the Amazonas Basin can produce growth rings which are not necessarily related to annual events. Therefore, estimation of growth rate cannot be done by dendrochronology. This report presents a technique for determining the growth rate of these trees based on radiocarbon measurements of two segments of equal radial distance from the outer part of the tree trunk. The measured 14C activity is compared to local 14C fallout and growth rates are derived from models taking into account bomb 14C effects. Eleven trees from various parts of the Amazon Basin were analyzed. The average growth rates range from ca 5 to > 40 yr per centimeter corresponding to extrapolated ages from ca 60 to > 400 yr.
    • Hiroshima University Radiocarbon Dates I: West and South Coasts of Sri Lanka

      Katupotha, Jinadasa (American Journal of Science, 1988-01-01)
    • Letter to the Editor

      Letolle, René (American Journal of Science, 1988-01-01)
    • Preliminary Statement on an Error in British Museum Radiocarbon Dates

      Tite, M. S.; Bowman, S. G. E.; Ambers, J. C.; Matthews, K. J. (American Journal of Science, 1988-01-01)
    • Radiocarbon, Volume 30, Number 1 (1988)

      American Journal of Science, 1988-01-01
    • The Relations Between Carbon Isotope Composition and Apparent Age of Freshwater Tufaceous Sediments

      Pazdur, Anna (American Journal of Science, 1988-01-01)
      This paper presents a synthetic approach to 14C dating of calcareous tufa, based on statistical analysis of correlations betwen lithologic type of tufaceous sediment, carbon isotope composition, and apparent age. Experimental data on several profiles from southern Poland and the United Kingdom reveal either constant or systematically changing values of apparent age. Constant value of apparent age in a profile can be attributed to calcareous muds precipitated from stagnant or low-energy water, and to tufas precipitated from turbulent water (oncoids, stromatolites, moss travertines) which are characterized by lack of significant correlation between delta-13C and 14C age of tufa carbonate. It was found that the relation between the apparent age of tufaceous sediment and delta-13C value of tufa carbonate depends on lithologic type of tufa. Phenomenological equations describing the dependence of apparent age upon delta-13C are given, and applied to estimate true ages of tufas from Gliczarow (southern Poland) and Folkestone (United Kingdom).
    • The Second International Symposium on Archaeology and 14C

      Kra, Renee (American Journal of Science, 1988-01-01)
    • US Geological Survey, Denver, Colorado Radiocarbon Dates V

      Yang, I. C. (American Journal of Science, 1988-01-01)