• Dating the Turin Shroud—An Assessment

      Gove, H. E. (Department of Geosciences, The University of Arizona, 1990-01-01)
      An assessment is made of the credibility of the radiocarbon dating of the shroud of Turin. The quoted final results produced a calibrated calendar age range of AD 1260–1390 for the linen of the Turin shroud at a 95% confidence level. The measurements were carried out independently in three accelerator mass spectrometry (AMS) laboratories located at the University of Arizona, Tucson, Arizona, USA, Oxford University, Oxford, England, and ETH-Hönggerberg, Zürich, Switzerland with assistance for certification and data analysis provided by the British Museum. The author concludes that, although the procedures followed differed substantially from those recommended at a workshop organized by the Pontifical Academy of Sciences, the results are credible. Although of negligible scientific value, they represent a major public triumph for the AMS method of carbon dating. However, many doubts have been raised, both real and fanciful, concerning the validity of the results and these are discussed. It is suggested that steps should be taken to conserve the shroud and that permission should be given for its examination by experts in medieval art.
    • Discussion: Recovery from Tracer Contamination in AMS Sample Preparation

      Jull, A. J. T.; Donahue, Douglas J.; Toolin, L. J. (Department of Geosciences, The University of Arizona, 1990-01-01)
    • Memory Effects in an AMS System: Catastrophe and Recovery

      Vogel, J. S.; Southon, J. R.; Nelson, D. E. (Department of Geosciences, The University of Arizona, 1990-01-01)
      A sample with a 14C concentration estimated to be greater than 30,000 Modern was inadvertently graphitized and measured in an AMS system. No measurable contamination of the cesium sputter ion source was observed. Simple cleaning procedures removed the contamination from the sample preparation system, with the exception of the reaction vessel in which the sample was graphitized. Sample cross-contamination factors were estimated for all of the preparation and measurement procedures.
    • Superconducting Mini-Cyclotrons as AMS Instruments

      Subotic, K. M.; Milinkovic, L. S.; Zupancic, M. T.; Novkovic, D. N.; Stojanovic, M. S. (Department of Geosciences, The University of Arizona, 1990-01-01)
      We have studied the limitations of conventional mass spectrometry and have examined accelerator based methods which could help circumvent these limitations. In particular, cyclotron-based accelerator mass spectrometric (AMS) techniques are discussed with an emphasis on evaluating performances of superconducting mini-cyclotrons designed for use as AMS instruments. We discussed the design of superconducting mini-cyclotrons dedicated to radioisotope dating research.