• Accelerator Mass Spectrometry: From Nuclear Physics to Dating

      Kutschera, Walter (American Journal of Science, 1983-01-01)
    • Detection of the 36Cl Radioisotope at the Rehovot 14UD Pelletron Accelerator

      Paul, Michael; Meirav, Oded; Henning, Walter; Kutschera, Walter; Kaim, Robert; Goldberg, Mark B.; Gerber, Jean; Hering, William; Kaufman, Aaron; Magaritz, Mordeckai (American Journal of Science, 1983-01-01)
      A program of accelerator mass spectrometry has been started at the Rehovot 14UD Pelletron Accelerator Laboratory. Part of the initial emphasis has been directed to the detection of the 36Cl radioisotope. We report here on the present status of our work and describe our experimental system. Preliminary results are presented, showing that 36Cl/Cl concentrations ranging down to 1 x 10−14 could be measured with our system.
    • Production of C- Directly from CO2 Using the ANIS Sputter Source

      Heinemeier, Jan; Andersen, Hans Henrik (American Journal of Science, 1983-01-01)
      Micro-ampere beams of C- have been produced with the Aarhus negative-ion source, operated on CO2 gas. The efficiency of the source and memory effects have been measured, using 13C-enriched CO2, in order to evaluate the applicability of the source to 14C dating by accelerator mass spectroscopy.
    • Sample Chemistry for the Oxford High Energy Mass Spectrometer

      Gillespie, Richard; Hedges, Robert E. M. (American Journal of Science, 1983-01-01)
      Chemical pretreatment procedures for the decontamination, extraction, and isolation of organic materials for 14C dating using the Oxford accelerator system are described. Specific details are given for the isolation and chromatographic purification of amino acids from bone and tooth collagen, of lipids from sediments, and of cellulose and glucose from wood, paper, and textiles. A description is also given of the apparatus used for the routine preparation of 1 to 5mg graphite samples on tantalum wire, for use in the accelerator ion source. The high energy mass spectrometer (HEMS) approach to 14C dating allows the use of very small samples in the low milligram range. Sample pretreatment and decontamination procedures can be both more vigorous and more selective than those used by conventional dating laboratories. Specific chemical compounds can be isolated from archaeologic or geologic samples; such compounds may be characteristic of particular source materials and, hence, provide more detailed information than is generally possible using bulk organic samples. The Oxford Radiocarbon Unit has concentrated on three sample types that represent the kind of material we expect to work on initially: bone, lake sediment, and wood.
    • Survey of Simple Carbon Compounds for Use in a Negative Ion Sputter Source

      Vogel, J. S.; Nowikow, I. G.; Southon, J. R.; Nelson, D. E. (American Journal of Science, 1983-01-01)
      We present a survey of carbon beam yields from 20 simple carbon compounds using a caesium sputter source and the McMaster University tandem accelerator. The carbon yield was measured as a 35MeV 12C4+ beam. We found that the beam intensities could be related to a grouping of the carbides according to the chemical bonding of the compounds. The usefulness of the compounds for accelerator 14C dating was further related to their preparation chemistries. Strontium carbide was the equal of graphite in negative carbon ion beam production and aluminum carbide was found to be a good candidate for further tests because of its good sputter yield and preparation chemistry. Charcoal was also tested with varying amounts of silver added as a heat conduction aid.