• Production of Graphite Targets by Deposition from Co/H2 for Precision Accelerator 14C Measurements

      Jull, A. J. T.; Donahue, D. J.; Hatheway, A. L.; Linick, T. W.; Toolin, L. J. (American Journal of Science, 1986-01-01)
      A method has been developed at the Arizona AMS facility for production of graphite directly from CO2 by catalytic reduction of CO/H2 mixtures. The method is a modification of procedures discussed by Vogel et al (1984). Currents of 12C- from these targets vary considerably, but have a median value which is 70% of that achieved from spectroscopic graphite. Precisions of +/- 60 to 100 yr are routinely achieved for 14C ages of 5000-yr-old samples containing one milligram of carbon. The yield of 14C from "blank" targets is 0.6 +/- 0.1% of that from modern material.