Progress in AMS measurements at the LLNL spectrometer. [Accelerator Mass Spectroscopy (AMS)] [electronic resource]
The AMS measurement program at LLNL began in earnest in late 1989, and has initially concentrated on ¹⁴C measurements for biomedical and geoscience applications. We have now begun measurements on ¹°Be and ³⁶Cl, are presently testing the spectrometer performance for ²⁶Al and ³H, and will begin tests...
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Online Access |
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| Format: | Government Document Electronic eBook |
| Language: | English |
| Published: |
Washington, D.C. : Oak Ridge, Tenn. :
United States. Dept. of Defense ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy,
1991.
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| Summary: | The AMS measurement program at LLNL began in earnest in late 1989, and has initially concentrated on ¹⁴C measurements for biomedical and geoscience applications. We have now begun measurements on ¹°Be and ³⁶Cl, are presently testing the spectrometer performance for ²⁶Al and ³H, and will begin tests on ⁷Be, ⁴¹Ca and ¹²⁹I within the next few months. Our laboratory has a strong biomedical AMS program of ¹⁴C tracer measurements involving large numbers of samples (sometimes hundreds in a single experiment) at ¹⁴C concentrations which are typically .5--5 times Modern, but are occasionally highly enriched. The sample preparation techniques required for high throughput and low cross-contamination for this work are discussed elsewhere. Similar demands are placed on the AMS measurement system, and in particular on the ion source. Modifications to our GIC 846 ion source, described below, allow us to run biomedical and geoscience or archaeological samples in the same source wheel with no adverse effects. The source has a capacity for 60 samples (about 45 unknown) in a single wheel and provides currents of 30--60μA of C⁻ from hydrogen-reduced graphite. These currents and sample capacity provide high throughput for both biomedical and other measurements: the AMS system can be started up, tuned, and a wheel of carbon samples measured to 1--1.5% in under a day; and 2 biomedical wheels can be measured per day without difficulty. We report on the present status of the Lawrence Livermore AMS spectrometer, including sample throughput and progress towards routine 1% measurement capability for ¹⁴C, first results on other isotopes, and experience with a multi-sample high intensity ion source. 5 refs. |
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| Item Description: | Published through the Information Bridge: DOE Scientific and Technical Information. 06/01/1991. "ucrl-jc-107498" " conf-9105225--1" "DE91015112" 14. international radiocarbon conference, Tucson, AZ (United States), 20-24 May 1991. Davis, J.C.; Roberts, M.L.; Vogel, J.S.; Finkel, R.; Caffee, M.; Southon, J.R.; Proctor, I.D.; Trumbore, S.E.; Heikkinen, D.W.; Hornady, R.S.; Berno, A.J. |
| Physical Description: | Pages: (11 p) : digital, PDF file. |