Original Date: 01/27/1997
Revision Date: 01/18/2007
Best Practice : Accelerator Mass Spectrometry
At Lawrence Livermore National Laboratory (LLNL), the Center for Accelerator Mass Spectrometry (CAMS) develops and operates accelerator-based isotopic abundance measurements using accelerator mass spectrometry (AMS) and spatially-defined elemental distributions using an ion microprobe, for a wide range of applications. CAMS has applied these techniques in biodosimetry; atmospheric and geoscience mechanisms; paleoclimatology; non-proliferation; and materials science. External collaborators and fee-for-service users conduct research in archaeology; oceanography; clinical and nutritional sciences; genotoxicity screening; intelligence; and art history.
AMS detects long-lived radioisotopes to sensitivities of 1:1015 (or one part in a thousand-million-million) in only a few minutes. CAMS has established AMS analysis for the cosmogenic isotopes 3H, 7Be, 14C, 26Al, 36Cl, 41Ca, 59, 63 Ni, and 129I. New capabilities are being developed to measure isotopes of iron and selenium for use in protein labeling and tracing. Continuing development will extend this isotope capability over much of the Periodic Table of elements. Figure 2-9 shows a simple schematic of the AMS system.
Another technique CAMS has developed uses a MeV ion microprobe to characterize elemental distributions at micron spatial resolution and five parts-per-million sensitivity. This technique has applications in many biological systems; for example, a simultaneous measurement of multiple elemental profiles within individual cells and cellular organelles with approximately 10-18 mole sensitivity for trace metals and specific proteins has been demonstrated.
These unique techniques may be used to address important problems in management of health and environmental risks and in fundamental biochemistry. An example is in the established field of tagged radiocarbon tracing. With the AMS technology, CAMS is able to provide results that are 103 to 106 times more sensitive than conventional counting techniques. In many applications, extremely small amounts of the tagged material, that are well below regulatory control, can be traced with accuracy.
Figure 2-9. Schematic of the CAMSí AMS System
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