Ion-optics calculations of the LLNL AMS system for biochemical 14C measurements

Ognibene, Ted; Brown, Thomas A.; Knezovich, John P.; Roberts, M.L.; Southon, J.R.; Vogel, John S.

doi:10.1016/s0168-583x(00)00151-8

Cited by 13 publications

(11 citation statements)

References 5 publications

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“…The material was known to be 14 C-dead from 4 + AMS measurements at 6.5 MV. Count rates equivalent to 30 pMC (T Ognibene, personal communication) were observed on a small NEC AMS system at LLNL (Ognibene et al 2000), similar to ours but with poorer vacuum in the HE magnet. Scaling the results for our system to samples of normal 13 C content, we can expect backgrounds in the 0.05-0.1 pMC range.…”

Section: Scatteringsupporting

confidence: 79%

The Keck Carbon Cycle AMS Laboratory, University of California, Irvine: Initial Operation and a Background Surprise

et al. 2004

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ABSTRACT.A new radiocarbon accelerator mass spectrometry (AMS) laboratory for carbon cycle studies has been established at the University of California, Irvine. The 0.5MV AMS system was installed in mid-2002 and has operated routinely since October of that year. This paper briefly describes the spectrometer and summarizes lessons learned during the first year of operation. In the process of setting up the system, we identified and largely suppressed a previously unreported 14 C AMS background: charge exchange tails from 14 N beams derived from nitrogen-containing molecular ions produced near the entrance of the accelerator.

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Section: Scatteringsupporting

confidence: 79%

The Keck Carbon Cycle AMS Laboratory, University of California, Irvine: Initial Operation and a Background Surprise

et al. 2004

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“…This spectrometer was carefully designed for maximal loss-free transmission [40] of ions produced by the uniquely intense LLNL ion source [41] from samples reduced to carbon with a high-throughput process [29]. However, most analytical properties described here arise from the fundamental isotope ratio nature of an AMS measurement on a homogeneous sample and will be applicable to most well-designed and operated AMS spectrometers.…”

Section: Resultsmentioning

confidence: 99%

Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development

2010

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The validation parameters for pharmaceutical analyses were examined for the accelerator mass spectrometry measurement of 14C/C ratio, independent of chemical separation procedures. The isotope ratio measurement was specific (owing to the 14C label), stable across samples storage conditions for at least 1 year, linear over four orders of magnitude with an analytical range from 0.1 Modern to at least 2000 Modern (instrument specific). Furthermore, accuracy was excellent (between 1 and 3%), while precision expressed as coefficient of variation was between 1 and 6% determined primarily by radiocarbon content and the time spent analyzing a sample. Sensitivity, expressed as LOD and LLOQ was 1 and 10 attomoles of 14C, respectively (which can be expressed as compound equivalents) and for a typical small molecule labeled at 10% incorporated with 14C corresponds to 30 fg equivalents. Accelerator mass spectrometry provides a sensitive, accurate and precise method of measuring drug compounds in biological matrices.

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“…It contains a 1MV NEC Pelletron accelerator, but was assembled from NEC and LLNL components rather than purchased as a unit. The ion optics of the spectrometer (Ognibene et al 2000) were designed to accept the output of the LLNL high-intensity ion source (Southon and Roberts 2000), which is routinely operated at ion currents of 100-250 µA 12 C -, with 14 C count rates of 200-400 cps for Modern samples. These high count rates make possible detailed testing of equivalence between counting statistics and measurement precisions within reasonable time periods.…”

Section: Uncertainties In Amsmentioning

confidence: 99%

Counting Statistics and Ion Interval Density in AMS

et al. 2004

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Confidence in the precisions of accelerator mass spectrometry (AMS) and decay measurements must be comparable for the application of the radiocarbon calibration to age determinations using both technologies. We confirmed the random nature of the temporal distribution of 14C ions in an AMS spectrometer for a number of sample counting rates and properties of the sputtering process. The temporal distribution of ion counts was also measured to confirm the applicability of traditional counting statistics.

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Ion-optics calculations of the LLNL AMS system for biochemical 14C measurements

Abstract: A dedicated AMS system for biochemical 14 C measurements is being built at Center for Accelerator Mass Spectrometry. The system is centered around a National

Cited by 13 publications

References 5 publications

The Keck Carbon Cycle AMS Laboratory, University of California, Irvine: Initial Operation and a Background Surprise

The Keck Carbon Cycle AMS Laboratory, University of California, Irvine: Initial Operation and a Background Surprise

Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development

Counting Statistics and Ion Interval Density in AMS

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