Abstract
Accelerator Mass Spectrometry (AMS) is a technique by which rare radioisotopes such as {sup 14}C can be measured at environmental levels with high efficiency. Instead of detecting radioactivity, which is very weak for long-lived environmental radioisotopes, atoms are counted directly. The sample is placed in an ion source, from which a negative ion beam of the atoms of interest is extracted, mass analysed, and injected into a tandem accelerator. After stripping to positive charge states in the accelerator HV terminal, the ions are further accelerated, analysed with magnetic and electrostatic devices and counted in a detector. An isotopic ratio is derived from the number of radioisotope atoms counted in a given time and the beam current of a stable isotope of the same element, measured after the accelerator. For radiocarbon, {sup 14}C/{sup 13}C ratios are usually measured, and the ratio of an unknown sample is compared to that of a standard. The achievable precision for such ratio measurements is limited primarily by {sup 14}C counting statistics and also by a variety of factors related to accelerator and ion source stability. At the ANTARES AMS facility at Lucas Heights Research Laboratories we are currently able to measure {sup 14}C with 0.5%
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Hotchkis, M A;
Fink, D;
Hua, Q;
Jacobsen, G E;
Lawson, E M;
Smith, A M;
Tuniz, C
[1]
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)
Citation Formats
Hotchkis, M A, Fink, D, Hua, Q, Jacobsen, G E, Lawson, E M, Smith, A M, and Tuniz, C.
Precision and reproducibility in AMS radiocarbon measurements..
Australia: N. p.,
1996.
Web.
Hotchkis, M A, Fink, D, Hua, Q, Jacobsen, G E, Lawson, E M, Smith, A M, & Tuniz, C.
Precision and reproducibility in AMS radiocarbon measurements..
Australia.
Hotchkis, M A, Fink, D, Hua, Q, Jacobsen, G E, Lawson, E M, Smith, A M, and Tuniz, C.
1996.
"Precision and reproducibility in AMS radiocarbon measurements."
Australia.
@misc{etde_618016,
title = {Precision and reproducibility in AMS radiocarbon measurements.}
author = {Hotchkis, M A, Fink, D, Hua, Q, Jacobsen, G E, Lawson, E M, Smith, A M, and Tuniz, C}
abstractNote = {Accelerator Mass Spectrometry (AMS) is a technique by which rare radioisotopes such as {sup 14}C can be measured at environmental levels with high efficiency. Instead of detecting radioactivity, which is very weak for long-lived environmental radioisotopes, atoms are counted directly. The sample is placed in an ion source, from which a negative ion beam of the atoms of interest is extracted, mass analysed, and injected into a tandem accelerator. After stripping to positive charge states in the accelerator HV terminal, the ions are further accelerated, analysed with magnetic and electrostatic devices and counted in a detector. An isotopic ratio is derived from the number of radioisotope atoms counted in a given time and the beam current of a stable isotope of the same element, measured after the accelerator. For radiocarbon, {sup 14}C/{sup 13}C ratios are usually measured, and the ratio of an unknown sample is compared to that of a standard. The achievable precision for such ratio measurements is limited primarily by {sup 14}C counting statistics and also by a variety of factors related to accelerator and ion source stability. At the ANTARES AMS facility at Lucas Heights Research Laboratories we are currently able to measure {sup 14}C with 0.5% precision. In the two years since becoming operational, more than 1000 {sup 14}C samples have been measured. Recent improvements in precision for {sup 14}C have been achieved with the commissioning of a 59 sample ion source. The measurement system, from sample changing to data acquisition, is under common computer control. These developments have allowed a new regime of automated multi-sample processing which has impacted both on the system throughput and the measurement precision. We have developed data evaluation methods at ANTARES which cross-check the self-consistency of the statistical analysis of our data. Rigorous data evaluation is invaluable in assessing the true reproducibility of the measurement system and aids in the identification of physical problems with the system. (authors). 3 refs., 3 figs.}
place = {Australia}
year = {1996}
month = {Dec}
}
title = {Precision and reproducibility in AMS radiocarbon measurements.}
author = {Hotchkis, M A, Fink, D, Hua, Q, Jacobsen, G E, Lawson, E M, Smith, A M, and Tuniz, C}
abstractNote = {Accelerator Mass Spectrometry (AMS) is a technique by which rare radioisotopes such as {sup 14}C can be measured at environmental levels with high efficiency. Instead of detecting radioactivity, which is very weak for long-lived environmental radioisotopes, atoms are counted directly. The sample is placed in an ion source, from which a negative ion beam of the atoms of interest is extracted, mass analysed, and injected into a tandem accelerator. After stripping to positive charge states in the accelerator HV terminal, the ions are further accelerated, analysed with magnetic and electrostatic devices and counted in a detector. An isotopic ratio is derived from the number of radioisotope atoms counted in a given time and the beam current of a stable isotope of the same element, measured after the accelerator. For radiocarbon, {sup 14}C/{sup 13}C ratios are usually measured, and the ratio of an unknown sample is compared to that of a standard. The achievable precision for such ratio measurements is limited primarily by {sup 14}C counting statistics and also by a variety of factors related to accelerator and ion source stability. At the ANTARES AMS facility at Lucas Heights Research Laboratories we are currently able to measure {sup 14}C with 0.5% precision. In the two years since becoming operational, more than 1000 {sup 14}C samples have been measured. Recent improvements in precision for {sup 14}C have been achieved with the commissioning of a 59 sample ion source. The measurement system, from sample changing to data acquisition, is under common computer control. These developments have allowed a new regime of automated multi-sample processing which has impacted both on the system throughput and the measurement precision. We have developed data evaluation methods at ANTARES which cross-check the self-consistency of the statistical analysis of our data. Rigorous data evaluation is invaluable in assessing the true reproducibility of the measurement system and aids in the identification of physical problems with the system. (authors). 3 refs., 3 figs.}
place = {Australia}
year = {1996}
month = {Dec}
}