Trials and tribulations in the first three years in operation of the SSAMS for biomedical 14C-AMS at LLNL

T. J. Ognibene, K. W. Haack, G. Bench, Ken W Turteltaub

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

We report on the first several years of operation of our recently installed 250 kV SSAMS at LLNL, purchased to replace our 1-MV AMS system for the measurement of 14C from labeled biochemical samples. We have modified the ion source region to improve ion output. Additionally, the SSAMS required significant software modifications to the data acquisition system in order to accurately measure 14C at the high-count rates typically encountered with labeled biochemical samples. We found that the data can be corrected assuming a nonparalyzable dead time response with a single event dead time of 6 µs. Since operation began, we have measured over 13,000 graphitic unknowns and over 1900 standards with an overall precision of 1.0%. We have optimized our system for the analysis of CO2 gas samples. We compared aliquots of identical samples measured as solid graphite and as liquid drops. Excellent agreement was found between the two, although the average precision of the graphite targets was an order of magnitude better than the liquid drop analysis due to the much larger number of 14C atoms available for measurement.

Original languageEnglish (US)
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
DOIs
StateAccepted/In press - Jan 1 2018
Externally publishedYes

Fingerprint

Alpha Magnetic Spectrometer
Graphite
Liquids
Ion sources
Data acquisition
graphite
Atoms
time response
Ions
Gases
ion sources
data acquisition
computer programs
output
gases
atoms
ions

Keywords

  • Accelerator mass spectrometry
  • Biomedical AMS
  • Gas ion source
  • SSAMS

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation

Cite this

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title = "Trials and tribulations in the first three years in operation of the SSAMS for biomedical 14C-AMS at LLNL",
abstract = "We report on the first several years of operation of our recently installed 250 kV SSAMS at LLNL, purchased to replace our 1-MV AMS system for the measurement of 14C from labeled biochemical samples. We have modified the ion source region to improve ion output. Additionally, the SSAMS required significant software modifications to the data acquisition system in order to accurately measure 14C at the high-count rates typically encountered with labeled biochemical samples. We found that the data can be corrected assuming a nonparalyzable dead time response with a single event dead time of 6 µs. Since operation began, we have measured over 13,000 graphitic unknowns and over 1900 standards with an overall precision of 1.0{\%}. We have optimized our system for the analysis of CO2 gas samples. We compared aliquots of identical samples measured as solid graphite and as liquid drops. Excellent agreement was found between the two, although the average precision of the graphite targets was an order of magnitude better than the liquid drop analysis due to the much larger number of 14C atoms available for measurement.",
keywords = "Accelerator mass spectrometry, Biomedical AMS, Gas ion source, SSAMS",
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AU - Bench, G.

AU - Turteltaub, Ken W

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N2 - We report on the first several years of operation of our recently installed 250 kV SSAMS at LLNL, purchased to replace our 1-MV AMS system for the measurement of 14C from labeled biochemical samples. We have modified the ion source region to improve ion output. Additionally, the SSAMS required significant software modifications to the data acquisition system in order to accurately measure 14C at the high-count rates typically encountered with labeled biochemical samples. We found that the data can be corrected assuming a nonparalyzable dead time response with a single event dead time of 6 µs. Since operation began, we have measured over 13,000 graphitic unknowns and over 1900 standards with an overall precision of 1.0%. We have optimized our system for the analysis of CO2 gas samples. We compared aliquots of identical samples measured as solid graphite and as liquid drops. Excellent agreement was found between the two, although the average precision of the graphite targets was an order of magnitude better than the liquid drop analysis due to the much larger number of 14C atoms available for measurement.

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