Hostname: page-component-78c5997874-lj6df Total loading time: 0 Render date: 2024-11-03T01:29:58.422Z Has data issue: false hasContentIssue false
  • English
  • Français

Miniature Signals and Miniature Counters: Accuracy Assurance Via Microprocessors and Multiparameter Control Techniques

Published online by Cambridge University Press:  18 July 2016

L A Currie ,
R W Gerlach ,
G A Klouda ,
F C Ruegg  and
G B Tompkins
L A Currie
Affiliation:
Center for Analytical Chemistry, National Bureau of Standards Washington, DC 20234
R W Gerlach
Affiliation:
Center for Analytical Chemistry, National Bureau of Standards Washington, DC 20234
G A Klouda
Affiliation:
Center for Analytical Chemistry, National Bureau of Standards Washington, DC 20234
F C Ruegg
Affiliation:
Center for Analytical Chemistry, National Bureau of Standards Washington, DC 20234
G B Tompkins
Affiliation:
Center for Analytical Chemistry, National Bureau of Standards Washington, DC 20234
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

When 14C signals approach background levels, the validity of assumptions concerning Poisson counting statistics and measurement system stability becomes crucial in interpreting the resultant low-level counting observations. This has been demonstrated in our previous work on detection limits for non-Poisson error and it is critical in our current studies of carbonaceous pollutants, where the 14C signal from just 5 mg C is comparable to that of the background for our miniature gas proportional counters. To assure data quality, our multi-detector system is designed for the on-line monitoring of critical parameters that reflect both the (statistical) nature of the non-Poisson errors and the underlying (physical) causes. It sends >60 bits of information/pulse to a microprocessor which automatically generates, for each counting period, two-dimensional spectra and multiparameter correlation and control charts. To evaluate the validity of long-term counting of 1–10 mg C we use robust (statistical) estimators, optimal counting interval subdivision, and time series analysis of the individual pulses. New opportunities for selective sampling and chemical fractionation which come with the small sample measurement capability have led us to give special attention also to higher control levels, involving e g, isotonic heterogeneity and representative standard materials.

Type
V. General Aspects of 14C Technique
Information
Radiocarbon , Volume 25 , Issue 2: 11th International Radiocarbon Conference , 1983 , pp. 553 - 564
Copyright
Copyright © The American Journal of Science 

References

Cooper, JA, Currie, LA, and Klouda, GA, 1981, Assessment of Contemporary carbon combustion source contributions to urban air particulate levels using C-14 measurements: Environmental Sci Technol, v 15, p 1045.Google Scholar
Cooper, JA and Malek, D, eds, 1981, Conference on residential solid fuels, environmental impacts and solutions: Oregon Graduate Center, p 365–385.Google Scholar
Cox, DR and Lewis, PAW, 1966, The statistical analysis of series of events: New York, Wiley & Sons, Chap 6.Google Scholar
Currie, LA, 1973, The limit of precision in nuclear and analytical chemistry: Nuclear Instruments Methods, v 100, p 387–395.Google Scholar
Currie, LA, 1978, Bias Detection, in : New York, John Wiley and Sons, p 151.Google Scholar
Currie, LA, Klouda, GA, Continetti, RE, Kaplan, IR, Wong, WW, Dzubay, TG, and Stevens, RK, 1983, On the origin of carbonaceous particles in American Cities: Results of radiocarbon dating and chemical characterization, in Stuiver, M and Kra, RS, eds, Internatl 14C conf; Radiocarbon, v 25.Google Scholar
Currie, LA, Noakes, J, and Breiter, D, 1979, Measurement of small radiocarbon samples: Power of alternative methods for tracing atmospheric hydrocarbons, in Berger, R and Suess, HE, eds, Radiocarbon dating, Internatl 14C conf, 9th, Proc: Berkeley/Los Angeles, Univ California Press, p 158–175.Google Scholar
Kafadar, K, Rice, J, and Spiegelman, C, 1983, One-sided trimming in small samples with asymmetric contamination: Commun in statistics, theory and methods, v 12, no. 4, p 477–496.Google Scholar
Polach, HA, Soini, E, Kojola, H, Robertson, S, and Kaihola, L, 1982, Radiocarbon dating of milligram-size samples using gas proportional counters: an evaluation of precision and of design parameters, in Australian conf on archaeometry, 1st, Proc: Sydney, Australian Museum.Google Scholar
Sayre, EV, Harbottle, G, Stoenner, RW, Otlet, RL, and Evans, GB, 1981, The use of the small gas proportional counters for the carbon-14 measurement of very small samples, in : IAEA, Vienna, in press.Google Scholar