Radiocarbon Dating at the University of Washington III

This date list consists of those measurements made since 1962. The counter is one described previously (Fairhall and Schell, 1963). The results are computed using NBS oxalic acid as the standard and 5568 for the half-life of C14. Standard deviations are computed for each measurement, including the statistical error in the sample count and uncertainties in background and standard. In general, each sample is counted at least twice. The quoted error on the date is the standard deviation. A 2σ criterion is used to establish a lower limit to the age of very old samples with no detectable trace of C14. No correction for isotope fractionation has been made in any of the measurements.

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Bratislava Radiocarbon Measurements II

Radiocarbon ◽

10.1017/s0033822200003714 ◽

1977 ◽

Vol 19 (3) ◽

pp. 389-391

Author(s):

S Usačev ◽

J Chrapan ◽

J Oravec ◽

B Sitár

Keyword(s):

Oxalic Acid ◽

Proportional Counter ◽

Half Life ◽

Nuclear Physics ◽

Radiocarbon Dating ◽

Initial Conditions ◽

Sample Pretreatment ◽

Active Volume ◽

Statistical Errors ◽

Sample Count

Radiocarbon dating facilities were built at the Department of Nuclear Physics, Comenius University in 1967 (Usačev et al, 1973). Initially, sample pretreatment and combustion systems for a proportional counter filled with CO2 were installed (Chrapan, 1966). One group adopted methods based on the use of methane (Usačev et al, 1973), a second group continued radiocarbon dating using an Oeschger-type proportional counter filled with CO2 (Chrapan, 1968). Later a modified Oeschger-type proportional counter with 1L active volume and with a background of approximately 8.10–2 bq was built (Schmidt and Chrapan, 1970). The pressure used in this counter is 105 Pa. 0.95 NBS oxalic acid is used as a standard of the present biosphere and the year 1950 refers to the zero year. Calculated radiocarbon ages are based on a 5568 ± 30 year half-life as recommended by the 8th International Radiocarbon Dating Conference. Statistical errors are calculated as a combination of the 3σ standard deviations of the sample count and the background. Samples were treated by HCl, NaOH or other chemicals according to their initial conditions.

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UCLA Radiocarbon Dates II

Radiocarbon ◽

10.1017/s0033822200036742 ◽

1963 ◽

Vol 5 ◽

pp. 1-22 ◽

Cited By ~ 37

Author(s):

G. J. Fergusson ◽

W. F. Libby

Keyword(s):

Oxalic Acid ◽

Half Life ◽

Radiocarbon Dating ◽

Radiocarbon Dates ◽

Made In ◽

Modern Standard

The measurements reported in this list have been made in the Isotope Laboratory at the Institute of Geophysics, UCLA during 1962. Dates have been calculated on the C14 half life of 5568 years and using 95% NBS oxalic acid as modern standard, in agreement with the decision of the Fifth Radiocarbon Dating Conference (Godwin, 1962).

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Birmingham University Radiocarbon Dates VI

Radiocarbon ◽

10.1017/s0033822200058574 ◽

1973 ◽

Vol 15 (1) ◽

pp. 1-12 ◽

Cited By ~ 11

Author(s):

F. W. Shotton ◽

R. E. G. Williams

Keyword(s):

Statistical Analysis ◽

Standard Deviation ◽

Oxalic Acid ◽

Sample Size ◽

Mass Spectrometer ◽

Half Life ◽

Radiocarbon Dating ◽

Radiocarbon Dates

The following list comprises results obtained during 1971 from both the 1 L and 6 L proportional gas counters at pressures of 1 to 3 atm of methane. Age calculations are based on 95% activity of NBS oxalic acid standard and computed from the Libby half-life of 5570 ± 30 yr. Background samples are synthesized from Welsh anthracite. Errors quoted refer only to the standard deviation (1σ) calculated from a statistical analysis of sample, background, and standard count rates. Recently a Micromass 6 mass spectrometer was installed in the Radiocarbon Dating Laboratory which will enable C13 measurements on future samples. Pretreatment is continued as described previously (R., 1969, v. 11, p. 263) but in cases where sample size was insufficient for full pretreatment, details are described.

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Isotopes' Radiocarbon Measurements IX

Radiocarbon ◽

10.1017/s003382220000103x ◽

1972 ◽

Vol 14 (1) ◽

pp. 114-139 ◽

Cited By ~ 13

Author(s):

James Buckley ◽

Eric H. Willis

Keyword(s):

Oxalic Acid ◽

Half Life ◽

Radiocarbon Dating ◽

Sample Pretreatment ◽

Actual Sample ◽

Sample Data ◽

Counting Time ◽

Standard Deviations ◽

Age Determinations ◽

Made In

The measurements presented in this date list were made in the Radiocarbon Dating Laboratory at Teledyne Isotopes during 1969–70. Samples were analyzed by techniques described in R., 1968, v. 10, p. 246. Methods and references to sample pretreatment are provided in R., 1970, v. 12, p. 87. Errors associated with the age determinations are calculated by combining standard deviations from oxalic acid standard, background, and actual sample data. Samples which approach modern or background are reported with at least 2σ limits. Counting time for calculation of errors of background and standard is the same as that used for the sample. The error associated with the De Vries effect and the uncertainty of the half-life are not included.

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National Physical Laboratory Radiocarbon Measurements IV

Radiocarbon ◽

10.1017/s0033822200000205 ◽

1966 ◽

Vol 8 ◽

pp. 340-347 ◽

Cited By ~ 5

Author(s):

W. J. Callow ◽

M. J. Baker ◽

Geraldine I. Hassall

Keyword(s):

Standard Deviation ◽

Standard Error ◽

Half Life ◽

Count Rate ◽

National Physical Laboratory ◽

Background Count ◽

Best Value ◽

Sample Count ◽

The Difference ◽

Absolute Age

The following list comprises measurements made since those reported in NPL III and is complete to the end of November 1965.Ages are relative to A.D. 1950 and are calculated using a half-life of 5568 yr. The measurements, corrected for fractionation (quoted δC13 values are relative to the P.D.B. standard), are referred to 0.950 times the activity of the NBS oxalic acid as contemporary reference standard. The quoted uncertainty is one standard deviation derived from a proper combination of the parameter variances as described in detail in NPL III. These variances are those of the standard and background measurements over a rolling twenty week period, of the sample δC14 and δC13 measurements and of the de Vries effect (assumed to add an additional uncertainty equivalent to a standard deviation of 80 yr). Any uncertainty in the half-life has been excluded so that relative C14 ages may be correctly compared. Absolute age assessments, however, should be made using the accepted best value for the half-life and the appropriate uncertainty then included. If the net sample count rate is less than 4 times the standard error of the difference between the sample and background count rates, a lower limit to the age is reported corresponding to a net sample count rate of 4 times the standard error of this difference.

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Tartu Radiocarbon Dates XIII

Radiocarbon ◽

10.1017/s0033822200014399 ◽

1994 ◽

Vol 36 (1) ◽

pp. 153-158

Author(s):

Arvi Liiva ◽

Ilze Loze

Keyword(s):

Standard Deviation ◽

Oxalic Acid ◽

Liquid Scintillation Counting ◽

Half Life ◽

Liquid Scintillation ◽

Standard Sample ◽

Scintillation Counting ◽

Radiocarbon Dates ◽

Academy Of Sciences ◽

Modern Standard

This date list reports dates of archaeological samples of Mesolithic and Neolithic sites of Estonia, Latvia and Lithuania. We use liquid scintillation counting at the Geochemical and Statistical Laboratory of the Institute of Zoology and Botany, Estonian Academy of Sciences. Our modern standard is benzene enriched in 14C and its activity is checked with an NBS oxalic acid standard sample. Dates are given in conventional 14C years, based on the Libby half-life of 5570 ± 30 yr. AD 1950 is the reference year. Errors are based on one standard deviation calculated from count rates.

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Lyon Natural Radiocarbon Measurements VIII

Radiocarbon ◽

10.1017/s0033822200004562 ◽

1979 ◽

Vol 21 (3) ◽

pp. 405-452 ◽

Cited By ~ 10

Author(s):

J Evin ◽

G Marien ◽

C Pachiaudi

Keyword(s):

Standard Deviation ◽

Chemical Treatment ◽

Calculation Method ◽

Half Life ◽

Liquid Scintillation ◽

Small Samples ◽

Sample Versus ◽

Made In

This list includes most of the measurements made in 1977 and 1978 using the two Packard liquid scintillation spectrometers described in Lyon VII (R, 1978, v 20, p 19). The backgrounds of both spectrometers decreased by about 30% with new photomultipliers, giving 1.9 ± 0.1cpm and 2.4 ± 0.2 cpm, respectively, for 3ml C6H6(depending on counting vessels). Proportional detectors are only used for very small samples. Counting procedures are described in the text. Dilution ratios indicate the amount of sample versus the total quantity of C6H6or CO2introduced in the detectors. No change was made either in chemical treatment or in the calculation method (half-life: 5570 ± 0, one standard deviation, standard13C correction only for bones).

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University of Michigan Radiocarbon Dates XI

Radiocarbon ◽

10.1017/s0033822200000163 ◽

1966 ◽

Vol 8 ◽

pp. 256-285 ◽

Cited By ~ 13

Author(s):

H. R. Crane ◽

James B. Griffin

Keyword(s):

Standard Deviation ◽

Half Life ◽

Radiocarbon Dating ◽

Geiger Counter ◽

University Of Michigan ◽

Radiocarbon Dates ◽

Statistical Errors ◽

Sources Of Error ◽

The Many ◽

Many Sources

The following is a list of dates obtained since the time of the compilation of List X in December 1964. The method is essentially the same as that used for the work described in the previous list. Two CO2-CS2Geiger counter systems are used. The equipment and counting techniques have been described elsewhere (Crane, 1961). The dates and estimates of error in this list follow the practice recommended by the International Radiocarbon Dating Conferences of 1962 and 1965, in that (a) dates are computed on the basis of the Libby half-life, 5570 yr, (b) A.D. 1950 is used as the zero of the age scale, and (c) the errors quoted are the standard deviations obtained from the numbers of counts only. In previous Michigan date lists up to and including VII we have quoted errors at least twice as great as the statistical errors of counting, in order to take account of other errors in the over-all process. If the reader wishes to obtain a standard deviation figure which will allow ample room for the many sources of error in the dating process, we suggest he double the figures that are given in this list.

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University of Michigan Radiocarbon Dates VIII

Radiocarbon ◽

10.1017/s0033822200036870 ◽

1963 ◽

Vol 5 ◽

pp. 228-253 ◽

Cited By ~ 22

Author(s):

H. R. Crane ◽

James B. Griffin

Keyword(s):

Standard Deviation ◽

Half Life ◽

Radiocarbon Dating ◽

Geiger Counter ◽

University Of Michigan ◽

Radiocarbon Dates ◽

Statistical Errors ◽

Counting Technique ◽

Life Scale ◽

The Many

The following is a list of dates obtained since the time of the compilation of List VII in December 1961. The method is essentially the same as that used for the work described in the previous list. Two CO2-CS2 Geiger counter systems are used. The equipment and counting technique have been described elsewhere (Crane, 1961a, 1961b). The dates and the estimates of error in this list follow the practice recommended by the International Radiocarbon Dating Conference of 1962, in that (a) dates are computed on the basis of a half life of 5568 years, (b) a.d. 1950 is used as the zero of the age scale and (c) the errors quoted are the standard deviations obtained from the numbers of counts only. In all previous Michigan date lists we have quoted errors at least twice as great as the statistical errors of counting, in order to take account of other errors in the over-all process. If the reader wishes to obtain a standard deviation figure which will allow ample room for the many other sources of error in the dating process, we suggest he double the figures that are given in this list. The procedures for converting the dates to the more recent half life scale and to a scale having its zero at any time other than 1950 need not be given here as they have been covered in this journal and elsewhere. Where there is no comment, it is because the submitter of the sample had none to make.

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National Taiwan University Radiocarbon Measurements II

Radiocarbon ◽

10.1017/s0033822200001259 ◽

1973 ◽

Vol 15 (2) ◽

pp. 345-349 ◽

Cited By ~ 10

Author(s):

Yuin-Chi Hsu ◽

Muh-Chen Chou ◽

Yi-Chuan Hsu ◽

Song-Yun Lin ◽

Shih-Chong Lu

Keyword(s):

Standard Deviation ◽

Oxalic Acid ◽

Proportional Counter ◽

Half Life ◽

Statistical Nature ◽

Radiocarbon Dates ◽

Disintegration Process ◽

Modern Standard

The C14 dates given below have been obtained by counting CO2 at 2 atm pressure in a 1 L proportional counter. Details of procedure are given in our previous list (R., 1970, v. 12, p. 187–192). Radiocarbon dates in this list are based on 95% of activity of NBS oxalic acid as the modern standard and were calculated using 5570 yr as the half-life of C14. Errors quoted with the dates are standard deviation originating from the statistical nature of radioactive disintegration process. Results obtained during 1970 and 1971 are described here.

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