scholarly journals Bratislava Radiocarbon Measurements II

Radiocarbon ◽  
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.

scholarly journals Radiocarbon Dating at the University of Washington III

Radiocarbon ◽  
1966 ◽  
Vol 8 ◽  
pp. 498-506 ◽  
Author(s):  
A. W. Fairhall ◽  
W. R. Schell ◽  
J. A. Young
Keyword(s):  
Standard Deviation ◽  
Oxalic Acid ◽  
Lower Limit ◽  
Half Life ◽  
Radiocarbon Dating ◽  
Isotope Fractionation ◽  
Statistical Error ◽  
Sample Count ◽  
The University ◽  
Made In

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.

scholarly journals Isotopes' Radiocarbon Measurements IX

Radiocarbon ◽  
1972 ◽  
Vol 14 (1) ◽  
pp. 114-139 ◽  
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.

scholarly journals Rudjer Bošković Institute Radiocarbon Measurements VI

Radiocarbon ◽  
1981 ◽  
Vol 23 (3) ◽  
pp. 410-421 ◽  
Author(s):  
Dušan Srdoč ◽  
Adela Sliepčevic ◽  
Bogomil Obelic ◽  
Nada Horvatinčic
Keyword(s):  
Oxalic Acid ◽  
Soil Sample ◽  
Half Life ◽  
Sample Pretreatment ◽  
Radiocarbon Date ◽  
Sample Treatment ◽  
New Techniques ◽  
Counting Technique ◽  
Acid Sample ◽  
Modern Standard

The following radiocarbon date list contains dates of samples measured since our previous list (R, 1979, v 21, p 131-137). As before, age calculations are based on the Libby half-life 5570 ± 30 yr and reported in years before 1950. The modern standard is 0.95 of the activity of NBS oxalic acid. Sample pretreatment, combustion, and counting technique are essentially the same as described in R, 1971, v 13, p 135-140, supplemented by new techniques for groundwater processing (R, 1979, v 21, p 131-137) and for soil sample treatment (R, 1977, v 19, p 465-475).

scholarly journals Vienna Radium Institute Radiocarbon Dates II

Radiocarbon ◽  
1971 ◽  
Vol 13 (1) ◽  
pp. 126-134 ◽  
Author(s):  
Heinz Felber
Keyword(s):  
Proportional Counter ◽  
Half Life ◽  
Sample Pretreatment ◽  
Radium Institute ◽  
Radiocarbon Dates

Measurements have continued with the same proportional counter system, the same procedure in sample pretreatment, methane preparation and measurement, and the same age calculation using a half-life of 5568 ± 30 yr as described previously (R., 1970, v. 12, p. 298–318).

scholarly journals Stockholm Natural Radiocarbon Measurements IV

Radiocarbon ◽  
1962 ◽  
Vol 4 ◽  
pp. 115-136 ◽  
Author(s):  
Lars G. Engstrand ◽  
H. Göte Östlund
Keyword(s):  
Oxalic Acid ◽  
Proportional Counter ◽  
Half Life ◽  
The Third ◽  
Direct Continuation

This paper is a direct continuation of the third dating list (Stockholm III), and the entire technique is virtually unchanged, using one 0.5–1 and one 1.0.1 3 atm CO2proportional counter. Ages are calculated according to the recommendation given in the introduction of this book, and δC13has been measured for unknown samples and for the different CO2preparations of the NBS oxalic-acid standard. Since the numerical relationship between the C14activity of our old oak standard and that of NBS was valid for a δC13value of almost exactly −19 for the NBS preparation in question, it still holds true that all dates given in Stockholm I, II and III can be converted to the new scale by subtracting 55 yr. The NBS preparation St-532 measured by Craig (1961) having a δC13value of −17.2 is only one of several preparations with values between −17 and −20. Age figures are given in C14yr before A.D. 1950; the half life for C14is taken as 5568 ± 30 yr.

scholarly journals University of Michigan Radiocarbon Dates XV

Radiocarbon ◽  
1972 ◽  
Vol 14 (1) ◽  
pp. 195-222 ◽  
Author(s):  
H. R. Crane ◽  
James B. Griffin
Keyword(s):  
Half Life ◽  
Radiocarbon Dating ◽  
Geiger Counter ◽  
University Of Michigan ◽  
Radiocarbon Dates ◽  
Statistical Errors ◽  
Standard Deviations

The following is a list of dates obtained since the compilation of List XIV, and the method is essentially the same. Two CO2–CS2 Geiger counter systems were used. Equipment and counting techniques have been described elsewhere (Crane, 1961). Dates and estimates of error in this list follow the practice recommended by the International Radiocarbon Dating Conference 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 number of counts only. In Michigan date lists up to and including VII, we quoted errors at least twice as great as the statistical errors of counting, to take account of other errors in the over-all process.

scholarly journals Tata Institute Radiocarbon Date List II

Radiocarbon ◽  
1964 ◽  
Vol 6 ◽  
pp. 226-232 ◽  
Author(s):  
D. P. Agrawal ◽  
S. Kusumgar ◽  
D. Lal ◽  
R. P. Sarna
Keyword(s):  
Oxalic Acid ◽  
Proportional Counter ◽  
Half Life ◽  
Radiocarbon Date ◽  
Naoh Pretreatment ◽  
Tata Institute ◽  
Gas Proportional Counter ◽  
Inorganic Fraction

The C14 dates presented here have been obtained by counting acetylene, synthesised from the sample, in an Oeschger-Houtermans’ gas proportional counter. The chemical and counting procedures have been described in some detail (Kusumgar et al., 1963a).Dates are based on the C14 half-life value of 5568 yr. For conversion of b.p. dates to a.d./b.c. scale, a.d. 1950 has been taken as the reference yr. Ninety-five % activity of NBS oxalic acid has been adopted as the value for the pre-1900 age-corrected wood.All samples were treated with dilute HCl. Whenever NaOH pretreatment was possible, it has been mentioned in the date list. In the case of bones, only the inorganic fraction has been dated.

scholarly journals University of Washington Dates IV

Radiocarbon ◽  
1976 ◽  
Vol 18 (2) ◽  
pp. 221-239 ◽  
Author(s):  
A W Fairhall ◽  
A W Young ◽  
J L Erickson
Keyword(s):  
Oxalic Acid ◽  
Proportional Counter ◽  
Counting Rate ◽  
Sea Water ◽  
Differential Pressure ◽  
Dead Volume ◽  
Active Volume ◽  
The Third ◽  
Proportional Counters ◽  
Anticoincidence Counting

The dates reported in this list are for geologic and archaeologic samples only. During the interval since our last date list (R, 1966, v 8, p 498-506) most of our measurements have been on samples of sea water. These will be reported separately at a later time. The methods used are essentially those reported previously (R, 1963, v 5, p 80-81) but with the following notable changes and additions: We now prepare our methane counting gas as described in Buddemeier et al (1970). Our IL membrane counter has since been augmented by 3 additional counters. Two of these are IL quartz proportional counters inside geiger anticoincidence shields. Operating pressures are ca 1.5 to 4atm. Backgrounds of these 2 counters are in the neighborhood of 1.8 and 3cpm and the net counting rate of NBS oxalic acid ranges from 7 to 18.7cpm, depending on the pressure. The third counter (“minicounter”) is rather special: .IL quartz proportional counter inside a methane proportional anticoincidence counter. Sample and anticoincidence counting gases are introduced simultaneously with a differential pressure that never exceeds a few cm Hg. The sample filling side is constructed so as to minimize dead volume; over 80% of the sample gas is inside the active volume of the 14C counter. The range of filling pressures which are possible is ca 1 to 4atm.

scholarly journals University of Michigan Radiocarbon Dates XI

Radiocarbon ◽  
1966 ◽  
Vol 8 ◽  
pp. 256-285 ◽  
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.

scholarly journals University of Michigan Radiocarbon Dates VIII

Radiocarbon ◽  
1963 ◽  
Vol 5 ◽  
pp. 228-253 ◽  
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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