scholarly journals Arizona Radiocarbon Dates VIII

Radiocarbon ◽  
1971 ◽  
Vol 13 (1) ◽  
pp. 1-18 ◽  
Author(s):  
C. Vance Haynes ◽  
Donald C. Grey ◽  
Austin Long
Keyword(s):  
Sample Preparation ◽  
Oxalic Acid ◽  
Half Life ◽  
Isotopic Fractionation ◽  
Radiocarbon Dates ◽  
Carbon Isotopic ◽  
Isotopic Analyses

The carbon isotopic analyses reported here covers the period since the last list (Haynes et al., 1967) until summer 1969. All results relating to secular C14 fluctuations in atmospheric CO2 are now published separately (Damon et al., 1970). Sample preparation and counting procedures remain essentially unchanged since completion of our conversion to CO2 in 1960. All δC13 values are reported relative to PDB and all C14 dates, unless otherwise noted, are based on the 5568 year half-life, but are not corrected for C13 content. 0.95 NBS oxalic acid activity is our routine standard periodically monitored for isotopic fractionation.

scholarly journals Institut Royal du Patrimoine Artistique Radiocarbon Dates II

Radiocarbon ◽  
1971 ◽  
Vol 13 (1) ◽  
pp. 29-31 ◽  
Author(s):  
M. Dauchot-Dehon ◽  
J. Heylen
Keyword(s):  
Oxalic Acid ◽  
Atmospheric Pressure ◽  
Half Life ◽  
Isotopic Fractionation ◽  
Electronic Apparatus ◽  
Radiocarbon Dates ◽  
Unknown Sample ◽  
Preset Time ◽  
Standard Deviations

The method used was described in R., 1968, v. 10, p. 29–35. The counter is the same (M.B.L.E. Houtermans and Oeschger) but the electronic apparatus is new; all is transistorized and the installation operates in preset time. The counter is filled at a pressure of 600 to 1000 mm Hg; sample, modern reference, and background are counted at the same pressure and reduced to standard conditions: 760 mm Hg, 20°C. Atmospheric pressure and temperature are measured at each filling. Samples are counted for 20 hours at one month intervals and a third time if measurements do not agree within two standard deviations. Age calculations are based on a contemporary value equal to 0.95 of activity of NBS oxalic acid standard and 5570 yr for the half-life of C14, 1950 used as reference year. Errors quoted include the standard deviations of the count rates for unknown sample, modern and background; no corrections are made for isotopic fractionation.

scholarly journals Copenhagen Radiocarbon Dates IX

Radiocarbon ◽  
1968 ◽  
Vol 10 (2) ◽  
pp. 295-327 ◽  
Author(s):  
Henrik Tauber
Keyword(s):  
Oxalic Acid ◽  
Half Life ◽  
Isotopic Fractionation ◽  
Radiocarbon Dates ◽  
Unknown Sample ◽  
De Vries ◽  
Standard Deviations

The following list comprises a selected number of measurements made up to October, 1967. Age calculations are based on 95% of the activity of the NBS oxalic-acid standard, and on a half-life for C14 of 5570 yr. Results are reported in yr before 1950, and in the A.D./B.C. scale.Errors quoted include standard deviations of the count rates for the unknown sample, contemporary value, and background. Because possible errors arising from isotopic fractionation in the plants, or from the de Vries effect, have not been included, calculated errors smaller than 100 yr have been increased by rounding to that figure as a minimum.Sample descriptions have been prepared in collaboration with collectors and submitters.

scholarly journals Birbal Sahni Institute Radiocarbon Measurements II

Radiocarbon ◽  
1980 ◽  
Vol 22 (1) ◽  
pp. 54-60 ◽  
Author(s):  
G Rajagopalan ◽  
Vishnu Mittre ◽  
B Sekar
Keyword(s):  
Oxalic Acid ◽  
Half Life ◽  
Isotopic Fractionation ◽  
Counting System ◽  
Radiocarbon Dates ◽  
Counting Statistics

The radiocarbon dates covered in this list were measured during 1978. Chemical and counting procedures are as reported previously (R, 1978, v 20, p 398-404). Age calculations are based on the conventional 14C half-life (5570 yr) and on the contemporary value of 95% of the activity of NBS oxalic acid. Errors quoted correspond to 1σ value which takes into account the counting statistics, the uncertainty in the half-life, and the instability of the counting system. The ages are not corrected for isotopic fractionation in nature.

scholarly journals Birbal Sahni Institute Radiocarbon Measurements III

Radiocarbon ◽  
1982 ◽  
Vol 24 (1) ◽  
pp. 45-53 ◽  
Author(s):  
G Rajagopalan ◽  
B Sekar Vishnu-Mittre ◽  
T K Mandal
Keyword(s):  
Oxalic Acid ◽  
Half Life ◽  
Isotopic Fractionation ◽  
Counting System ◽  
Radiocarbon Dates ◽  
Counting Statistics

The radiocarbon dates reported in this date list cover the measurements carried out in 1979 to 1980. Chemical and counting procedures are the same as reported earlier (R, 1978, v 20, p 398–404). Age calculations are based on the conventional 14C half-life (5570 yr) and on the contemporary value of 95% of the activity of NBS oxalic acid. Errors quoted correspond to 1σ value which takes into account the counting statistics, the uncertainty in the half-life, and the instability of the counting system. The ages are not corrected for isotopic fractionation in nature.

scholarly journals Copenhagen Radiocarbon Dates VII

Radiocarbon ◽  
1966 ◽  
Vol 8 ◽  
pp. 213-234 ◽  
Author(s):  
Henrik Tauber
Keyword(s):  
Oxalic Acid ◽  
Half Life ◽  
Isotopic Fractionation ◽  
Radiocarbon Dates ◽  
Unknown Sample ◽  
De Vries ◽  
Standard Deviations

The following list comprises a selected number of measurements made up to November, 1965. Age calculations are based on a contemporary value equal to 95% of the activity of the NBS oxalic-acid standard, and on a half life for C14 of 5570 yr. Results are reported in years before 1950, and in the A.D./B.C. scale. Errors quoted include the standard deviations of the count rates for the unknown sample, the contemporary value, and the background. Because possible errors arising from isotopic fractionation in the plants, or from the de Vries effect, have not been included, calculated errors smaller than 100 yr have been increased by rounding to that figure as a minimum.

scholarly journals University of Granada Radiocarbon Dates III

Radiocarbon ◽  
1986 ◽  
Vol 28 (3) ◽  
pp. 1200-1205 ◽  
Author(s):  
Cecilio Gonzalez-Gomez ◽  
Purificacion Sanchez-Sanchez ◽  
Elena Villafranca-Sanchez
Keyword(s):  
Sample Preparation ◽  
Oxalic Acid ◽  
Half Life ◽  
Radiocarbon Dating ◽  
Standard Sample ◽  
Research Project ◽  
Radiocarbon Dates ◽  
Preparation Techniques ◽  
Age Determinations ◽  
Modern Standard

The following list includes some measurements made from December 1982 to May 1985 in the Radiocarbon Dating Laboratory, Faculty of Science, University of Granada, of samples from Spain, Portugal, and the Sudan. Sample preparation techniques and benzene synthesis remain as described previously (R, 1982, v 24, p 217–221) and equipment and measurement of samples was also reported previously (R, 1985, v 27, p 610–615). Radiocarbon ages are calculated using the 14C half-life of 5570 years and 0.95 activity of NBS oxalic acid is used as modern standard. Sample descriptions are based on information provided by submitters. Age determinations were made with the help of Research Project 0925/81, CAICYT, Spain.

scholarly journals UCLA Radiocarbon Dates IV

Radiocarbon ◽  
1965 ◽  
Vol 7 ◽  
pp. 336-371 ◽  
Author(s):  
Rainer Berger ◽  
G. J. Fergusson ◽  
W. F. Libby
Keyword(s):  
Sample Preparation ◽  
Oxalic Acid ◽  
Half Life ◽  
Count Rate ◽  
Radiocarbon Dates ◽  
New Methods ◽  
Counting Procedure ◽  
Energy Channels ◽  
Modern Standard

The measurements reported in this list have been carried out in the Isotope Laboratory of the Institute of Geophysics and Planetary Physics during 1964. They are a continuation of the previously reported date lists UCLA I, II and III. The same counting procedure has been continued: CO2 proportional counting at 1 atm of pressure in a 7.5 L counter with three energy channels. Dates have been calculated according to the recommendations of the Fifth Radiocarbon Conference, Cambridge, 1962, on the basis of a radiocarbon half-life of 5568 yr (Godwin, 1962). The modern standard for organic samples has been based on 95% of the count rate of NBS oxalic acid for radiocarbon laboratories. Background measurements are determined with CO2 derived from marble. The ages of carbonate-containing substances such as shells and tufa have been calculated on the basis of estimates for the corresponding contemporary C14 activity (Broecker and Walton, 1959), as discussed in the respective sample descriptions. New methods of sample preparation are described in context with the date listings.

scholarly journals Copenhagen Radiocarbon Dates VI

Radiocarbon ◽  
1964 ◽  
Vol 6 ◽  
pp. 215-225 ◽  
Author(s):  
Henrik Tauber
Keyword(s):  
Oxalic Acid ◽  
Half Life ◽  
Radiocarbon Dates ◽  
Unknown Sample ◽  
Minimum Sample ◽  
Standard Deviations

The following list comprises a selected number of measurements made up to November 1963. Age calculations are based on a contemporary value equal to 95% of the activity of the NBS oxalic-acid standard, and on a half life for C14 of 5570 ± 30 yr.Results are expressed in years before 1950 and in the b.c.-a.d. scales. Errors quoted include the standard deviations of the count rates for the unknown sample, the contemporary value, and the background. Calculated errors smaller than 100 yr have been increased by rounding to that figure as a minimum. Sample descriptions have been prepared in collaboration with collectors and submitters.

scholarly journals University of Miami Radiocarbon Dates XVI

Radiocarbon ◽  
1979 ◽  
Vol 21 (3) ◽  
pp. 477-483
Author(s):  
D S Introne ◽  
R Johnson ◽  
J J Stipp
Keyword(s):  
Standard Deviation ◽  
Half Life ◽  
Isotopic Fractionation ◽  
Radiocarbon Dates ◽  
Marine Carbonates ◽  
Age Correction ◽  
University Of Miami ◽  
Reservoir Age ◽  
Modern Standard

Radiocarbon measurements have been continued on a variety of projects and materials. Chemical and counting procedures remain the same as indicated in R, v 20, p 274-282. Dates are calculated using the Libby 14C half-life of 5568 years; errors are reported as one-standard deviation (1σ) based only on statistical counting uncertainties in background, modern standard, and sample activities. All samples for which 13C/12C ratios are available are corrected for isotopic fractionation by normalizing to —25‰. A 400-year reservoir age correction has been applied to marine carbonates.

scholarly journals Tallinn Radiocarbon Dates VI

Radiocarbon ◽  
1980 ◽  
Vol 22 (1) ◽  
pp. 91-98 ◽  
Author(s):  
J M Punning ◽  
R Rajamäe ◽  
K Joers ◽  
H Putnik
Keyword(s):  
Oxalic Acid ◽  
Half Life ◽  
Radiocarbon Dates ◽  
Academy Of Sciences ◽  
Modern Standard

The following list includes samples dated at the Institute of Geology, Academy of Sciences of the Estonian SSR in 1978. The measurement of natural 14C activity is performed by 1-channel and 2-channel scintillation devices (Punning & Rajamäe, 1977). Ages are calculated using the half-life of 5568 ± 30 years and 0.95 NBS oxalic acid modern standard with ad 1950 as reference year.

Sign in / Sign up

Export Citation Format

Share Document