scholarly journals Instituto Venezolano de Investigaciones Cientificas Natural Radiocarbon Measurements III

Radiocarbon ◽  
1967 ◽  
Vol 9 ◽  
pp. 237-245 ◽  
Author(s):  
M. A. Tamers
Keyword(s):  
Oxalic Acid ◽  
Count Rate ◽  
Radiocarbon Dating ◽  
Liquid Scintillation ◽  
Liquid Scintillation Spectrometer ◽  
Modern Standard

The dates reported here represent a portion of those determined in 1966, The Radiocarbon Dating Laboratory of the Instituto Venezolano de Investigaciones Científicas carries out a synthesis of benzene for each sample and detects the activity with a liquid scintillation spectrometer. For routine measurements, 3 cc synthesized benzene and 1 cc commercial toluene, with PPO and dimethyl-POPOP scintillators, are used in a special small counting vial. The modern standard is 95% of the NBS oxalic acid, which gives a net modern count rate of 23.9 cpm. The background is now 8.5 cpm.

scholarly journals University of Miami Radiocarbon Dates II

Radiocarbon ◽  
1975 ◽  
Vol 17 (1) ◽  
pp. 112-120 ◽  
Author(s):  
J J Stipp ◽  
K L Eldridge
Keyword(s):  
Oxalic Acid ◽  
Half Life ◽  
Liquid Scintillation ◽  
Liquid Scintillation Spectrometer ◽  
Radiocarbon Dates ◽  
Laboratory Procedures ◽  
University Of Miami ◽  
Modern Standard

The following list of dates are selected from geologic and archaeologic samples measured in late 1973. The laboratory procedures and techniques are the same as indicated in R, 1974, v 16, p 402–408, where sample is synthesized to benzene and counted for 24 hours in either a Beckman LS-100-C or Packard 2311 liquid scintillation spectrometer. Ages are calculated relative to 0.95 x NBS oxalic acid using a 14C half-life of 5568 years. The quoted error is 1σ, which includes only the counting uncertainties of the background, modern standard, and sample. Sample descriptions and comments were written in collaboration with collectors and submitters.

scholarly journals Precise 14C Measurement By Liquid Scintillation Counting

Radiocarbon ◽  
1979 ◽  
Vol 21 (1) ◽  
pp. 1-21 ◽  
Author(s):  
Gordon W Pearson
Keyword(s):  
Liquid Scintillation Counting ◽  
Count Rate ◽  
Radiocarbon Dating ◽  
Liquid Scintillation ◽  
Scintillation Counting ◽  
Reference Standard ◽  
Standard Material ◽  
Image Position

Radiocarbon dating involves a comparison of the count rate of sample carbon with that of modern reference standard material. To calculate a date the ratio Z must be determined where

scholarly journals University of Texas At Austin Radiocarbon Dates XIII

Radiocarbon ◽  
1979 ◽  
Vol 21 (2) ◽  
pp. 257-273 ◽  
Author(s):  
S Valastro ◽  
E Mott Davis ◽  
Alejandra G Varela
Keyword(s):  
Oxalic Acid ◽  
National Science Foundation ◽  
Liquid Scintillation ◽  
Scintillation Counting ◽  
Radiocarbon Dates ◽  
University Of Texas ◽  
National Science ◽  
Sample Count ◽  
Counting Statistics ◽  
Modern Standard

This list reports certain 14C measurements completed by November 1978; other projects completed by this time will be reported later. Age calculations are based on 14C half-life of 5568yr and modern standard of 95% NBS oxalic acid, supplemented by tree rings of pre-industrial wood from a log cut in the 1850's (Tx-540; R, 1970, v 12, p 249). Deviations reported are based on counting statistics of sample, background and modern, and are ± 1σ, except that when sample count approaches either modern or background, 2σ limits are reported. Unless noted, 12C/13C measurements were not made and results are not corrected for 13C fractionation (assumed ratio = −25‰ WRT PDB). Our laboratory uses liquid scintillation counting of benzene, with Li2C2 and vanadium-activated catalyst in preparation; chemical yields range between 95% and 99%. Three counters are employed; a Packard Tri-Carb Model 3002 and 2 Beckman LS320 spectrometers obtained through a grant from the National Science Foundation.

scholarly journals Tartu Radiocarbon Dates XIII

Radiocarbon ◽  
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.

scholarly journals Newly Designed 0.8-ML Teflon® Vial for Microvolume Radiocarbon Dating

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 743-747 ◽  
Author(s):  
Michael Buzinny ◽  
Vadim Skripkin
Keyword(s):  
Significant Influence ◽  
Count Rate ◽  
Radiocarbon Dating ◽  
Figure Of Merit ◽  
Liquid Scintillation ◽  
Detection Efficiency ◽  
Operational Parameters ◽  
Counting Period ◽  
Background Count ◽  
Background Count Rate

We have tested two versions of an 0.8-ml volume Teflon® vial, designed specifically for radiocarbon dating in the microvolume range, using a modern Quantulus 1220™ liquid scintillation (LS) spectrometer. We determined the counting performance of each vial type in conjunction with different designs of copper holder, viz., with and without the incorporation of a “Teflon® light coupler”. We also compared the losses of sample benzene during a typical 28-day counting period. Results show that neither vial design nor the type of vial holder used in the intercomparison had a significant influence on counting performance. We recorded an absolute 14C detection efficiency of 82% against a background count rate of 0.1 cpm, i.e., a “figure of merit (FM) value” = 67,240. This compares favorably with the operational parameters anticipated for microvolume 14C dating by modern LS spectrometry. However, variations in the design of the sealing method used between the vial types was reflected in an apparent approximate tenfold difference in the amount of benzene lost during routine counting. In the better case, the evaporation loss was equivalent to 0.032 mg of benzene per day.

scholarly journals University of Texas at Austin Radiocarbon Dates XII

Radiocarbon ◽  
1978 ◽  
Vol 20 (2) ◽  
pp. 245-273 ◽  
Author(s):  
S Valastro ◽  
E Mott Davis ◽  
Alejandra G Varela
Keyword(s):  
Oxalic Acid ◽  
National Science Foundation ◽  
Liquid Scintillation ◽  
Scintillation Counting ◽  
Radiocarbon Dates ◽  
University Of Texas ◽  
National Science ◽  
Sample Count ◽  
Counting Statistics ◽  
Modern Standard

This list reports certain 14C measurements completed by November 1977; other projects completed by this time will be reported later. Age calculations are based on 14C half-life of 5568yr and modern standard of 95% NBS oxalic acid, supplemented by tree rings of pre-industrial wood from a log cut in the 1850's (Tx-540; R, 1970, v 12, p 249). Deviations reported are based on counting statistics of sample, background, and modern, and are ±1σ, except that when sample count approaches either modern or background, 2σ limits are reported. Unless noted, 12C/13C measurements were not made and results are not corrected for 13C fractionation. Our laboratory uses liquid scintillation counting of benzene, with Li2C2 and vanadium-activated catalyst in preparation; chemical yields range between 95% and 99%. Three counters are employed: a Packard Tri-Carb Model 3002 and 2 Beckman LS320 spectrometers obtained through a grant from the National Science Foundation.

scholarly journals University of Granada Radiocarbon Dates V

Radiocarbon ◽  
1991 ◽  
Vol 33 (3) ◽  
pp. 367-373 ◽  
Author(s):  
Cecilio Gonzalez-Gomez ◽  
Purificacion Sanchez-Sanchez
Keyword(s):  
Liquid Scintillation Counting ◽  
Radiocarbon Dating ◽  
Liquid Scintillation ◽  
Scintillation Counting ◽  
Boiling Temperature ◽  
Liquid Scintillation Spectrometer ◽  
Radiocarbon Dates ◽  
Standard Acid ◽  
Basic Procedure ◽  
The University

This paper includes some determinations of archaeological, art and palaeobotanical samples from Spain and Portugal, obtained at the University of Granada Radiocarbon Dating Laboratory, mostly from 1986 to 1988. Pretreatment of charcoal and wood samples is a standard acid-basic procedure using 8% HC1 and 2% NaOH at boiling temperature. The collagen of bone samples is obtained by the Longin (1971) method.The method of dating is benzene synthesis and liquid scintillation counting as previously reported (González-Gómez, López-González & Domingo-García 1982; González-Gómez, Sánchez-Sánchez and Domingo-García 1985; González-Gómez, Sánchez-Sánchez and Villafranca-Sánchez 1986, 1987).14C activity was measured in a Packard Tri-Carb Mod 4640 liquid scintillation spectrometer, using 20 ml low 40K counting vials with 5 ml benzene and 10 ml PPO-toluene as scintillator with a background of ca. 9 cpm. Efficiency was approximately 70% using the part of spectrum above the end point of tritium.

scholarly journals University of Texas at Austin Radiocarbon Dates XIV

Radiocarbon ◽  
1980 ◽  
Vol 22 (4) ◽  
pp. 1090-1115 ◽  
Author(s):  
S Valastro ◽  
E Mott Davis ◽  
Alejandra G Varela ◽  
Carolyn Ekland-Olson
Keyword(s):  
Oxalic Acid ◽  
National Science Foundation ◽  
Liquid Scintillation ◽  
Scintillation Counting ◽  
Radiocarbon Dates ◽  
University Of Texas ◽  
National Science ◽  
Sample Count ◽  
Counting Statistics ◽  
Modern Standard

This list reports certain 14C measurements completed by December 1979; other projects completed by this time will be reported later. Age calculations are based on 14C half-life of 5568 yr and modern standard of 95% NBS oxalic acid, supplemented by tree rings of pre-industrial wood from a log cut in the 1850's (Tx-540; R, 1970, v 12, p 249). Deviations reported are based on counting statistics of sample, background and modern, and are ± 1σ, except that when sample count approaches either modern or background, 2σ limits are reported. Unless noted, 12C/13C measurements were not made and results are not corrected for 13C fractionation (assumed ratio = −25‰ WRT PDB). Our laboratory uses liquid scintillation counting of benzene, with Li2C2 and vanadium-activated catalyst in preparation; chemical yields range between 95% and 99%. Three counters are employed; a Packard Tri-Carb Model 3002 and 2 Beckman LS230 spectrometers obtained through a grant from the National Science Foundation.

scholarly journals University of Texas at Austin Radiocarbon Dates VII

Radiocarbon ◽  
1970 ◽  
Vol 12 (1) ◽  
pp. 249-280 ◽  
Author(s):  
S. Valastro ◽  
E. Mott Davis
Keyword(s):  
Oxalic Acid ◽  
Liquid Scintillation Counting ◽  
Liquid Scintillation ◽  
Scintillation Counting ◽  
Radiocarbon Dates ◽  
University Of Texas ◽  
Sample Count ◽  
Counting Statistics ◽  
Made In ◽  
Modern Standard

This list reports C14measurements made in dating projects completed in the year ending December, 1968, and some measurements for projects still in progress. Age calculations are based on C14half-life of 5568 yr and a modern standard of 95% of NBS oxalic acid. Deviations reported are based on counting statistics of sample, background, and modern, and are ±1σ except that when sample count approaches either modern or background, 2σ limits are reported. The laboratory uses liquid scintillation counting of benzene, with Li2C2and vanadium activated catalyst in preparation, as described in Texas IV (Radiocarbon, 1966, v. 8, p. 453–466) and earlier lists. Chemical yields average 85%.

scholarly journals Washington State University Natural Radiocarbon Measurements I

Radiocarbon ◽  
1968 ◽  
Vol 10 (2) ◽  
pp. 479-498 ◽  
Author(s):  
Roy M. Chatters
Keyword(s):  
Oxalic Acid ◽  
Half Life ◽  
Radiocarbon Dating ◽  
Washington State ◽  
State University ◽  
Engineering Research ◽  
Washington State University ◽  
Research Division ◽  
College Of Engineering ◽  
Modern Standard

The College of Engineering Research Division radiocarbon dating laboratory began operating in November 1962 employing a Sharp Laboratories, Inc., CDL-14 system based upon the methane method of Fairhall, Shell, and Takashima (1961).Dates reported herein are calculated using a 5568 yr C14 half-life. The modern standard is taken as 95% of the NBS oxalic acid C14 standard which is converted to CO2 followed by conversion to CH4 in the manner of Fairhall et al. The errors quoted are the 1 σ statistical errors.

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