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The Radiocarbon Dating Laboratory was established in 1967 at the Department of Nuclear Physics, Comenius University, as part of a program of low level counting research of the department and as a contribution to geophysical, geologic, archaeologic and hydrologie research.
The following list of dates contains all measurements made during 1972, i.e., since our last list. Counting equipment, operating procedures and sample pretreatment are the same as previously described (R., 1969, v. 11, p. 263). Age calculations are based on 95% activity of the NBS oxalic acid standard 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.
The U.S. Geological Survey, at the Denver Federal Center, Lakewood, Colorado assays C14 concentration of water samples using liquid scintillation techniques. The laboratory synthesizes benzene from precipitated barium carbonate using techniques described by Noakes, Kim, and Akers (1967). Three ml of the synthesized benzene is pipetted into a tared, low potassium-40 glass vial. The sample is weighed and 1ml of a scintillation solution is added to the vial. The scintillation solution used is a mixture of 10g PPO and 0.025g dimethyl-POPOP scintillators in 250ml toluene. Calculations of dates are made with the radiocarbon half-life of 5568 years; plus or minus numbers quoted herein are the standard error for the counting of radioactive disintegrations.
This list presents results obtained during 1971-1972 and is a continuation of research evaluating natural C14 levels for which data have been published previously (Baxter et al., 1969; Baxter and Walton, 1970; Farmer et al., 1972). The results of these studies are presented as δC14 and Δ values based on age-corrected activities, although this correction is very small. Errors quoted are lσ counting uncertainties only. Pretreatment procedures are outlined in the text and analytical methods are essentially unchanged. Gas proportional counting of CH4 in a 0.5L detector is employed (Baxter et al., 1969). Mass spectrometric analyses are performed to a precision of 0.1‰ (± 2σ) on a V.G. Micromass 602B stable isotope mass spectrometer.
Most of the C14 measurements reported here were made between October 1971 and October 1972. Equipment, measurement, and treatment of samples are the same as reported previously (R., 1968, v. 10, p. 36-37; 1970, v. 12, p. 534).
The dates presented here comprise results obtained since our last list (R., 1973, v. 15, p. 156-164). Pure carbon dioxide prepared from the samples is used to fill copper proportional counters at two atmospheres pressure. The detectors are protected from environmental radiation by a massive lead shield inside which, and completely surrounding the proportional counters, is a high efficiency plastic scintillation anticoincidence screen (Switsur, Hall, and West, 1970). Modern sample gas is obtained from combustion of a.d. 1845 to 1855 rings of an oak tree grown near Cambridge, felled in 1950. Background samples are prepared from Welsh anthracite or Connemara limestone. The contemporary standard is compared frequently with the activity of NBS oxalic acid international standard. Age calculations are based on the 14C half-life of 5568 years and the uncertainty stated as one standard deviation calculated from the statistical analysis of sample and standard counting rates.
The following list of dates was compiled since 1971, (R., 1971, v. 13, p. 420-431). Procedures of measurements are essentially unchanged from those reported previously (R., 1964, v. 6, p. 31-36; 1966, v. 8, p. 423-429; 1971, v. 13, p. 420-431).
The Radiocarbon Laboratory at the Scottish Universities Research and Reactor Centre was established in August 1971. The laboratory is funded by the Natural Environment Research Council and its main function is geochemical investigations in collaboration with the component bodies of the Council and with grant-aided associations. A dating service is also provided to others.
This list describes samples dated in this laboratory from January to November, 1972. Operating principles are as previously reported (Gillespie et al. 1972) using synthesized benzene for liquid scintillation counting. Ages are calculated using 0.95 NBS oxalic acid standard with reference to a.d. 1950 using Libby 5570 year half-life.
In this date list we present dates from some very important archaeologic and Quaternary sites. For the first time the temporal spread of the Neolithic cultures of Bihar and the transformation of the Harappa culture in Gujarat has been dated. Some of the sites of controversial antiquity in Pakistan and India also have now been unambiguously dated.
Preparations for determining absolute age by the radiocarbon method were started at the Institute of Geology, Academy of Sciences of the Estonian SSR in 1971. Dating of samples has been carried out since 1972.
Ages reported in this date list are calculated using the Libby half life of 5568 ± 30 years with 1950 as the standard year of reference; results are quoted in years b.p. and on the a.d./b.c. time scale.
The dating equipment and operating conditions remain essentially as previously described. This list includes some small samples counted at a filling pressure equivalent to 76cm Hg. at 20°C. Carbon isotope ratios were obtained and calculated as described (R., 1973, v. 15, p. 212). All samples are from Ireland.