The Organisation of Egyptian Antiquities believes that Egypt should play an important role in current international research in the field of radiocarbon dating of archaeologic samples. Thus, such a laboratory was established within the Center of Research and Conservation of Antiquities, CRCA, Cairo.

The following list of dates contains all measurements made during 1973, ie, since our last list (R, 1973, v 15, p 451–468). We have installed this year a Nuclear Enterprises NIM system to be used with our 2.5L Oeschger-type proportional counter (Philips), in addition to our 6L and 1L proportional counters which have worked consistently with Beckman Lowbeta electronics. The Philips counter has been calibrated relative to the Beckman electronics and we are now calibrating it relative to the NIM system.

Radiocarbon measurements, mainly on soil and water samples are being continued. Benzene samples are prepared as described earlier (Scharpenseel and Pietig, 1969; 1970). Radioactivity is measured in a single quartz vial, and also with 13 specially manufactured, low background Teflon/Duraluminium vials, similar to the system described by Polach (1971, pers commun).

We follow the same method of radiocarbon dating used in the Gif-Sur-Yvette dating laboratory. Samples are inspected and foreign material removed. Wood and charcoal samples are treated with 0.1N ammonium hydroxide and 0.1N hydrochloric acid. Shells are treated with 10% hydrochloric acid to eliminate surface contamination. Bone samples are treated with 0.1N ammonium hydroxide to remove humic acids and 10% HCl to remove inorganic carbonate and retain collagen for radiocarbon measurements. Sample CO2 is produced by combustion in oxygen. The stream of gases passes over CuO at 600°C to insure complete oxidation of C to CO2 and through traps containing, respectively, silver nitrate and sulfuric chromic acid solution for purification; barium carbonate is precipited from barium hydroxide bubblers. After filtering and drying, CO2 is liberated from barium carbonate by sulfuric acid. The CO2 is used to fill a 1.2L steel proportional counter at 740mm Hg. Age calculations are based on a 14C half-life of 5568 ± yr and 0.95 of activity of the NBS oxalic acid standard; ages are quoted in yr before 1950. Finite ages are quoted with 1σ criterion corresponding to the standard deviation based only on counting errors; the maximum age is quoted with 4 σ criterion above background.

The Dublin radiocarbon dating laboratory was operational in 1958 to 1960 and the scintillation counter system used at that time has previously been described (Delaney and McAulay, 1959). The system is now operational again and has been modified to date samples after conversion to benzene. The electronic equipment differs from that previously used only insofar as more compact and drift-free transistorized units are now employed. With these modifications, considerable improvements in sensitivity and accuracy are obtained. 5ml benzene, diluted with a commercial toluene based scintillant is used in a 12.5ml silica cell for the detection of 14C disintegrations. The background count-rate varies inversely with the barometric pressure (ca 2.6% cm–1Hg). The background is ca 3.4cpm, and the detection efficiency is ca 60% and excludes the tritium spectrum.

The Radioisotopes Laboratory was established in January 1972, in order to supply radiocarbon measurements of various samples to several institutions. Active analyses commenced in June following the testing and evaluation of equipment and known samples for accuracy and reproducibility. During this time, data was accumulated for the statistical establishment of counting accuracy, particularly for background activity.

This list comprises age measurements carried out from October 1972 to July 1973. Samples dated are all of archaeologic interest and come from Italian territory. Pretreatment of samples, production of purest CO2 and counting techniques have been described elsewhere (Azzi, 1972; Azzi et al, 1973).

The Low-level Measurements Laboratory at AERE, Harwell was set up some years ago principally to measure natural levels of tritium in water for hydrologic applications. The measurement of 14C in groundwater carbonates was a logical development from this work. In the period 1971–73 the measurement system has been extended to include archaeologic samples and this is the first list of dates for samples submitted during that period.

Most of the 14C measurements reported here were made between October 1972 and October 1973. Equipment, measurement, and treatment of samples are the same as reported previously (R, 1968, v 10, p 36–37; 1970, v 12, p 534).

14C dates listed in this report on geochemical, geologic, and archaeologic samples were obtained mainly from the beginning of 1971 to the middle of 1973. Techniques of measurement used are the same as described previously (Yang, 1972). Sample descriptions and comments for archaeologic samples were prepared in collaboration with collectors and submitters. For age calculation, 95% activity of NBS oxalic acid is used as the modern standard and the value of 5568 ± 40 years is used for the half-life of 14C. Dates are expressed in years bp (before ad 1950). The error (1σ) quoted is calculated from the uncertainty involved in counting background, NBS oxalic acid standard, and sample.

The following date list consists of samples prepared mainly during 1970 and 1971. Some old measurements, not included in previous lists are added. Ages reported here are calculated using the conventional half-life of 14C: 5568 years and NBS oxalic acid as recent standard.

The 14C dates given below are continued from our previous list (R, 1972, v 14, p 223–238), and results obtained mainly during 1971–2 are described. A 2.7L stainless steel counter and a 3.3L copper counter are used as previously, yielding background counting rates of 6.9 and 6.0 cpm, respectively, when filled with dead CO2 at ca 1.8 atm. Dates have been calculated on the basis of the 14C half-life of 5568 yr and 95% of NBS oxalic acid is modern standard. No correction has been made for any of the samples in this list.

This list includes age measurements carried out from January 1972 to December 1973 with previously described CO2-proportional counters (Alessio et al, 1970). All archaeologic and geologic samples but one come from Italian territory.

On two previous occasions we have published lists of 14C results of precisely dated wood samples in Radiocarbon as per mil deviations (R, 1965, v 7, p 179–186; R, 1969, v 11, no. 2, p 469–481). We have also published a list of 14C dates, consolidating all dated wood samples processed in our lab to July 1969 (Ralph and Michael, 1970).

This date list was compiled by the Institute of Geological Sciences (UK) incorporating data supplied under contract by E Welin, Radioactive Dating Laboratory, Stockholm. Unless otherwise stated, age figures are in 14C years before ad 1950. The half-life of 14C is taken as 5568 years and the error, based on counting statistics of sample, background, and modern, is given as one standard deviation. Correction for 13C/12C fractionation has been made.

All samples processed from November 1971 through January 1973 at the Illinois State Geological Survey Radiocarbon Dating Laboratory are reported here. The benzene liquid scintillation technique was used. Laboratory procedures used were the same as those reported by Coleman (1973), with the exceptions that bone collagen was separated by the Longin (1970; 1971) technique and acetylene was trimerized to benzene as described by Coleman, et al (1972).

This date list includes most of the archaeologic and geologic samples dated in this laboratory since publication of our last date list (R, v 13, p 367–381), as well as some samples dated previously, which lacked adequate sample information. Known-age samples are reported in Univ of Pennsylvania Radiocarbon Dates XVI, this issue. The bp ages are based on ad 1950, and have been calculated with the half-life value of 5568 yr. All samples were counted at least twice for periods of not less than 1000 min each. Errors quoted for each sample are derived from the measurement of the sample, the background, and several counts of our mid- 19th century standard Oak sample, but do not include the half-life error. All samples were pretreated with 3N HCL, and some, where noted, were given additional pretreatment with 2% NaOH for the removal of possible humic acid contaminants.

The SMU Radiocarbon Laboratory is operated by the Department of Geological Sciences within the Institute for the Study of Earth and Man. One laboratory room contains the benzene synthesis system where samples are pretreated and converted to CO2 in a standard way and gas is purified after the procedures of Broecker (1957) by passage through hot CuO, 10% AgNO3 solution, chromic acid, hot copper, and P2O5 via cryogenic pumping with liquid nitrogen. Purified CO2 is then converted to Li2C2 which is hydrolized to C2H2 and converted to C6H6 catalytically following the procedures of Noakes et al (1966). Carbon dioxide and benzene yields are routinely in excess of 90% in both cases.

This list includes results of measurements made from 1969 to 1972 in the Natural Radiocarbon Laboratory of the Centre de Recherches Radiogéologiques de Nancy (CRR).

Most of the 14C measurements reported here were made between August 1970 and August 1972. Chemical treatment of samples and counting technique remain as described previously (R, 1968, v 10, p 144–148; 1971, v 13, p 97–102). We have added Houtermans-Oeschger type multi-anode anticoincidence gas proportional counter, manufactured by Tokyo Atomic, Japan. The central counter tube, which has several small holes, 5mm diam, is made of aluminized polyethylene foil, 0.06mm thick, with 72mm inside diam and 300mm sensitive length. The external counter tube is made of stainless steel 4mm thick, with 93mm inside diam and 350mm length. The anode wires of both counters are also made of stainless steel 0.05mm diam. The counters are surrounded by a paraffin shield 50mm thick and encased in a 250mm shield of steel on all sides. Acetylene is used as the counting gas at 753.3mm Hg (22 ± 1°C). Counting rates of background and 95% activity of NBS oxalic acid standard were 1.25 ± 0.02cpm and 14.39 ± 0.12cpm, respectively.