The following list shows the age measurements carried out at Saclay by the Service d'Electronique Physique, using the C14 method.

The apparatus employed was completed and calibrated in 1956 and the first tests were performed during the same year. The counting unit is a 1.2 L stainless steel proportional counter and the filling gas is pure CO2 at 74 cm Hg pressure. The shield consists of 20 cm of lead, 10 cm of iron, a coincidence ring and 2 cm of bismuth. The background is 4.86 ± 0.05 counts/min. (Error is ± σ, the duration of each counting being 24 hours.) Final purification is performed by adsorption of CO2 on alumina at low temperature, followed by desorption at room temperature; this has proved particularly effective and gives a very good filling gas. Technique was described in detail previously by the authors (Perquis, Delibrias, and David, 1956; Delibrias and Perquis, 1958).

As a modern carbon standard we first used wood taken from the 1930 to 1945 rings of a large Douglas fir; this standard gave a net count of 6.02 counts/min. This activity, taking into account a 2% Suess-effect for this wood, was found to be 95% of the activity of the NBS oxalic-acid standard, measured in the same counter.

The NBS standard has been adopted by this laboratory since January 1961, and values given here are calculated from this new standard.

Measurements listed are dates obtained from 1956 through 1962. No reports are given here from other types of measurements carried out at Saclay, such as: (1) C14 content of wild plants growing in the vicinity of nuclear reactors; (2) measurement of C14 in blood proteins of workers of the radioactive-tracers industry; (3) Spallation cross-sections for C14 production in oxygen and iron by high energy protons; (4) C14 content of meteorites.

The following list covers the measurements in our institute from January 1962 to March 1963. Sample preparation and conversion into acetylene are described by Wendt, Schneekloth and Budde (1962).

An Oeschger counter with an effective volume of 1.5 L came into operation in 1962. It is shielded by 4 cm of iron and 10 cm of lead. The background amounts to 2.24 cpm, the standard C14 counting-rate 17.05 cpm. In routine measurements, the impure acetylene, after a four-week storing period, is put into the counters. Examination of purity of the gas is carried out by means of an external Cs137 source. In case the gas shows bad plateau characteristics, it is converted by a new process into ethane, using H2 and a palladium catalyst. Thereby, the plateau characteristics improve considerably. The 50%-voltage then is 200 v lower, the slope of the plateau only amounts to 0.2 %/100 v (with external source), and the plateau length increases from 600 v to 1200 v. The additional work amounts to 1/2 hour.

The following list presents dates obtained on a fraction of the total number of measurements made during the years 1962 and 1963 and measurements made previously for which sample data has been recently received. The results which do not appear are withheld pending additional information, or at the request of clients.

This date list covers mainly the datings done in 1962 and 1963 and is therefore a continuation of our last date list (Trondheim III).

The following list covers most of the samples measured at the Uppsala C14 laboratory since the last list (Uppsala III) except for all the samples utilized for determining the increase of the C14/C12 ratio due to explosion of nuclear devices and the few samples measured with a new proportional counter.

The technique used is the same as previously described by Olsson (1958) and the pretreatment is that which has been used earlier (wood, charcoal, peat, gyttja and other organic sediments are boiled with HC1, 1 to 2%, washed with distilled water, kept in NaOH, 1 to 2%, at +80°C over night, washed with distilled water and finally acidified to pH about 3 before being dried) except for Foraminifera tests, see below.

The reference sample is 95% of the activity of the NBS oxalic-acid standard. Any corrections for apparent water ages are thus not included here, but will be discussed in later papers dealing with the marine samples. Corrections for deviations from the normal C13/C12 ratio (-2S.0% in the PDB scale) are applied for the unknown samples. Our oxalic acid was measured by Craig (1961) and has a C13/C12 ratio of -18.97% and corresponds to the accepted standardized value, -19%, which should be used for age determinations (Editorial Statement in Radiocarbon, v. 3). Two new combustions of oxalic acid have not shown any significant difference in their C13 content relative to the oxalic acid 1 sample measured by Craig.

The value 5570 yr has been used for the half-life of C14. Results are expressed in years before 1950 (b.p.). Errors include the standard deviations (a) of the counted particles as well as the error in the δC13 values. When the activity is very low, so that 2σ corresponds to a possibility of infinite age, 2σ has been used instead of σ.

Several samples had to be diluted with CO2 from an old source to bring them to the normal working pressure of 3 atm.

The C14 Laboratory of the German Academy of Sciences of Berlin (DAW) began to obtain dates in 1961. The focus of research is in archaeology. Samples, coll. in close collaboration with the DAW's Institut für Vor- und Frühgeschichte, are mainly from the Neolithic of central and southeastern Europe, and contribute to the continuing discussion (Milojčić, 1961; Müller-Beck, 1961) of the chronology of this period.

The measurements reported in this list have been made in the Isotope Laboratory of the Institute of Geophysics during 1963 and are a continuation of the work reported previously (UCLA I and UCLA II). The same counting procedure—CO2 proportional counting at 1 atm pressure in a 7.5 L counter with three energy channels—continues in use. No barometric effect on the background has been observed, presumably because of the combination of fairly constant barometric pressure in this area and the location of the equipment on the ground floor of a five storey building. Dates continue to be calculated on the basis of a C14 half life of 5568 yr according to the decision of the 1962 Cambridge Conference (Godwin, 1962). The modern standard has been taken as 95% of NBS oxalic acid for all organic samples, while for carbonate material such as shells and tufa, dates have been computed on the basis of estimates of the corresponding contemporary C14 activity (Broecker and Walton, 1959) as indicated in the description accompanying the results.

Installation of a Sharp CDL-14 Carbon-Dating Laboratory was completed at Ohio Wesleyan University in June, 1962. The unit includes a sample conversion system constructed by Radiochemistry, Incorporated for the conversion of carbonaceous samples to the counting gas, methane. Counting equipment consists of a modified Sharp Low Beta system with a 6kv power supply and dual printout registers which automatically blank the counting circuits for 0.1 min for each 100-min printout. The detector has a sensitive volume of 0.5 L and is housed in a shield consisting of 8 in. of lead, 1 in. of steel, and 1 in. of mercury. Anticoincidence is provided by a cylindrical 2-L detector containing 16 anodes and filled with petroleum-generated methane to a pressure of 96 cm Hg.

This date list mainly contains results obtained for archaeological samples which were measured in the Groningen laboratory in the course of the years and which have not hitherto been published in a similar form. As such it is an extension of the previous date list (Groningen IV) and reference is made to this publication for information on the method of presentation, the corrections applied, etc. Samples which are primarily of geological significance will be presented separately in next year's list.