The following date list includes archaeologic and geologic samples dated by Gif Radiocarbon Laboratory mostly from 1973 to 1975. Volcanic samples reported here were dated up to 1981. Measurements were made in the same manner as previously reported (R, 1972, v 14, p 280). For undersized samples, a 0.1L CO2 proportional counter was used with 5000-minute standard measurements. Ages listed are conventional 14C ages based on the 5568-year Libby half-life; uncertainties are 1σ statistical standard error. Results are based on 95% of NBS oxalic acid activity. Some dates have been calibrated using the correction curve of Klein et al (1982).

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.

C14 dates reported below were obtained mainly at the end of 1968 and during 1969 on archaeologic and geologic samples. Techniques of measurement used are unchanged. Since 1968, 4 complete routine sets have been running, each equipped with a 1 L CO2 proportional counter. One is made of stainless steel with a background of 2.70 cpm at pressure 1 atm and the others are of OFHC copper with a background of either 1.10 or 1.30 cpm for a corresponding pressure of, respectively, 1 or 2 atm. For age calculation, 95% activity of NBS oxalic acid is used as the modern standard and the value of 5570 ± 30 years is used for the half-life of C14. Dates are expressed in years b.p. (before a.d. 1950).

This list consists mainly of dates obtained from analysis during 1967 and 1968 of archaeologic and geologic samples. The last section deals essentially with climatic, palynologic, and sea level variation problems. All measurements of atmospheric CO2 made periodically from 1962 until end of 1970 are also published here. In agreement with international convention, all dates have been calculated on the basis of the C14 half-life of 5568 years and 95% of NBS oxalic acid as the modern reference year.

The list given below contains the C14 dates obtained for only archaeologic samples, during 1966 and 1967; for the study of the geologic samples dated during the same period, cf. our previous list Gif-III (Radiocarbon, 1969, v. 11, p. 327-344). The same instruments and techniques have been employed.

The dates detailed below are a selection of C14 dates obtained from February 1966 to December 1967 for geologic samples. The method is essentially the same as described previously in Radiocarbon, 1966, v. 8 p. 74-95. All samples were subjected to pretreatment, differing in individual cases, to remove contamination. On one of our three installations, modern transistorized equipment replaced the original electronics.

All dates reported have been calculated on the assumed half-life of 5568 yr for C14, and of 1950 as the reference year.

The C14 dating laboratories of Saclay (Saclay I, 1964 and Saclay II, 1965) and Gif (Gif-sur-Yvette, 1966) have joined together under the name of Gif C14 Dating Laboratory. The first series of dating results appears here with code designation Gif, Sa now being obsolete.

The list of dates grouped below represents datings made during 1963. The method and the counting techniques have been previously described (Radiocarbon, v. 6, Saclay I).

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.