The radiocarbon dating laboratory in the Institute of Marine Science at the University of Alaska was established in the fall of 1968 and became operational a year later. Most of the samples examined have been from Alaska and consist largely of wood and peat.

The following list of dates contains the majority of measurements made during 1975, ie, since our last list (R, 1975, v 17, p 255-275).

The radiocarbon dating laboratory was set up during 1972 and 1973 with financial support of the FKFO (Fonds voor Kollektief Fundamenteel Onderzoek) Belgium, to enable us to place Upper Pleistocene and Holocene sediments in their correct stratigraphic position. Dating of samples began in the middle of 1974.

The following list consists entirely of dates for archaeologic samples from the British Isles measured since about mid-1970 up to June 1974*. The dates were obtained by liquid scintillation counting of benzene using a Model 3315 Packard Tricarb Liquid Scintillation Spectrometer. In general, procedures are as described in the previous date list (R, 1971, v 13, p 157; see also Burleigh, 1972). However, data processing was improved by means of a real-time link with a Hewlett Packard 2100A computer having 32K of core, which accepts readings from the counter at the end of each individual counting period. The computer monitors the accumulated sample counts and reports when the statistical error terms of these have reached previously chosen limits; final dates are then obtained on supplying the appropriate benzene sample weights and isotopic fractionation values. The system maintains a permanent record of all the data obtained from measurement of samples and reference standards and gives warning of any serious changes in counter performance. A full description of the capabilities of this system is given elsewhere (Hall and Hewson, in press). Finally, improvements were made to the bomb used for initial combustion of sample materials (Burleigh, 1974) and a new, stainless-steel, lithium reaction furnace (similar to that described by Polach and Stipp, 1967) was recently installed.

Radiocarbon measurements are carried out mainly on soil samples and soil organic matter fractions. Benzene samples are prepared as described earlier (Scharpenseel and Pietig, 1969; 1970). Radioactivity is measured in a single quartz vial, using a Packard Tri Carb Model 3075 as well as a Berthold Betascint BF 5000. Most equipment has been transferred from Bonn University Radiocarbon Dating Lab to Hamburg, where operation of former Bonn Radiocarbon Lab will be continued.

The analytical facilities at Glasgow have been extended to include gas proportional (CO2 and CH4) and liquid scintillation (C6H6) counting laboratories. The results presented here were obtained during 1972-1974 using the CO2 gas counting system only. In brief, organic samples, after pretreatment as described in the text, are burned in a tube combustion unit and the evolved CO2 absorbed in KOH solution. BaCO3 is precipitated and acid-hydrolyzed in vacuo using H3PO4. Evolved CO2 is purified via adsorption/desorption on CaO and is stored prior to counting. The 2.6L proportional counter is surrounded by a gas-flow Geiger anticoincidence guard and 10cm thick Pb shielding to reduce background count rates to ca 4.9 cpm at 1 atm filling and barometric pressures. A barometric sensitivity in background of −0.01cpm/mbar is observed. Constant gas gain is ensured by monitoring the coincidence meson spectrum and normalizing the detector operating voltage. All sample activities are related to the NBS oxalic acid standard count rate which averages 14.71 cpm at 1 atm filling pressure and 15°C. Mass spectrometric assay of CO2 after counting is performed on a VG Micromass 602B instrument to a precision of 0.05% (±1σ). Since uncertainties quoted on all results represent 1σ counting errors alone, they are related to precision of measurement rather than accuracy. The bulk of data quoted here are connected with a long-term study of the medical aspects of artificial 14C from nuclear weapon tests. These results should therefore be assessed in conjunction with those pub previously (Harkness and Walton, 1972; Farmer et al, 1972).

Most of the 14C measurements reported here were made between October 1974 and October 1975. Equipment, measurement, and treatment of samples are the same as reported previously (R, 1968, v 10, p 36-37) except for bone samples (see below).

The Dalhousie University Radiocarbon Dating Laboratory was established in 1972, utilizing equipment and procedures formerly in use at Ohio Wesleyan University, Delaware, Ohio. The laboratory is located on the third floor of the 8-story Life Sciences Center at Dalhousie University. Sample preparation includes leaching with dilute alkali and acid, followed by pyrolysis in a stream of N2 at 500°C. Operating procedures remain essentially the same, utilizing reduction of acid or combustion generated CO2 to the counting gas, methane, over Ruthenium catalyst at 500°C. The flow reactor formerly used has been replaced by an in-line static reactor. Following gas purification and one month product gas storage to permit decay of Radon, samples are counted at 50 to 152cm pressure in either of 2 500ml detectors, or a 2L detector.

This date list includes samples dated from 1968 through 1972. The method of analysis is described in R, 1968, v 10, p 246 and 1970, v 12, p 87. The ages are calculated with the 5568 year half-life without application of any corrections. The NBS oxalic acid standard is used as the modern reference. Errors (± 1 σ) include standard deviations for sample counts, background and modern standard.

This list includes dates measured from January 1974 to June 1975 with previously described CO2 proportional counters (Alessio et al, 1970b). All archaeologic and geologic samples except for Arslantepe series come from Italian territory. Chemical apparatus for CO2 preparation and purification is unchanged (Alessio et al, 1970b). Data recording devices have recently been replaced with integrated circuits built entirely at the Lab. The logic of the circuitry was also modified to provide more stable devices and a higher relative figure of merit A/√B of each counter (A = net activity of modern standard, B = background). Consequently, the resolution of age measurements has increased appreciably. Present values of A/√B for the 4 counters in use are shown in Table 1.

This list contains radiocarbon dates of archaeologic samples of wood, charcoal, and peat measured between 1967 and 1973, analyzed by the Laboratory of the Institute of Archaeology, Leningrad Branch, USSR Academy of Sciences. The samples measured include charcoal from cultural strata and hearths, wood from kurgans and cultural strata, peat, etc, coll from various archaeologic sites by Soviet scientists, as well as a series from Dashly site, Afghanistan.

The first natural 14C measurements in Poland were made, using CO2 + CS2 G M counter as early as 1953 (Mościcki, 1953), but continuous operation was not possible until 1971. Following Poznań Toruń (Mościcki, 1958; 1961) and Gdańsk (Mościcki and Zastawny, 1962a), where the first long series of 14C measurements were made (Mościcki et al, 1967), an actively operating radiocarbon dating laboratory was installed at Gliwice in 1971.

In January 1975 a radiocarbon dating laboratory was established at the Marine Resources Research Institute for geochemical and geologic studies. A liquid scintillation system is employed according to the method of Noakes, Kim, and Akers (1967). A Searle (Nuclear Chicago) Isocap 300 liquid scintillation counter is currently being used for counting. This system is a duplicate of the one formerly used at Texas A & M University except for the counter (Mathews et al, 1972)

The present list includes 35 dates of geologic samples analyzed at the Geobiochemical Laboratory of the Institute of Zoology and Botany, Academy of Sciences, Estonian SSR. Benzene synthesized from wood dating from 1850 ± 10 yr served as a reference standard. All radiocarbon dates have been calculated using 5568 ± 30 yr before ad 1950 as the half-life of 14C.

This list includes most of the samples measured during 1974 and most of those measured previously but not published in the preceding date list (R, 1975, v 17, p 4–34.)

As the Radiocarbon Lab of the Tata Institute, Bombay, has now been shifted to the Physical Research Laboratory (PRL), Ahmedabad, our new date lists will be termed as above and the samples will be given PRL numbers instead of the former TF. All the pending TF samples were given new PRL numbers.

The Radiocarbon Laboratory under the Chair of Nuclear physics of Tbilisi State University is engaged in studies of radiocarbon variation in the atmosphere and mineral waters and determination of the absolute age of archaeologic, geologic, botanical, and other samples. This list reports dates of archaeologic and geologic specimens only. Gas counting and liquid scintillation methods are used for dating.

The radiocarbon dating laboratory of Queens College, CUNY, was established with the joint support of the Research Foundation of the City University of New York and the departments of Anthropology, Biology, Chemistry, and Earth and Environmental Sciences of Queens College. The laboratory has been operational since June, 1975 and is located in the basement of a two-story concrete and brick building.

The following radiocarbon measurements are a partial list of projects and samples dated since the Spring of 1975. The technique used is liquid scintillation counting of wholly synthesized benzene as indicated in R, v 16, p 402-408. The intermediate chemical step of converting CO2 to Li2C2 has been modified so that the CO2 is reacted with the lithium metal at a temperature of 950° to 1000°C instead of the 600°C as formerly done (Tamers, 1975). This modification has had the effect of reducing occasional variable losses in conversion yields in this step, and reducing the reaction time required from 30 min to 10 min for a typical ¼ mole sample. Dates are calculated using a 14C half-life of 5568 yr and errors are reported as one standard deviation. No other correction factors are applied.

The following list of dates is compiled from samples prepared and catalogued since publication of our last date list (R, 1975, v 17, p 99-111). The counting equipment and operating procedures are the same. Ages are quoted with a 1σ counting error which includes statistical variation of the sample count as well as for background and standard, using ad 1950 as the reference year and 95% NBS oxalic acid for 14C dating as the standard. The half-life value used is 5570 years.