bluuebunny/crossref_metadata_2025 huggingface dataset:
Belfast Radiocarbon Dates IV
Authors: Smith A. G. , Pearson G. W. , Pilcher J. R.
Published: July 2016

The dating equipment and operating conditions remain essentially as previously described. All samples in this list have been counted at a filling pressure equivalent to 152 cm Hg at 20°C. The proportional counter has recently been re-wired, resulting in a lowering of the operating voltage. Electron-microscopic examination of the old counter wire showed considerable thickening due to the accumulation of fine dust particles. A filter is being installed in the filling line to minimize this effect. Pretreatments are as given in previous date lists unless otherwise stated.
Patterns of Atmospheric 14C Changes
Authors: Stuiver Minze , Quay Paul D
Published: July 2016

Natural atmospheric 14C changes are caused by fluctuations in upper atmospheric 14C production rates (Q) that are related to earth geomagnetic field variations and changes in solar wind magnetic shielding properties. Climate variability may also be responsible for some of the changes because it influences exchange rates of 14C between the various terrestrial carbon reservoirs.

Upper atmospheric 14C production rates QM, in at/sec cm2 (earth), were calculated for the past 1200 years from the atmospheric 14C record and a carbon reservoir model. The changes in QM are compared in detail with the predicted Q variability derived from an Aa solar modulation mechanism and 20th century neutron flux observations. The influence of earth geomagnetic field changes on the magnitude of the solar wind modulation is discussed, and it is shown that the variations in this magnitude agree with the known differences in earth magnetic field intensity during the past 1200 years. The larger calculated QM oscillations during the sixth millennium bp also agree with this concept.

Solar wind magnetic as well as geomagnetic forces modulate the incoming cosmic ray flux and explain the main features of the atmospheric 14C record. It is argued that climatic fluctuation is not a dominant cause.

The oscillations between 3200 and 3700 BC, as measured by de Jong, Mook, and Becker, differ in rise time from those found for the current millennium.
Natural Radiocarbon Variations from AD 200 to 800
Authors: Bruns Michael , Münnich K O , Becker Bernd
Published: July 2016

High precision radiocarbon measurements (±2.5‰ STD) were carried out on absolutely dated European oak material. These showed that significant short-term atmospheric 14C variations of up to 2 percent occurred between AD 200 and 800. These changes, reflecting a 150-to 180-year periodicity, seem to correlate with the average sunspot activity around that time. In comparison with results obtained by other authors, a very regular pattern of natural atmospheric 14C variations is exhibited.
Experimental and Theoretical Data on Radiocarbon Variation in the Earth's Atmosphere in the Past
Authors: Dergachev V A
Published: July 2016

Some questions in the study of cosmic ray intensity (solar magnetic irregular solar activity, 14CO2, and 14CO in radiocarbon models, etc) on the basis of 14C concentration in the earth's atmosphere are considered.
Large-Volume Liquid Scintillation Counting of Carbon-14
Authors: Eichinger Lorenz , Rauert Werner , Salvamoser Josef , Wolf Manfred
Published: July 2016

Efforts have been undertaken to further improve the relatively simple technique of low-level liquid scintillation counting of 14C. Two different approaches have been made. By synthesizing more benzene for 14C measurement than usual (with up to 19.5g of carbon) an experimental detection limit of about 0.1 percent modern has been achieved (97.5% confidence level, 1000 min). Absorption of CO2 with up to 5.3g of carbon in 160ml of an absorbent-scintillation solution and counting in a special measuring chamber resulted in an experimental detection limit of about 1 percent modern, with the sample preparation taking only 1 hour. The detection limits achieved by the two techniques correspond to 14C ages of about 55,000 and 35,000 years BP, respectively.
Applications of Resonance Ionization Spectroscopy to Ultralow-Level Counting and Mass Spectroscopy
Authors: Kramer S D , Hurst G S , Young J P , Payne M G , Kopp M K , Callcott T A , Arakawa E T , Beekman D W
Published: July 2016

In this paper it is shown that the ability to directly detect a daughter atom, using resonance ionization spectroscopy, in delayed time coincidence with the decay of a parent species promises to drastically reduce the background in low-level counting experiments. In addition, resonance ionization can also be used as an ion source for a mass spectrometer system that is capable of discriminating between isobars.
Radiocarbon Dating of Bone Apatite Using Thermal Release of CO2
Authors: Haas Herbert , Banewicz John
Published: July 2016

Extraction of carbon from bone hydroxy apatite as CO2by heating in an oxygen atmosphere is an alternative method to hydrolysis of the bone. Heating in specific steps allows separation of CO2fractions from different sources, including weakened or sound bone material and secondary deposits. Pretreatments to remove most secondary carbonate and much of the collagen are necessary. Thermogravimetric (weight loss) curves and CO2release patterns during heating show that the temperature interval for collection of the most reliable CO2sample for dating purposes lies between 800 and 950°C. Age dates run on such samples support this conclusion.
Vertical Advection — Diffusion Rates in the Oceanic Thermocline Determined from 14C Distributions
Authors: Quay P D , Stuiver Minze
Published: July 2016

The characteristics of a one-dimensional vertical advection-diffusion ocean mixing model were examined using temperature, salinity, and bomb 14C measurements made during the GEOSECS program. Vertical advection (W) and eddy diffusion (K) rates for the main oceanic thermocline and CO2 gas exchange rates (E) were determined from the depth distributions of salinity and bomb produced 14C measured in the upper 1000m of the Atlantic and Pacific Oceans. In the Atlantic, the results suggest that vertical diffusion rates are lower in the equatorial region (K = 0.6cm2sec—1) than in the temperate region (K = 1.6cm2sec—1). Upwelling rates were calculated for stations located between about 30° N and 30°S and average 10m yr—1, corresponding to an upward transport of about 10 Sverdrups. Model calculations of the gas exchange rate of CO2 indicate a 2 to 3-fold decrease between temperate latitudes and the equatorial latitudes of the Atlantic. For many of the Pacific GEOSECS stations, the Δ14C depth distribution is distinctly different than in the Atlantic, and cannot be used to calculate unique values of K and W that explain both the salinity and 14C depth distributions.
Radiocarbon Evidence for Holocene Recharge of Groundwater, Western Desert, Egypt
Authors: Haynes C Vance , Haas Herbert
Published: July 2016

During Pleistocene pluvial precipitation was sufficient for the maintenance of groundwater supported lakes and for the accumulation of playa lakes in wind-scoured depressions during the early Holocene pluvial. At places where ground water reaches near to the surface, wells (birs) have been dug and maintained in historic times. These birs have been used as sampling sites for water analyses, including carbon-14 levels, carbon and oxygen stable isotope ratios, tritium concentrations, and chemical data.

All the waters from birs analyzed to date produced apparent radiocarbon ages ranging from late historic to early Holocene, and tritium analyses on some of these indicate no recharge during the Atomic age.

Sources of error for the radiocarbon analyses, including exchange with atmospheric CO2, respiration by plant roots, and contact with carbonates of considerably older age, were evaluated. None of these factors have such an extreme impact on the measurements as to render the result invalid. Two trends revealed by these data are an increase in apparent age from northwest to southwest and with subsequent extractions at the same site where the hand-dug well was bailed out and sampled four times within two days.

We conclude that recharge of shallow ground water occurred in early Holocene time, and some recharge of deeper aquifers may have occurred where infiltration paths permitted. Some recharge occurred in late Holocene (post pluvial) time, but the net trend has been toward hyper-aridity that characterizes the area today.
Studies On the Loess Deposits of the Kashmir Valley and 14C Dating
Authors: Kusumgar Sheela , Agrawal D P , Krishnamurthy R V
Published: July 2016

The loessic deposits along with their palaeosols of the Kashmir Valley have been 14C dated using both organic and carbonate fractions. The 14C dates on both the fractions show good concordance. The 14C dates indicate that the last deglaciation in Kashmir (34° N) already started CA 18,000 ± 1000 BP at CA 1600m and CA 15,000 BP at CA 3000m altitude and thus support the recent global evidence of deglaciation having started several millennia before the Holocene.
14C Dating of Recent Crustal Movements in the Persian Gulf and Iranian Makran
Authors: Vita-Finzi Claudio
Published: July 2016

Radiocarbon dating of mollusks and barnacles from fossil shoreline deposits in the Persian Gulf and on the coast of Iranian Makran is being used to assess the extent and rate of recent crustal deformation in the area. Samples are selected with the help of x-ray diffraction and of light and scanning electron microscopy; whenever possible, two or more ages are determined for each locality on monospecific samples. Age/height values have been used to compute local uplift rates by allowing for sea-level fluctuations, but eustatic controversy can be avoided by limiting the analysis to fault chronology and to relative vertical movements between dated sections. Short counting times on large, carefully pretreated samples would supply the numerous, cheap, low-resolution ages required to follow up the preliminary results obtained by the survey.
Radiocarbon Dating with Tandem Electrostatic Accelerators
Authors: Gove H E , Elmore David , Ferraro R D , Beukens R P , Chang K H , Kilius L R , Lee H W , Litherland A E , Purser K H , Rubin Meyer
Published: July 2016

An MP tandem Van de Graaff accelerator at the University of Rochester has been employed since May 1977 to detect 14C in various terrestrial samples. The carbon sample sizes required are 1mg or less. Dating accuracies based on reproducibility now approach (± 80 years). Measurements have been made on 1850 wood, Australian sucrose, a carbon sample from Mt Shasta, a baby woolly mammoth, and an Egyptian bull mummy wrapping.
Direct Detection of 14C At the Harwell Tandem
Authors: Shea J H , Conlon T W , Asher James , Read P M
Published: July 2016

Direct detection of 14C using the Harwell 6MV Tandem accelerator has been achieved using a gaseous ion source. The implications of our results for the use of such sources in this role and for the machine, in general, are discussed.
Use of 39Ar and 14C for Groundwater Dating
Authors: Loosli Heinz Hugo , Oeschger Hans
Published: July 2016

Cosmic-ray produced atmospheric 39Ar activity (T1/2 = 269 yr) has been determined at 0.11 ±0.012 dpm/lt argon. Ice samples from two profiles in Greenland bore holes showed conclusively that 39Ar dating leads to correct ages. Corrections can be made for possible contamination of the samples with ambient air during field extraction and during laboratory processing by measuring 85Kr in the same samples.

The following isotopes: 14C, 39Ar, 85Kr, 3H, partly 32Si, 13C, and 18O were investigated in 20 groundwater samples. Unexpectedly large discrepancies between “14C ages” and “39Ar ages” were observed for many of these samples. For example, a horizontal profile of a confined sandstone aquifer in the Franconian Albvorland showed decreasing 39Ar and 14C activities from respectively, 100 percent to 17 percent and 80 percent to 0.3 percent of modern activity, corresponding to elapsed time periods of 700 and >20,000 years, respectively.

It seems unlikely that gas exchange through the aquiclude is the cause of this discrepancy. It can neither be explained by only assuming that the water represents a mixing of components with different ages. We detected the possibility of underground production of 39Ar in thermal spring water from Zurzach, Switzerland. Its argon showed higher specific activity than atmospheric argon. Elsewhere, however, samples were found containing no detectable 39Ar activity: two wells of a confined carstic aquifer in Ingolstadt, Germany, show less than 7 percent atmospheric activity.

In our opinion, the assumptions on which the 14C method in hydrology are based need to be critically re-examined. It is possible that for some aquifers carbonate exchange between solid and liquid phases in the aquifer changes 14C results to a larger degree than generally assumed.
Paleoclimatic Evidence in Apparent 14C Ages of Saharian Groundwaters
Authors: Sonntag Christian , Thorweihe Ulf , Rudolph Jochen , Löhnert E P , Junghans Christel , Münnich K O , Klitzsch Eberhard , Shazly E M El , Swailem F M
Published: July 2016

Frequency distributions of more than 300 14C groundwater ages from various regions in northern and southern Sahara reflect the alternating sequence of humid and arid periods in the Sahara during the Holocene and late Pleistocene. A broad frequency maximum between 20,000 and 50,000 years bp indicates a long humid period. During this time span, the northern Sahara received rain from the Western Drift, which is concluded from a west-east decrease of deuterium and oxygen 18 of these groundwaters (continental effect). In the time-slice between 14,000 and 20,000 years bp, groundwater formation was significantly lower due to a cool and (semi-)arid period. In the Holocene, the Saharian climate is characterized by a sequence of dry and wet periods.
Search for Pedogenic Phases During the Younger Pleistocene and Holocene (Soltanien and Rharbien) of Tunisia
Authors: Scharpenseel H W , Zakosek Heinrich , Neue Ulrich , Schiffmann Heinrich
Published: July 2016

Radiocarbon dates, obtained from paleosols, sediments, fossils, and groundwater samples of North Africa and especially, Tunisia, were investigated for information on phases of pedogenesis throughout the younger Pleistocene and Holocene in north and central Tunisia. This paper evaluates available data, while a larger set of new samples is under study, which, hopefully will exhaust the problem and will reveal whether extrapolations such as those made in this paper, eg, phases of pedogenesis from groundwater data, are correct.

Frequency distribution of the dates from groundwaters taken by systematic sampling, as well as from random soil samples from open pits that yielded access to buried paleosols, indicate that organic matter was being produced for 7 or 8 periods. The evidence suggests major pedogenic activity at about 2000 BP, 4000 to 6000 BP, 8000 to 12,000 BP, and perhaps 21,000 to 25,000 BP.
The First 20 Years of Radiocarbon Dating: An Annotated Bibliography, 1948-68; A Pilot Study
Authors: Polach Dilette
Published: July 2016

A bibliography of the radiocarbon dating literature for the years 1948-68, which is in the process of compilation, is examined and a format is proposed. A survey of literature growth has also been undertaken. This enables projections of the numbers of publications referring to radiocarbon dating to be made. The estimated number of publications for the year 1978 is compared to literature retrieval obtained by interrogating eight relevant computer data bases. It is concluded that computer information retrieval is not satisfactory. Bibliographic control of radiocarbon dating literature would be best achieved by a bibliography dedicated to the subject and updated at regular intervals.
National Physical Laboratory Radiocarbon Measurements II
Authors: Callow W. J. , Baker M. J. , Pritchard Daphne H.
Published: July 2016

The following list comprises measurements made since those reported in NPL I and is complete to the end of November 1963.

Ages are relative to a.d. 1950 and are calculated using a half-life of 5568 yr. The measurements have been corrected for fractionation and referred to 0.950 times the activity of the NBS oxalic acid as a contemporary reference standard. The quoted uncertainty is one standard deviation derived from a proper combination of the parameter variances, viz. those of the standard and background measurements over a rolling twenty-week period, of the sample measurements from at least three independent fillings, of the δC13 measurements and of the de Vries effect (assumed to add an additional uncertainty equivalent to a standard deviation of 80 yr). Any uncertainty in the half-life has been excluded so that relative C14 ages may be correctly compared. Absolute age assessments, however, should be made using the accepted best value for the half-life and the appropriate uncertainty included. If the net sample activity is less than 4 times the standard error of the difference between the sample and background activities, a lower limit to the age is reported equivalent to a sample activity of 4 times the standard error of this difference.

The description of each sample is based on information provided by the person submitting the sample to the Laboratory.

The work reported forms part of the research programme of the Laboratory and is published by permission of the Director.
U. S. Geological Survey Radiocarbon Dates VII
Authors: Ives Patricia C. , Levin Betsy , Robinson Richard D. , Rubin Meyer
Published: July 2016

This date list contains the results of measurements made during 1961, 1962 and 1963. The method of counting, utilizing acetylene gas, remains essentially unchanged, except for the addition of some solid state electronics. The method of computation, using the Libby half-life of 5568 ± 30 yr, is continued. The error listed is always larger than the one-sigma statistical counting error commonly used, and takes into account known uncertainty laboratory factors, and does not include external (field or atmospheric) variations.

Unless otherwise stated, collectors of all samples are members of the U. S. Geological Survey.
Arizona Radiocarbon Dates V
Authors: Damon Paul E. , Haynes C. Vance , Long Austin
Published: July 2016

With few exceptions the C14measurements reported here were made in this laboratory between October 1, 1962 and November 1, 1963.
Smithsonian Institution Radiocarbon Measurements I
Authors: Sigalove Joel J. , Long Austin
Published: July 2016

The radiocarbon dating laboratory at the Smithsonian Institution, Division of Radiation and Organisms, was established in September 1962. After careful calibration with known samples and refinements in the methane synthesis system, routine analysis of samples was begun in the spring of 1963.
Uppsala Natural Radiocarbon Measurements IV
Authors: Olsson Ingrid U. , Kilicci Serap
Published: July 2016

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.
Birmingham University Radiocarbon Dates II
Authors: Shotton F. W. , Blundell D. J. , Williams R. E. G.
Published: July 2016

Measurements have continued with the 6 L counter which has proved reliable at pressures as high as 2.6 atm and as low as 0.3 atm. It has now been enclosed in a double ring of 27 geiger tubes which has reduced the background count to 10 cpm at 2 atm. So far, we have had no success with the 1.5 L Oeschger-type proportional counter. Failure to obtain steady readings is probably due to continued outgassing from the teflon insulation. All insulating parts have now been remanufactured from the same source of teflon as was used in the 6 L counter, and the Oeschger counter is being reassembled.

Results are still given without correction for δC13. Errors quoted refer only to the standard deviation calculated from a statistical analysis of count rates and the Libby half-life of 5570 ± 30 yr.
Riken Natural Radiocarbon Measurements IV
Authors: Yamasaki Fumio , Hamada Tatsuji , Fujiyama Chikako
Published: July 2016

The C14 dates given below are a continuation of the work presented in our previous list (RIKEN III), and have been obtained by counting CO2 at ca. 2 atm pressure in a 2.7 L stainless steel counter. Results obtained mainly during 1967 are described.

Shell samples were treated with 1% HCl to remove the outer 10%. Calcareous deposits on the surface, when observed, were removed by mechanical means.

Dates were calculated on the basis of the C14 half-life of 5568 yr and 95% NBS oxalic acid as modern standard. No correction was applied even for fresh water shell samples.
University of Rome Carbon-14 Dates VI
Authors: Alessio M. , Bella F. , Cortesi C. , Graziadei B.
Published: July 2016

The list includes age measurements carried out from December 1966 and November 1967. All samples both of archaeologic and geologic interest are drawn from Italian territory.

Chemical techniques have remained unchanged (Bella and Cortesi, 1960). Two counters have been used for dating: the 1st, of 1.5 L, already described (Bella and Cortesi, 1960; Alessio, Bella, and Cortesi, 1964), the 2nd, of 1 L, recently assembled, is identical to the previous 1 L counter (Alessio, Bella, and Cortesi, 1964), its anticoincidence system was realized by a plastic scintillator and photomultipliers. Background 6.15 ± 0.08 counts/min, counting rate for modern carbon 24.49 ±0.15 counts/min. Higher efficiency of electronic recording was obtained by reducing pulse length and by a few other changes. All samples are usually measured by both counters.

The errors quoted, as in previous measurements, are 1σ statistical error. Age has been calculated using Libby's half-life of 5568 ± 30 yr, with 1950 as the standard year of reference. As in all previous measurements, the same modern wood, grown near Rome between 1949 and 1953, has been taken as modern standard: its activity has once again been carefully checked and judged satisfactory.
Tartu Radiocarbon Dates III
Authors: Punning J. M. , Liiva A. , Ilves E.
Published: July 2016

In dating the samples reported here as well as in calculating their ages, the same equipment and method of processing and counting were used which were previously described in Tartu I and II.
All-Union Geological Institute Radiocarbon Dates I
Authors: Arslanov Kh. A. , Gromova L. I. , Rudneyev Yu. A.
Published: July 2016

For determining age scintillation variant was used. Measurement of a large quantity of benzol [benzene] permitted reaching a limit of 62,000 yr without isotope enrichment. Precautions against contamination of the samples with contemporary carbon and tritium were taken in laboratory handling. Dating began only after it had been established that contamination had not taken place during chemical treatment. Benzol which displayed no radioactivity was synthesized from anthracite. Special measures were taken to remove humic acids from the sample by boiling the powdered sample for three days with three fresh lots of 2% solution of NaOH (Arslanov et al., 1966a, p. 134).
Radiocarbon Dating in the Vernadsky Institute V
Authors: Vinogradov A. P. , Devirts A. L. , Dobkina E. I. , Markova N. G.
Published: July 2016

Charcoal from layer of buried soil from old brick works in Mende, Hungary (47° 30′ N Lat, 19° 30′ E Long) [unconfirmed, D.B.S.]. Deposits are humic loess loams, containing bits of charcoal. Sample at depth ca. 6.5 m. This cross section is one of classical loess excavations in Hungary. Sample coll. 1964, by M. Pechi [Pees] and D. Khan [Hahn].
Gakushuin Natural Radiocarbon Measurements VII
Authors: Kigoshi Kunihiko , Aizawa Hiroko , Suzuki Nobuko
Published: July 2016

This list continues Gakushuin VI (Radiocarbon, 1967, v. 9, p. 43-62), the same instruments and techniques having been employed.

Age calculations are based on the Libby half-life of C14, 5570 ± 30 years, and the modern activity given by 0.95 Aox, i.e., 95% of the activity of NBS oxalic acid standard. The errors quoted are the standard deviation obtained from the number of counts only. When observed activity is less than 2σ above background, infinite date is given with a limit corresponding to the activity of 3σ, and when it is greater than 0.95 Aox −2σ, modern date is given with a limit = 0.95 Aox —3σ. For shell samples, dates are computed without any correction for environmental and biological isotopic fractionation.

The description and comments are essentially those of the submitters.
Gif Natural Radiocarbon Measurements IV
Authors: Delibrias G. , Nakhla S. M. , Labeyrie J.
Published: July 2016

This list reports certain measurements made from 1965 to 1967. These samples are devoted to a special study of organic matter in soils. The work in large part is the subject of a thesis defended in Paris by S. M. Nakhla, 1968.
Isotopic Fractionation in Corn
Authors: Lowdon J. A.
Published: July 2016

This study was started during the summer of 1965 because of the discrepancy observed between dates obtained from wood charcoal and charred corn samples collected from the same archaeologic sites. These results are listed in Table 1.
Illinois State Geological Survey Radiocarbon Dates I
Authors: Kim Stephen M. , Ruch R. R.
Published: July 2016

The radiocarbon dating laboratory of the Illinois State Geological Survey has been established to satisfy a growing need for radiocarbon dates for an active Pleistocene research program. Because of the age and type of material dated, the benzene liquid scintillation counting method is employed in this laboratory. The detailed chemical procedure for converting carbon to benzene has been published by Noakes, Kim, and Stipp (1965) and Noakes, Kim, and Akers (1967); however, the procedures for benzene synthesis and sample counting are briefly explained below to clarify this laboratory's procedure.

An organic sample, such as peat, organic silt, or wood, is burned and the CO2 evolved is absorbed in NH4OH. SrCl2 solution is added to precipitate the carbonate, and the solution plus precipitate is boiled and cooled before filtration of SrCO3. The SrCO3 is acidified with dilute H3PO4 to liberate CO2 in a closed system, and the CO2 is converted to C2H2, as reported by Barker (1953). In this method, 2.4 gm of dry packed lithium, obtainable from the Lithium Corporation of America, is used for each liter of CO2 that is converted to C2H2. Trimerization of the C2H2 to form C6H6 is accomplished using a vanadium-alumina catalyst.

To the C6H6 synthesized from the sample carbon, 2 cc of toluene containing 100 mg Butyl-PBD, 2-(4-tert-Butylphenyl)-5-(4-Biphenylyl)-1,3,4-Oxadiazole, are added, and this mixture is made to a total volume of 10 cc with spectrograde C6H6. A modified Packard Instrument Co. liquid scintillation spectrometer (Model 3375) is used for measurement of C14 activity.

Ages are calculated from a C14 half-life of 5568 years, and the standard deviation (1σ) is based only on counting errors; however, if calculated error is less than 200 years, 200 years is chosen as one standard deviation (1σ).
University of Kiel Radiocarbon Measurements IV
Authors: Willkomm H. , Erlenkeuser H.
Published: July 2016

The following dates are samples measured since publication of Kiel III (Radiocarbon, v. 10, p. 328–332). Age calculations are based on 95% of the activity of NBS oxalic-acid standard as modern value of A.D. 1950. Results are calculated with Libby half-life and reported in yr before 1950. Error corresponds to 1σ variation of sample net counting rate as well as modern standard and background, but does not include the uncertainty in C14 half-life and in secular C14 variations. Dates are not corrected for isotopic fractionation.
University of Rome Carbon-14 Dates VII
Authors: Alessio M. , Bella F. , Cortesi C. , Turi B.
Published: July 2016

We list measurements carried out between June and November 1968. Archaeologic samples are from Italian and Swat (W Pakistan) territories; all geologic samples are from Italian territory.

Chemical preparation of samples, measurement technique, and the modern standard are unchanged (Bella and Cortesi, 1960; Alessio, Bella, and Cortesi, 1964; Alessio et al., 1968).

For each sample of CO2 the counting rate was corrected according to mass-spectrometrically measured C13/C12 ratio. Isotopic analyses were carried out with a 6 in., 60°-sector, double-collecting mass spectrometer, designed and built by G. Boato at Ist. di Fisica, Univ. of Genoa (Boato et al., 1960) and now in use at Ist. di Geochim., Univ. of Rome. C13/C12 ratio is reported as δ-value, the deviation in parts per mil of the C13/C12 ratio of sample from the PDB standard:
Tata Institute Radiocarbon Date List VII
Authors: Agrawal D. P. , Gupta S. K. , Kusumgar Sheela
Published: July 2016

We continue to give dates based on the half-life of 5568 years according to the decision of the Sixth Pullman Conference (Internatl. Conf., Pullman, 1965). The year 1950 has been used as a reference year for converting the dates to A.D./B.C. scale. A value corresponding to 95% net counting rate of the NBS oxalic acid has been used as the modern reference standard.
Yale Natural Radiocarbon Measurements IX
Authors: Stuiver Minze
Published: July 2016

The present list represents a major portion of the samples measured since publication of the last date list in 1963. As in previous lists, dates are reported in terms of the 5568 yr half-life. Infinite dates are reported as beyond a limit equal to 2σ above background. Nearly all of the samples were measured in one of three quartz counters with backgrounds of 0.7 to 1.2 cpm per liter of effective counting volume at working pressures of about two atmospheres. The age errors quoted are based only on the standard deviations in counting rates of sample and standards.

The various C14 projects of the Radiocarbon Laboratory have been supported by the National Science Foundation, Grants GP 4879 and GA 1157; the tree ring research has been supported by the Atomic Energy Commission under contract AT (30-1) 2652. Technical assistance has been provided by Carolyn H. Morgan and Terry C. Eisensmith.
La Jolla Natural Radiocarbon Measurements IX
Authors: Linick T W
Published: July 2016

The following date list covers samples dated by the La Jolla Radiocarbon Laboratory during calendar year 1978. All archaeologic, all geologic, and some geochemical and botanical samples measured during that period are included here. Recent measurements of 14C in tree rings and in annual coral rings will be published elsewhere. Plots and discussion of data for corals from Belize and Florida have been published already by Druffel (1980).
Queens College Radiocarbon Measurements III
Authors: Pardi Richard , Newman E R
Published: July 2016

This list contains analyses completed between January, 1976 and April, 1977. Details of laboratory operation are contained in our first list (R, 1975, v 18, p 205). Samples submitted for analysis are reviewed by a committee consisting of W DeBoer, E Hansen, Anthropology; L Marcus, Biology; W S Newman, D L Thurber, Earth and Environmental Sciences; and Richard Pardi, Radiocarbon Laboratory.
University of Texas at Austin Radiocarbon Dates XIV
Authors: Valastro S , Davis E Mott , Varela Alejandra G , Ekland-Olson Carolyn
Published: July 2016

This list reports certain 14C measurements completed by December 1979; other projects completed by this time will be reported later. Age calculations are based on 14C half-life of 5568 yr and modern standard of 95% NBS oxalic acid, supplemented by tree rings of pre-industrial wood from a log cut in the 1850's (Tx-540; R, 1970, v 12, p 249). Deviations reported are based on counting statistics of sample, background and modern, and are ± 1σ, except that when sample count approaches either modern or background, 2σ limits are reported. Unless noted, 12C/13C measurements were not made and results are not corrected for 13C fractionation (assumed ratio = −25‰ WRT PDB). Our laboratory uses liquid scintillation counting of benzene, with Li2C2 and vanadium-activated catalyst in preparation; chemical yields range between 95% and 99%. Three counters are employed; a Packard Tri-Carb Model 3002 and 2 Beckman LS230 spectrometers obtained through a grant from the National Science Foundation.
AMS Radiocarbon Dating of Bones at Arizona
Authors: Long Austin , Wilson A T , Ernst R D , Gore B H , Hare P E
Published: July 2016

Modern bone contains ca 25% protein material, most of which is collagen. Amino acids separated from collagen isolated from bone are suitable for 14C dating of fossil bone, but attempts to carry out this procedure on bones seriously depleted in protein can yield erroneous 14C dates. Amino-acid analysis of fossil bone gives quantitative information on the degree of preservation of its organic component. Also, the relative abundance of the amino-acid components reveal the degree to which the collagen-like pattern has been altered. Alteration may be caused by addition of extraneous material. A 1mg sample of bone material is sufficient for this preliminary analysis. We have developed a series of acceptance criteria for whether a particular specimen is likely to yield the correct 14C age. 14C dating of fossil bones not seriously depleted in protein is a straightforward procedure and yields reliable dates.
Benzene Purity in Radiocarbon Dating Samples
Authors: Switsur Roy , Waterhouse John S
Published: July 2016

Gas chromatographic analysis of the benzene obtained for radiocarbon dating revealed only very low levels (<200 ppm in total) of impurities, most of which were alkylbenzenes. Traces of acetone and phenol were also found. These impurities, at such low levels are thought unlikely to affect counting efficiency.
Examination of Freshwater Peat Pretreatment Methodology
Authors: Williams John B
Published: July 2016

Preparation techniques used in dating freshwater peat were evaluated and compared using a homogeneous sample. This paper details various approaches to pretreatment of this material and presents the resultant 14C dates. General trends in the results are discussed.
14C Dating with the Gif-sur-Yvette Tandetron Accelerator: Status Report and Study of Isotopic Fractionation in the Sputter Ion Source
Authors: Arnold Maurice , Bard Edouard , Maurice Pierre , Valladas Helene , Duplessy J C
Published: July 2016

The standard procedure for measuring 14C at the Gif-sur-Yvette Tandetron AMS facility is described. A new sample manipulator and automated measurements are being used and have been operational for six months. Evidence of isotopic fractionation in the sputter ion source is provided. We take this into account by measuring the 13C/12C ratio of the sample in the accelerator.
Radiocarbon Dating With the Quantulus in an Underground Counting Laboratory: Performance and Background Sources
Authors: Kalin Robert M , Long Austin
Published: July 2016

The University of Arizona Radiocarbon Laboratory purchased a state-of-the-art LKB Quantulus LSC and placed it into a new underground counting chamber. We have investigated the performance of the Quantulus in this setting comparing different vial types, checking background sources and experimenting with sample size.
A Beta Test Comparison Between the New Packard 2260 XL and the LKB Quantulus and 1219 SM: Low-Level Radiocarbon and Tritium Determinations
Authors: Kalin Robert M
Published: July 2016

A Packard 2260 XL liquid scintillation counter was placed in an underground counting chamber to test performance under immense physical shielding. Results from the Packard 2260 XL are compared with two other counters under the same conditions, the LKB Quantulus, which has operated for two years in this laboratory, and the LKB 1219 SM, in use since January 1988.
Optimization of Liquid Scintillation Counting Conditions With Two Kinds of Vials and Detector Shields for Low-Activity Radiocarbon Measurements
Authors: Rauret Gemma , Mestres J S , Garcia J F
Published: July 2016

Low-level radiocarbon measurements were made using two liquid scintillation (LS) counters, both with passive lead shields of approximately the same dimensions. The first one had a conventional background reduction with low-activity lead and “high-low” coincidence bias selection, and the second one had a spectrum analysis background reduction based on the different three-dimensional pulse-height signal of background and beta pulses.

The performance of commercial teflon-copper and glass vials were compared with both LS counters. Optimum counting conditions for the two detectors studied were also established. From results obtained, quality parameters and characteristics of quench curves were studied. Performances of each counter in the working conditions established were also compared.
A 36Cl Profile in Greenland Ice from AD 1265 to 1865
Authors: Conard N J , Kubik P W , Gove H E , Elmore David
Published: July 2016

We have measured the concentration of 36Cl in 67 samples from the upper portion of the Camp Century ice core. The profile extends from AD 1265 to 1865 and covers the times of the Wolf (AD 1282–1342), Spoerer (AD 1416–1534) and Maunder (AD 1645–1715) minima in sunspot number. Although the profile exhibits much short-term variation, a smoothed plot of the data shows a strong peak in 36Cl concentration over the time of the Maunder Minimum. The deeper part of the core suggests increased deposition of 36Cl over the periods of the Wolf and Spoerer minima. The time resolution of the profile is inadequate for testing for an 11-year periodicity in our data. The data augment evidence from 10Be and 14C studies which indicate solar modulation of radioisotope production. Since, however, much of the short-term variation of 36Cl seems to be independent of solar activity, other factors must affect the deposition of 36Cl in ice. These variations could be due in part to mechanisms affecting the transport of 36Cl in the atmosphere. Based on our data from Camp Century, we calculate an average input of 36Cl of 24 atoms/m2 sec.
Ultra-Small Carbon Samples and the Dating of Sediments
Authors: Vogel J S , Briskin Madeleine , Nelson D E , Southon J R
Published: July 2016

Radiocarbon dates from sediment core samples are usually obtained on the whole organic carbon portion in order to use as little of the valuable sediment as possible. Such measurements may not result in an accurate chronology of the sediment because the material may include carbon from different reservoirs at the time of deposition. The development of AMS techniques for dating ultra-small (20–500μg) carbon samples permits dating various components of cored sediments. We give examples of physical and chemical fractions of sediments which illustrate the large differences in ages obtainable from materials at the same sediment depth. The dating of all or several of these fractions demands more complex interpretations than just the derivation of a sedimentation rate from whole organic carbon dates.
Shifts in 14C Patterns of Soil Profiles Due to Bomb Carbon, Including Effects of Morphogenetic and Turbation Processes
Authors: Scharpenseel Hans-Wilhelm , Becker-Heidmann Peter
Published: July 2016

Principles contributing to changes and the final balance of rejuvenation in 14C dates of soil profiles are identified. The annual addition to the atmosphere of ca 5.5·1012kg of dead carbon from fossil carbon sources and 1.5·1012kg of older carbon from forest clearing make soil appear older. Bomb carbon and annual recycling of most of the 115·1012kg of terrestrial organic carbon, equivalent to the annual photosynthetic turnover of carbon, rejuvenates soil dates. This also applies to root growth, animal transport, and in acid or alkaline soils, to humus percolation. All available 14C dates of soil profiles were evaluated for the impact of bomb carbon. We also studied the effects of morphogenetic soil-forming processes, such as turbations, on soil rejuvenation. Bioturbation, as a general principle of soil dynamics, requires more differential treatment due to modern and bomb carbon that constitutes body carbon of earthworms as well as steadily increasing 14C age with depth in all Mollisols.
14C in the Environment of Swiss Nuclear Installations
Authors: Loosli Heinz Hugo , Oeschger Hans
Published: July 2016

The results of a 10-year survey of 14C content in tree leaves from the vicinity of Swiss nuclear installations are reported. The interpretation is based on the results from a reference station showing a systematic decrease from δ14C = +350 in 1977 to ca 4–190 in 1987. Excess activities of up to ca 100 are observed in the vicinity of nuclear power plants which are compatible with release rates and dilution calculations. A higher excess of up to 1400 is measured in the close vicinity of a small research plant which releases the activity on top of the roof. The determined decrease of the activity with distance can be described by a power law with ca −1.4 in the exponent. Additional doses of 14C to plants and population from excess 14C activities are estimated to be negligible compared to natural doses.
14C Release in Various Chemical Forms With Gaseous Effluents From the Paks Nuclear Power Plant
Authors: Hertelendi Ede , Uchrin György , Ormai Peter
Published: July 2016

We present results of airborne 14C emission measurements from the Paks PWR nuclear power plant. Long-term release of 14C in the form of carbon dioxide or carbon monoxide and hydrocarbons were simultaneously measured. The results of internal gas-proportional and liquid scintillation counting agree well with theoretical assessments of 14C releases from pressurized water reactors. The mean value of the 14C concentration in discharged air is 130Bqm-3 and the normalized release is equal to 740GBq/GWe · yr. > 95% of 14C released is in the form of hydrocarbons, ca 4% is apportioned to CO2, and <1% to CO. Tree-ring measurements were also made and indicated a minute increase of 14C content in the vicinity of the nuclear power plant.
A Comparison of Methods Used for the Calibration of Radiocarbon Dates
Authors: Aitchison T C , Leese Morven , Michczynska D J , Mook W G , Otlet R L , Ottaway B S , Pazdur M F , Van Der Plicht J , Reimer P J , Robinson S W , Scott E M , Stuiver Minze , Weninger Bernhard
Published: July 2016

Current calibration methods for single and replicate 14C dates are compared. Various forms of tabular and graphic output are discussed. Results from all the methods show reasonable agreement but further methodological development and improvements in computer output are required. Comparison of existing techniques for a series of non-contemporaneous dates showed less agreement amongst participants on this issue. We recommend that calibrated dates should be presented as a combination of graphs and ranges, in preference to mean and standard deviation.
Environmental Isotope Study (14C, 13C, 18O, D, Noble Gases) on Deep Groundwater Circulation Systems in Hungary With Reference to Paleoclimate
Authors: Stute Martin , Deak Jozsef
Published: July 2016

We have studied environmental isotopes and noble gases in groundwater samples from various locations in the Great Hungarian Plain along two selected hydrogeological cross-sections of ca 100km. The 14C groundwater ages were corrected hydrochemically and compared with age information derived from excess helium due to 4He from α-decay of U and Th and their daughter nuclides within the aquifer and to He accumulation from the crustal (and mantle) He flux. In correcting the 14C groundwater ages, we considered carbonate dissolution under open and closed system conditions in the infiltration areas. Non-radioactive reduction of the 14C/12C isotope ratio also plays an important role due to the addition of “dead” carbon species to groundwater along its subsurface pathway. High (corrected) 14C ages, which fall into the last global cold period, are supported by significantly lower heavy stable isotope values as well as lower temperatures derived from the noble gases Ne, Ar, Kr and Xe.
14C Analyses of Groundwater From the Botucatu Aquifer System in Brazil
Authors: Aurelia Annkarin , Silva Kimmelmann E , da Cunha Rebouças Aldo , Marlucia Maria , Santiago Freitas
Published: July 2016

Measurements of 14C activity as well as determinations of the stable isotope composition (18O, 2H and 13C) of groundwater samples were made to investigate the flow path, origin, recharge and age of the Botucatu Aquifer System in Brazil, between 1984 and 1987. The stable oxygen isotope composition reflects infiltration during several climatic recharge conditions. Measured 14C activities range from 0.4 to 94.2% modern. δ13C values enable us to distinguish two groundwater types of different origins. There is a gradual increase of 14C ages from the outcrop area towards the central part of the basin, associated with a progression of the confining conditions. Anomalous fluoride contents seem to be correlated with high 14C ages of the groundwater. The reliability of the 14C data is discussed.
Progress in Radiocarbon Dating the Shroud of Turin
Authors: Gove H E
Published: July 2016

An account is presented of the current status of the project to radiocarbon date the cloth of the shroud of Turin. The procedures dictated by the Turin ecclesiastical authorities to accomplish this are discussed. It will be concluded that the original protocol, as agreed to by all parties at the Turin Workshop in 1986, suggested a preferable procedure. However, if the three laboratories, who accepted the task of dating the shroud, obtain the same age for the shroud and the three control samples within a standard deviation or two completely independently, most knowledgeable scientists will probably accept the results.
The Need for a Calibrated Radiocarbon Chronology of Near Eastern Archaeology
Authors: Bruins H J , Mook W G
Published: July 2016

Progress in radiocarbon dating and calibration accuracy should lead to the development of a calibrated radiocarbon chronology of Near Eastern archaeology, particulary for historical times. The lack of such an independent and impartial chronology is a major constraint, not only in archaeological studies, but also for interdisciplinary research involving the history of man, landscape and climate in the Near East and adjacent regions.
The Radiocarbon Data Base of Japan
Authors: Omoto Kunio
Published: July 2016

About ten radiocarbon laboratories operate in Japan and have dated more than 25,000 samples since 1960. Geomorphic development and human activities since the last glaciation have been documented with radiocarbon determinations. In order to apply these dates more effectively, the author finds it necessary to create and maintain a radiocarbon database system, which he has been doing since 1985, using a personal computer system linked to a telephone line. A researcher may access, search and retrieve data from the Radiocarbon Database System of Japan.