scholarly journals Dublin Radiocarbon Dates II

Radiocarbon ◽  
1974 ◽  
Vol 16 (1) ◽  
pp. 6-9 ◽  
Author(s):  
P Q Dresser ◽  
I R Mcaulay
Keyword(s):  
Count Rate ◽  
Radiocarbon Dating ◽  
Detection Efficiency ◽  
Scintillation Counter ◽  
Barometric Pressure ◽  
Electronic Equipment ◽  
Background Count ◽  
Background Count Rate ◽  
Radiocarbon Dates ◽  
Silica Cell

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.

scholarly journals Newly Designed 0.8-ML Teflon® Vial for Microvolume Radiocarbon Dating

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 743-747 ◽  
Author(s):  
Michael Buzinny ◽  
Vadim Skripkin
Keyword(s):  
Significant Influence ◽  
Count Rate ◽  
Radiocarbon Dating ◽  
Figure Of Merit ◽  
Liquid Scintillation ◽  
Detection Efficiency ◽  
Operational Parameters ◽  
Counting Period ◽  
Background Count ◽  
Background Count Rate

We have tested two versions of an 0.8-ml volume Teflon® vial, designed specifically for radiocarbon dating in the microvolume range, using a modern Quantulus 1220™ liquid scintillation (LS) spectrometer. We determined the counting performance of each vial type in conjunction with different designs of copper holder, viz., with and without the incorporation of a “Teflon® light coupler”. We also compared the losses of sample benzene during a typical 28-day counting period. Results show that neither vial design nor the type of vial holder used in the intercomparison had a significant influence on counting performance. We recorded an absolute 14C detection efficiency of 82% against a background count rate of 0.1 cpm, i.e., a “figure of merit (FM) value” = 67,240. This compares favorably with the operational parameters anticipated for microvolume 14C dating by modern LS spectrometry. However, variations in the design of the sealing method used between the vial types was reflected in an apparent approximate tenfold difference in the amount of benzene lost during routine counting. In the better case, the evaporation loss was equivalent to 0.032 mg of benzene per day.

scholarly journals Stability of a New, Multichannel, Low-Level Liquid Scintillation Counter System, Kvartett

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 727-736 ◽  
Author(s):  
Sigurđur Einarsson ◽  
Páll Theodórsson
Keyword(s):  
Count Rate ◽  
Liquid Scintillation ◽  
Scintillation Counter ◽  
Counting System ◽  
Background Count ◽  
Background Count Rate ◽  
Low Level ◽  
Quality Control Standard ◽  
Conventional Systems ◽  
Sample Vial

Kvartett is a new liquid scintillation counting (LSC) system for radiocarbon dating that takes a radical departure from conventional systems to obtain a compact, low-level counting system measuring four samples simultaneously. Each sample vial, inside the well of a large NaI(Tl) guard-counter crystal (facing down), sits on top of a vertical PMT. The fourfold counting capacity can be used to increase the number of samples being dated or to get higher precision. The increased throughput helps to keep a rigid quality-control standard. We monitored the background count rate almost continuously for 7 months, and measured the count rate of a standard repeatedly for 2 months. The results show the background and system reproducibility to be stable.

scholarly journals Belfast Radiocarbon Dates II

Radiocarbon ◽  
1970 ◽  
Vol 12 (1) ◽  
pp. 291-297 ◽  
Author(s):  
A. G. Smith ◽  
G. W. Pearson ◽  
J. R. Pilcher
Keyword(s):  
Oxalic Acid ◽  
Count Rate ◽  
Detection Efficiency ◽  
Background Count ◽  
Radiocarbon Dates

The dating equipment in the Palaeoecology Laboratory has remained essentially as described in Belfast I (this volume). Rewiring of the counter has increased the detection efficiency slightly. Background count corrected to 1606 mb is now 11.0 counts/min and the net count rate for 95% of the NBS oxalic acid standard is 56.0 counts/min. All charcoal samples have been pretreated in accordance with the schedule given in Belfast I.

scholarly journals Oak Ridge Associated Universities Radiocarbon Dates II

Radiocarbon ◽  
1968 ◽  
Vol 10 (2) ◽  
pp. 346-349
Author(s):  
John E. Noakes ◽  
S. M. Kim ◽  
F. Fischer
Keyword(s):  
Radiocarbon Dating ◽  
Liquid Scintillation ◽  
Counting Efficiency ◽  
Liquid Scintillation Spectrometer ◽  
Background Count ◽  
Background Count Rate ◽  
Radiocarbon Dates ◽  
Oak Ridge ◽  
Research Activities ◽  
Special Training Program

The Radiocarbon Dating Laboratories of the Oak Ridge Associated Universities (ORAU) has previously published radiocarbon dates under the Oak Ridge Institute of Nuclear Studies (ORINS) name. ORINS has recently changed its name to ORAU and its laboratories and programs have accordingly assumed this new name. The ORINS prefix, which previously designated the published radiocarbon dates of this laboratory, will be continued to minimize confusion in the literature.The radiocarbon dating program carried out at this laboratory is primarily concerned with assisting the ORAU Special Training Program in its teaching and research activities. Radiocarbon dates which appear in this paper represent samples submitted from research groups associated with the 41 universities which make up ORAU and by other college and university personnel who do not have access to radiocarbon dating facilities.Carbon samples are chemically synthesized to liquid benzene and their C14 activity determined by liquid scintillation spectroscopy. Samples are first converted to lithium carbide and then to acetylene gas as described by Barker (1953). The acetylene is catalytically trimerized to benzene by a method described by Noakes et al. (1965). Chemical yields for the synthesized benzene routinely approach 90% with no evidence of chemical impurities or carbon isotope fractionation occurring in the chemistry.A Packard Tricarb Model 314 D.C. liquid scintillation spectrometer, which has been modified for low level counting, is used to count the benzene samples. Counting efficiency is 50% when operating at a voltage of 800 with discriminator setting of 100-800-1000. Background count rate is 1.7 c/m with a 5 cc benzene sample. Shielding consists of 4 in. of lead with coincidence and anticoincidence systems.The modern reference standard is 0.95% activity of NBS oxalic acid standard which is 6.82 c/m/g carbon. Ages are calculated on a C14 half-life of 5570 yr as suggested by Godwin (1962). The statistics quoted are compiled as one standard deviation (1σ) of the uncertainty involved in counting background, standard, and sample.

scholarly journals Texas A & M University Radiocarbon Dates I

Radiocarbon ◽  
1964 ◽  
Vol 6 ◽  
pp. 189-193 ◽  
Author(s):  
John E. Noakes ◽  
J. J. Stipp ◽  
Donald W. Hood
Keyword(s):  
Radiocarbon Dating ◽  
High Energy ◽  
Catalytic Method ◽  
Background Count ◽  
Background Count Rate ◽  
Radiocarbon Dates ◽  
University Of Texas ◽  
Carbon Dating ◽  
Study Programs ◽  
The University

The Radiocarbon Dating Laboratory of Texas A & M University was initiated as a research facility in the Oceanography and Meteorology Department. The facilities are available to graduate study programs and to other research groups associated with the University.Research was begun in June 1960, towards development of a carbon dating method utilizing liquid scintillation counting. Benzene was chosen as the counting solvent because of its high energy transmitting properties and the high carbon content of benzene which could be totally derived from the sample to be dated. A catalytic method of synthesis of C6H6 at low temperature, as first reported by Shapiro and Weiss (1957), was further developed and modified by Noakes and others (1963) to a procedure suitable for carbon dating. A combined effort of this laboratory and the University of Texas Radiocarbon Dating Laboratory has resulted in a routine procedure for carbon dating, as reported earlier (Texas I).In the dates reported here the sample preparation and the method of conversion of carbon samples to the counting solvent, benzene, was the same as reported in the earlier papers cited. The problem, reported then, of variation in background count rate between counting vials was eliminated by prior determination of the background for each vial used. With the exception of samples TAM 1 and TAM 2, all dates reported here were calculated according to this procedure.

scholarly journals Performance of the Packard 2000 CA/LL and 2250 CA/XL Liquid Scintillation Counters for 14C Dating

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 352-358 ◽  
Author(s):  
G T Cook ◽  
D D Harkness ◽  
Robert Anderson
Keyword(s):  
Count Rate ◽  
Liquid Scintillation ◽  
Scintillation Counter ◽  
14C Dating ◽  
Background Count ◽  
Background Count Rate ◽  
Low Level ◽  
On Line ◽  
Guide System ◽  
Careful Manipulation

Results are presented on the comparative characteristics of the Packard 2000 CA/LL liquid scintillation counter with and without the low-level option on line. An initial performance assessment using 14C labeled benzene with butyl-PBD as the scintillant revealed that although the background count rate decreased by approximately a factor of 3 using the low-level option, a substantial decrease in efficiency was also observed. However, subsequent investigations have indicated that, by careful manipulation of both scintillant composition and concentration, this loss in efficiency can largely be overcome with little or no concurrent increase in background count rate. The introduction of an active vial sample holder and a new light-guide system proved to be significant advances on the standard 2000 CA/LL.

scholarly journals Precision Measurements of the Minimum Detectable Activity of Radionuclides by Plastic Scintillators for Radiation Monitoring

2019 ◽  
pp. 3-9
Author(s):  
B. Grynyov ◽  
N. Gurdzhian ◽  
O. Zelenskaya ◽  
V. Lyubynskiy ◽  
N. Molchanova ◽  
...  
Keyword(s):  
Count Rate ◽  
Statistical Processing ◽  
Sensitivity Coefficient ◽  
Minimum Detectable Activity ◽  
National Academy Of Sciences ◽  
Background Count ◽  
Background Count Rate ◽  
Energy Radiation ◽  
Detectable Activity ◽  
Plastic Scintillators

This work is devoted to the precision evaluation of the minimum detectable activity (MDA) measurement of gamma radiation radionuc­lides 137Cs and 60Co using plastic scintillators (PS). Scintillators are part of the detectors, which are sensitive elements of radiation portal moni­tors (PM). PS were produced at the Institute for scintillation materials of the National Academy of Sciences of Ukraine (ISMA NAS of Ukraine). The evaluation was generate in accordance with State standard of Ukraine ISO 5725-2:2005 [1] through statistical processing of experi­mental material. This made it possible to take into account the factors that determine the scattering of results without a model equation. Influence of PS sizes, energy radiation detected and distance from PS to the source of ionizing radiation (SIR) on the value of MDA precision measurement was studied. Precision coefficients of radionuclides MDA measurement evalua­ted when changing PS sizes from 500×300×50 mm (7500 cm3) up to 500×500×50 mm (12500 cm3), changing the energy radiation detected from 662 keV (137Cs) until 1332 keV (60Co), changing the distance from the PS to SIR from 10 to 50 cm. The results are presen­ted in Fig. 6—9 and Table. Found, that the greatest contribution to the increase in MDA precision coefficient measurements makes a change in the irradia­tion geometry. It is shown that when distance from PS to SIR increases from 10 to 50 cm, precision values increase: when registering 137Cs, from 3,9 to 7,0 % (V = 7500 cm3) and from 3,6 to 6,3 % (V = 12500 cm3); when registering 60Co, from 3,1 to 4,3 % (V = 7500 cm3) and from 3,2 to 3,8 % (V = 12500 cm3). It is established, that the obtained results are due to the change in the contribution of background count rate to PS count rate under different measurements conditions. This contribution affects on the value of sensitivity coefficient and consequently on the value of MDA and precision coefficient.

scholarly journals New Data on the Chronology and Development of Cattle Breading During the Eneolithic and Early Bronze Age in the Southern Ural Region

2019 ◽  
pp. 17-36
Author(s):  
Nina Morgunova ◽  
Natalia Roslyakova ◽  
Marianna Kulkova
Keyword(s):  
Bronze Age ◽  
Radiocarbon Dating ◽  
Standard Procedure ◽  
Scintillation Counter ◽  
Ural Region ◽  
Early Bronze Age ◽  
The Southern Urals ◽  
Cattle Breeding ◽  
Radiocarbon Dates ◽  
Southern Ural Region

Introduction. The article considers the features of cattle breeding and consumption of meat products in the Eneolithic cultures (the Samara culture) and the Early Bronze Age cultures (the Repin stage of the Pit Grave culture) on the territory of the Southern Urals (the Samara Trans-Volga region). The paper specifies the chronology of these cultures on the base of radiocarbon dating. The main site for the study was Turganik settlement located in the Southern Ural region (Orenburg region). Methods. More than 800 m2 of the settlement area was excavated. There were six paleosoil layers. Four upper layers were empty, without artifacts. The sixth layer contained Eneolithic finds. The fifth layer contained finds of the Early Bronze Age. The archaeozoological collection was analyzed in accordance with the methodological scheme developed by E.E. Antipina. For radiocarbon dating collagen was treated from bone samples on the base of the standard procedure and radiocarbon activity was measured by Quantulus 1220 low background scintillation counter. Analysis and Results. As a result 32 radiocarbon dates were obtained on animal bones and on organics from pottery of different types from different cultural layers of Turganik settlement. The Eneolithic complex includes ceramics, flint and bone tools. The paper specifies the finds of developed and later stages of the Samara culture. The artifacts of the second stage of the Samara culture were dated to 4900–4500 cal BC. The artifacts of the later stage belong to the period of 4300–3800 cal BC. We suggest that from the Early Eneolithic local people practiced cattle breeding without agriculture. Hunting played a secondary role and fishing was poorly developed. Beef was the main food in the people’s diet during the Eneolithic period. The Early Bronze Age assemblage includes ceramics of the Repin stage of the Pit Grave culture, stone macro-tools, flint arrowheads, items made of bones and copper, slags and scarps of copper ore. The technological analysis supported that ceramics belong to the Pit Grave culture. The layer age is from 3800 to 3300 cal BC. During the Repin stage the role of sheep breeding was increased and consumption of sheep meat prevailed in comparison with the Eneolithic period. This is an evidence of the transition to the nomadic form of stock breeding.

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