scholarly journals La Jolla Natural Radiocarbon Measurements VII

Radiocarbon ◽  
1977 ◽  
Vol 19 (1) ◽  
pp. 19-48 ◽  
Author(s):  
T W Linick
Keyword(s):  
Radiocarbon Dating ◽  
Gas Flow ◽  
Guard Ring ◽  
Low Level ◽  
Center Volume ◽  
La Jolla

Radiocarbon dating of many types of samples has continued at the La Jolla Radiocarbon Laboratory since the last date list was published (Bien and Pandolfi, 1972). Since the 1969 relocation of the laboratory to its present location on Mt Soledad, at least 5 low-level14C systems have generally been in operation. The laboratory has continued to employ acetylene gas proportional counting. Samples were usually measured for 2 to 3 days in each of 2 different detectors. The properties of the 5 counters used in the measurements of samples are as follows (background and net standard counts per minute, respectively, with acetylene of 900mmHg pressure are given in parentheses): 1) Bern counter: Oeschger-type counter-guard ring unit with 1.7L sensitive center volume (2.1, 21.5), 2) MBLE counter: Oeschger-type counter-guard ring unit with 1.6L center volume (1.3, 17.4), 3) 1L counter with separate Q-gas flow guard ring (4.2, 12.9), 4) 0.4L counter with separate guard ring (1.2, 4.2), and 0.1L counter with separate guard ring (0.7, 1.2).

scholarly journals Bern Radiocarbon Dates III

Radiocarbon ◽  
1963 ◽  
Vol 5 ◽  
pp. 305-311 ◽  
Author(s):  
Chr. Gfeller ◽  
H. Oeschger
Keyword(s):  
Radiocarbon Dating ◽  
Radiocarbon Dates ◽  
Low Level ◽  
Physics Department ◽  
University Of Bern

This list covers part of the measurements made at the Radiocarbon Dating Laboratory, Physics Department, University of Bern from summer 1960 until summer 1962. Two low-level counters with incorporated anticoincidence arrangement (Houtermans and Oeschger, 1958) are used for routine C14 measurements.

scholarly journals Quantifying Background Components of Low-Level Gas Proportional Counters

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 420-427 ◽  
Author(s):  
Páll Theodórsson
Keyword(s):  
Radiocarbon Dating ◽  
Low Level ◽  
New Information ◽  
Proportional Counters

I discuss background components of low-level gas proportional counters and show how each component can be estimated based on available data. For more reliable background analysis, further studies are suggested. Based on new information, a generation of low-level gas proportional counting systems for radiocarbon dating may emerge with lower and more predictable background.

scholarly journals Bern Radiocarbon Dates IV

Radiocarbon ◽  
1965 ◽  
Vol 7 ◽  
pp. 1-9 ◽  
Author(s):  
H. Oeschger ◽  
T. Riesen
Keyword(s):  
Radiocarbon Dating ◽  
Radiocarbon Dates ◽  
Ru Catalyst ◽  
Low Level ◽  
Physics Department ◽  
University Of Bern

This list covers part of the samples measured at the Radiocarbon Dating Laboratory, Physics Department, University of Bern since summer 1962. Two low-level counters, as described by Houtermans and Oeschger (1958), with incorporated anticoincidence are used. Each sample is measured in both counters. The CO2 from the sample is converted to methane by pumping a (CO2 + H2)-mixture at a pressure below 1 atm over a Ru-catalyst at 200°C.

scholarly journals Radiometric 14C Dating: New Background Analysis, Basis of Improved Systems

Radiocarbon ◽  
1997 ◽  
Vol 40 (1) ◽  
pp. 157-166
Author(s):  
Pall Theodórsson
Keyword(s):  
Gamma Radiation ◽  
Radiocarbon Dating ◽  
Liquid Scintillation ◽  
General Analysis ◽  
14C Dating ◽  
Low Level ◽  
Its Analysis ◽  
Gamma Detectors

A recent broad study of the background of all types of low-level beta and gamma detectors has now made it possible to analyze its components more reliably and with greater detail. This general analysis is developed further here for gas proportional and liquid scintillation counters used in radiocarbon dating. The background of gas counters, which is dominated by secondary cosmic gamma radiation, is now well understood and can be described quantitatively. The background of liquid counters is less well understood and can only be described semiquantitatively, its analysis resting partly on estimates. Methods to reduce the background of both types of systems are described and their effectiveness discussed. This analysis may help in evaluating the quality of existing systems as well as in designing better ones.

Implications of a European radiocarbon calibration

Antiquity ◽  
1978 ◽  
Vol 52 (206) ◽  
pp. 217-222 ◽  
Author(s):  
J. R. Pilcher ◽  
M. G. L. Baillie
Keyword(s):  
Los Angeles ◽  
Radiocarbon Dating ◽  
Short Term ◽  
Radiocarbon Dates ◽  
Current State ◽  
Calibration Problem ◽  
Dating Method ◽  
La Jolla ◽  
Single Calibration ◽  
Radiocarbon Calibration

Clark (1975) gave a clear account to ANTIQUITY readers of the current state of the radiocarbon calibration problem. It is now 19 years since De Vries demonstrated that one of the primary assumptions of the radiocarbon dating method was in error. Since then more than 1,200 measurements have been made on samples of known-age wood and over 70 papers published on this topic (reviewed by Bermingham and Renfrew, 1972 and by Clark, 1975). In spite of this activity, at the recent radiocarbon conference in Los Angeles and La Jolla no international agreement could be reached on a single calibration or correction that could be used to convert radiocarbon measurements to calendar ages. The problems of calibration have undermined the confidence of many European archaeologists in radiocarbon dating-one hears remarks such as ‘one can’t take the dates seriously, after all they are only radiocarbon dates’. Workers attempting to reconcile calibrated radiocarbon dates with historically based chronologies have found that the agreements do not live up to their expectations based on the quoted standard deviations of the dates. In the short term the results we present here may further convince the archaeologist that radiocarbon dates will not solve his chronological problems. However, we hope to demonstrate that radiocarbon dating is ultimately capable of sufficient accuracy to be fully compatible with historical chronologies

scholarly journals A Counter System for High-Precision 14C Dating

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 399-406 ◽  
Author(s):  
Ede Hertelendi ◽  
Éva Csongor ◽  
Laszlo Zaborszky ◽  
Jozsef Molnar ◽  
Janos Gal ◽  
...  
Keyword(s):  
High Pressure ◽  
High Precision ◽  
Radiocarbon Dating ◽  
Data Evaluation ◽  
14C Dating ◽  
Counting Period ◽  
Low Level ◽  
Electrolytic Copper ◽  
Proportional Counters ◽  
Better Than

A multicounter radiocarbon dating system was developed applying the experiences of the previous one-channel low-level counting facility. The counter system consists of nine electrolytic copper proportional counters of identical diameters with sensitive volumes of 0.35–0.7dm3 and filled with either methane at high pressure (6 bar) or CO2 at 1 bar. The inner counters are surrounded by an anticoincidence shield consisting of five multiwire proportional flat counters filled with propane. The pulses of the detectors are handled by integrated amplifiers, discriminators and anticoincidence units interfaced to a microprocessor-controlled data evaluation unit. Software is written in BASIC using ASSEMBLER sub-routines. The overall precision of the system for modern carbon samples using high-pressure methane-filled counters (B ≍ 0.7 cpm, S ≍ 14 cpm) is better than 4 after a counting period of seven days.

Gas Flow Engineering in Rapid Thermal Processing

1994 ◽  
Vol 342 ◽  
Author(s):  
Z. Nényei ◽  
H. Sommer ◽  
J. Gelpey ◽  
A. Bauer
Keyword(s):  
Low Temperature ◽  
Thermal Processing ◽  
Gas Dynamics ◽  
Silicon Surface ◽  
Gas Flow ◽  
Rapid Thermal Processing ◽  
Inert Gas ◽  
Guard Ring ◽  
Interface Damage ◽  
Bottom Heater

ABSTRACTGas flow engineering involves gas dynamics optimization for effective ambient change before heating and for homogeneous convective cooling of the wafers during the heating steps. Multiple gas buffle system, dynamical gas handling, low pressure operation, low temperature edge guard ring and independent top and bottom heater bank control are the proper tools for this optimization. Silicon surface or interface damage during inert gas anneal can be avoided by addition of a small amount of oxygen.

scholarly journals Radiocarbon Dating in the Arctic Region

Radiocarbon ◽  
1983 ◽  
Vol 25 (2) ◽  
pp. 393-394 ◽  
Author(s):  
Ingrid U Olsson
Keyword(s):  
Volcanic Activity ◽  
Radiocarbon Dating ◽  
Arctic Region ◽  
The Arctic ◽  
Low Level ◽  
Sources Of Error ◽  
Early Results ◽  
Dating Method ◽  
Obvious Source ◽  
The Arctic Region

The Landnám of Iceland is usually dated too early by the 14C dating method, at least to judge from the tradition according to the Landnámabók. Various sources of error are considered. One, the use of driftwood, can be excluded in many cases, since birch is often selected for dating purposes. Second, the settlers may have brought wood with them. A third obvious source of uncertainty is the age of a tree before felling. It is difficult to explain the seemingly too early results by secular global variations of 14C content. A regional low level of 14C may result from volcanic activity or the small size of the land areas in the Arctic region.

Sign in / Sign up

Export Citation Format

Share Document