1,721,016 research outputs found
The influence of injection parameters on mass fractionation phenomena in radiocarbon analysis
No full textThree different possible sources of mass fractionation have been investigated in an accelerator mass spectrometer
system using sequential injection, namely: the influence of the accelerating/decelerating gaps in front of- and after the
bouncing magnet, the influence of changes in the ion trajectories for the three carbon isotopes during bouncing and
finally the influence of beam intensity. Measurements have indicated that the first two of these sources on the isotopic
ratios measurements can be neglected. On the other hand, it was demonstrated that increasing beam intensity influences
the 14C/12C ratio and to a lesser extent the 14C/13C ratio. This is probably related to space charge effects
Radiocarbon dating by accelerator mass spectrometry: fundamentals and applications to archaeology
No full textHigh resolution radiocarbon dating of prehistoric sites in southern Italy
No full textA new facility for accelerator mass spectrometry radiocarbon
dating has been put in operation at the University of
Lecce in southern Italy. The general features of the facility are
described, showing how by the use of electrostatic andmagnetic
analyzers the radiocarbon content in several kinds of sample
materials can be measured. The performances of the system are
also given in terms of precision, accuracy and background. The
results of the radiocarbon dating of two prehistoric sites are also
reported
Study of the formation of biogenic speleothems found in submarine caves at the cape of Otranto, Italy, by 14C AMS
No full textSubmarine caves at the Cape of Otranto, Italy, contain eccentric stalactites that were recently identified as entirely biogenic. One of these stalactites was sectioned along its longitudinal axis in order to select samples for radiocarbon dating. 14C AMS measurements provided fundamental information for the interpretation of the biogenic process and revealed that the formation of the pseudostalactites continued for approximately 5000 years with a decrease in the longitudinal growth rate over time. Measurements of modern organisms were performed to assess the accuracy of the radiocarbon determination, calibrated in calendar years by measuring the local marine reservoir age
Bringing AMS radiocarbon into the Anthropocene: Potential and drawbacks in the determination of the bio-fraction in industrial emissions and in carbon-based products
No full textIn the frame of the general efforts to reduce atmospheric CO2 emissions different efforts are being carried out to stimulate the use of non-fossil energy sources and raw materials. Among these a significant role is played by the use of waste in Waste to Energy (WTE) plants. In this case a relevant problem is related to the determination of the proportion between the bio and the fossil derived fraction in CO2 atmospheric emissions since only the share of energy derived from the bio-fraction combustion can be labelled as "renewable". We discuss the potential of radiocarbon in this field by presenting the results of different campaigns carried out by analysing CO2 sampled at the stack of different power plants in Italy with different expected bio-content of the released carbon dioxide. The still open issues related to the calculation procedures and the achievable precision and accuracy levels are discussed
A new system for the simultaneous measurement of δ13C and δ15N by IRMS and radiocarbon by AMS on gaseous samples: Design features and performances of the gas handling interface
No full textWe present the general design features and preliminary performances of a new system for the simultaneous AMS-14C and IRMS δ13C and δ15N measurements on samples with masses in the μg range. The system consists of an elemental analyzer (EA), a gas splitting unit (GSU), a IRMS system, a gas handling interface (GHI) and a sputtering ion source capable of accepting gaseous samples. A detailed description of the system and of the control software supporting unattended operation are presented together with the first performance tests carried out by analyzing samples with masses ranging from 8 μgC to 2.4 mgC. The performances of the system were tested in term of stability of the ion beam extracted from the ion source, precision and accuracy of the results by comparing the measured isotopic ratios with those expected for reference materials
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