Final Report
The final report package includes the final date report, a statement
outlining our analytical procedures, a glossary of pretreatment terms, calendar
calibration information, billing documents (containing balance/credit information and the
number of samples submitted within the yearly discount period), and peripheral items to
use with future submittals. The final report includes the individual analysis method, the
delivery basis, the material type and the individual pretreatments applied. The final
report will be sent by mail, fax or e-mail, where available.
Pretreatment
Pretreatment methods are reported along with each result. All
necessary chemical and mechanical pretreatments of the submitted material are applied at
the laboratory to isolate 14C which may best represent the time event of interest. When
interpreting the results, it is important to consider the pretreatments. Some samples
cannot be fully pretreated, making their 14C ages more subjective than samples which can
be fully pretreated. Some materials receive no pretreatments. Please read the pretreatment
glossary.
Analysis
Materials measured by the radiometric technique are analyzed by
synthesizing sample carbon to benzene (92% C), measuring for 14C content in a
scintillation spectrometer, and then calculating for radiocarbon age. If the Extended
Counting Service is used, the 14C content is measured for a greatly extended period of
time. AMS results are derived from reduction of sample carbon to graphite (100 %C), along
with standards and backgrounds. The graphite is then sent for 14C measurement in an
accelerator-mass-spectrometer located at one of six collaborating research facilities, who
return the results to us for verification, isotopic fractionation correction, calendar
calibration, and reporting.
The
Radiocarbon Age and Calendar Calibration
The
"Conventional C14 Age (*)" is the result after applying C13/C12 corrections to
the measured age and is the most appropriate radiocarbon age (the "*" is
discussed at the bottom of the final report). Applicable calendar calibrations are
included for organic materials and fresh water carbonates between 0 and 20,000 BP. If
certain calibrations are not included with a report, the results were either too young, to
old, or inappropriate for calibration. |
