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University of Pennsylvania Radiocarbon Dates XIV
Abstract
This date list includes those series of samples completed in this laboratory as of December 1970. The B.P. ages are based upon A.D. 1950, and are calculated with a half-life value of 5568 yr. All samples were counted at least, twice for periods of not less than 1000 minutes each. Errors quoted are derived from measurement of samples, background, and modern-age calibration, but do not include any half-life error. All samples were pretreated with 3N HCI, and some, where noted, were given additional pretreatment with 2% NaOH for the removal of possible humic contaminants.
Standard calibration samples are 126-yr-old oak samples which, when corrected for age, have C14 contents equal to 95% of the NBS oxalic acid standard. The C13 relationship between the Oak standard and NBS limestone standard #20 is -25.7 + 1.3% as measured on the University of Pennsylvania mass spectrograph. Where 6013 is reported (cf. P-1621 and P-1544) and the results accordingly corrected for isotopic fractionation, the C13 relationship has been measured with respect to the Oak standard.
Standard calibration samples are 126-yr-old oak samples which, when corrected for age, have C14 contents equal to 95% of the NBS oxalic acid standard. The C13 relationship between the Oak standard and NBS limestone standard #20 is -25.7 + 1.3% as measured on the University of Pennsylvania mass spectrograph. Where 6013 is reported (cf. P-1621 and P-1544) and the results accordingly corrected for isotopic fractionation, the C13 relationship has been measured with respect to the Oak standard.