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Andre
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The first half time of radioactive carbon (14C) that got some consensus is the Libby date of 5568 years, which is still used..
See Wikipedia
The latter is very fortunate, calibration tables, like the current INTCAL04, being independent of half times for determining age. So calibrated datings are 'correct' albeit with considerable margins. What is not correct however, with wrong half times, is the presumed original concentration of radiocarbon (delta14C) in the atmosphere and in the calibration table it can be seen that the concentration is assumed to increase strongly with age.
This could be partly explained by the difference in atmospheric CO2 concentration, the speed of the carbon cycle and the production rate of 14C as function of the cosmic radioactivity. But a lot of those changes don't make sense and up until now, there have been little if any serious attempt to explain the strong variation in assumed 14C ratios. Could it be that the half time is wrong instead and that this accumulation of 14C is actually non existent?
Such a simple explanation I did not even dare to challenge myself, expecting that determining halftimes involves advanced, well established physics, way above my perception. However:
http://radiocarbon.ldeo.columbia.edu/pubs/2006Chiu.pdf
Consequently, The most suitable half time for radio carbon should be 6030 years. I do wonder if such a rebellion has even a remote change to get accepted in the most conservative environment ever.
See Wikipedia
Carbon dating was developed by a team led by Willard Libby. Originally a Carbon-14 half-life of 5568±30 years was used, which is now known as the Libby half-life. Later a more accurate figure of 5730±40 years was determined, which is known as the Cambridge half-life. However laboratories continue to use the Libby figure to avoid inconsistencies when comparing raw dates and when using calibration curves to obtain calendrical dates.
The latter is very fortunate, calibration tables, like the current INTCAL04, being independent of half times for determining age. So calibrated datings are 'correct' albeit with considerable margins. What is not correct however, with wrong half times, is the presumed original concentration of radiocarbon (delta14C) in the atmosphere and in the calibration table it can be seen that the concentration is assumed to increase strongly with age.
This could be partly explained by the difference in atmospheric CO2 concentration, the speed of the carbon cycle and the production rate of 14C as function of the cosmic radioactivity. But a lot of those changes don't make sense and up until now, there have been little if any serious attempt to explain the strong variation in assumed 14C ratios. Could it be that the half time is wrong instead and that this accumulation of 14C is actually non existent?
Such a simple explanation I did not even dare to challenge myself, expecting that determining halftimes involves advanced, well established physics, way above my perception. However:
http://radiocarbon.ldeo.columbia.edu/pubs/2006Chiu.pdf
An under-estimate of the 14C half-life is a possible explanation for excessively elevated Δ14C values. If the calorimetry estimated 14C half-life, 6030 years, is validated by new half-life measurements, it could explain much of the linear component of the radiocarbon calibration curves and the discrepancy between Δ14C values derived from corals and modeled Δ14C values based on paleointensity combined with a range of carbon cycle scenarios. We conclude that the variation in paleointensity and a possible offset in the absolute value of 14C half-life together control the overall shape and amplitude in the Δ14C record for the past 50,000 years.
A re-determination of the 14C half-life is urgently needed for radiocarbon-based research. After the 14C half-life is accurately measured and eplicated by multiple techniques, our coral data will provide an opportunity to examine subtler carbon cycle influences on the younger half of the Δ14C record.
Consequently, The most suitable half time for radio carbon should be 6030 years. I do wonder if such a rebellion has even a remote change to get accepted in the most conservative environment ever.
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