Not biased. Hands on experience. The detectors are identical to those for RATE. The detection method is biased when it can't filter out all cosmic rays and electronic noise.
The AMS used is that from tne of the better radiocarbon labs in the US.
How does the cosmic rays and electronic noise occur in the AMS labs?
There was a critic named Bertsche and he referenced a Taylor and Southon (2007) paper who claimed the C14 was not intrinsic to the diamonds themselves. I suppose that would include you cosmic rays and electronic noise. I copied and paste the following for diamonds from Dr. John Baumgardner as rebuttal:
"In his 2008 critique Bertsche references the Taylor and Southon (2007) paper describing their application of accelerator mass spectrometry (AMS) to natural diamonds. Bertsche calls attention to the authors’ statement, “The oldest 14C age equivalents were measured on natural diamonds which exhibited the highest current yields.” He claims that this means that the measured 14C cannot be intrinsic to the diamonds themselves. What Bertsche fails to mention is that the correlation of low 14C level with high ion current was restricted to only a subset of the authors’ data. Such a correlation did not exist across all the samples the authors tested and reported. That pattern occurred only among the eight diamonds listed in part B of Taylor and Southon’s Table 2. Five of these diamonds were mounted with silver powder beneath them in the 1.6 mm holes drilled in the aluminum cathode sample holder, while the other three did not have the silver powder. The purpose of the silver powder was to enhance the thermal conductivity between the diamond and the aluminum sample holder. This difference in mounting procedure resulted in the surprising and unexplained increase in ion current and decrease in the number of 14C atoms detected as shown in part B of Table 2 for the samples without the silver powder.
How do the authors interpret this pattern? They state, “Previous tests showed that 14C count rates from silver powder cathodes were comparable with those from diamonds. Because of this and because the silver packing was largely shielded from the cesium beam by the diamonds themselves, the excess 14C was therefore probably due to differences between diamonds or run-to-run changes in the spectrometer, not from carbon in the silver powder.” Note that the authors emphatically do
not attribute the higher 14C counts, as Bertsche claims, to ion source memory contamination. One good reason for the authors’ caution was the
absence of this trend of higher 14C count with lower ion current in the measurements reported in part A of Table 2. Part A results are from a single diamond that was cleaved into six separate pieces. Results for these six samples show little variation in 14C levels despite moderately large differences in ion current. For example, samples 12674 and 12675 yielded the same 14C value of 0.015 pMC, despite the fact that sample 12675 displayed a 50% higher beam current compared with sample 12674. The correlation Bertsche is relying upon for his interpretation is altogether missing for the six samples listed in part A of Table 2. The simplest explanation for the trend in the eight samples in part B is that it is associated with the presence or absence of the silver powder. Precisely how the silver powder might be producing the observed trend is not clear. Indeed, the authors acknowledge their inability to provide a confident explanation.
Regardless of the actual cause, the glaring fact remains that Taylor and Southon detected levels of 14C in the diamonds they analyzed that were all well above the intrinsic sensitivity of their AMS hardware. That intrinsic sensitivity, typically observed with a blank aluminum sample holder (with no sample or silver powder present) is on the order of 0.00056 pMC, corresponding to about 100,000 years under the standard assumption of a constant past atmospheric 14C level. Note that the level measured for samples 12674 and 12675 are more than
25 times greater than this normal instrument background.
It is important to emphasize that placing the diamonds directly in holes bored in the instrument's cathode sample holder eliminates all of the potential sources of 14C contamination listed in Table 1 of Taylor and Southon's paper except for items (1), 14C intrinsic to the sample itself, and (7) instrument background. The authors argue that most potential sources of instrument background can be excluded for their system. They show from their investigations that contamination from CO2 and other carbon-containing species adhering to the diamond surface can now be effectively ruled out as well. This means that contamination from ion source memory is largely removed from the table. What then is left? It is item (1), namely, 14C intrinsic to the sample itself! The authors acknowledge this reality in the final sentence of section 1 of their paper when they state, “14C from the actual sample is probably the dominant component of the ‘routine’ background.” This statement directly contradicts Bertsche's assertion that these authors interpret their measured 14C values as “instrument background, primarily due to ion source memory.” The overall conclusion is that the 14C levels in natural diamond reported by Taylor and Southon are consistently far above the levels one would expect if these diamonds were truly more than a few hundred thousand years old. Despite the conflict it raises for Bertsche’s worldview, the Taylor and Southon paper tangibly strengthens the case that AMS instrument background can be eliminated, to a high degree of certainty, even as a remotely possible explanation for the substantial 14C levels measured so routinely in carbon-bearing samples from deep within the geological record.
Furthermore, despite Bertsche’s emphasis on the diamond measurements, to me whether or not there is 14C in diamonds is a relatively minor issue. The dramatically more important issue, as emphasized in our RATE report, is the consistent presence of even higher levels of 14C in all fossilized living things which still retain some carbon. That fact is powerful and indisputable support that the earth is young and that the Genesis Flood really did occur not so long ago.
John Baumgardner
November 2014"
Are the RATE Results Caused by Contamination?
Now, the carbon AMS measurements are a bit different. We have two different methods producing two different ages. Both RATE and the AMS lab seem to be saying there was no in situ or lab contamination added to the samples in the lab.
"During the RATE (
Radioisotopes and the
Age of
The
Earth) research project at the
Institute for Creation Research, co-sponsored by the
Creation Research Society, some of the research effort was focused on investigating radiocarbon (carbon-14) dating. This is one of the
radioactive dating methods, but because carbon-14 decays relatively rapidly it only provides “ages” in the range of tens of thousands of years. In fact, if every atom making up the earth was carbon-14, even after just 1 million years there would be absolutely no atoms of carbon-14 left, because they would have all decayed away, based on today’s measured half-life! That’s why radiocarbon dating isn’t used to date rocks at millions of years.
The RATE radiocarbon research first focused on demonstrating that significant detectable levels of carbon-14 are present in ancient coal beds.
1,
2 Ten samples from U.S. coal beds, conventionally dated at 40–320 million years old, were found to contain carbon-14 equivalent to ages of around 48,000–50,000 years. The laboratory did repeat analyses and confirmed that this carbon-14 in the coals was not due to any contamination either
in situ in the samples or added to the samples in the laboratory. Of course, these would not be the true ages of these coal beds, because these 48,000–50,000 year ages are calculated at the present-day level and production rate of radiocarbon. The fact that all these coal beds yield radiocarbon ages in the same “ballpark” is consistent with them all having been formed at the same time in a recent catastrophic event. This is, of course, consistent with masses of pre-Flood vegetation being swept away and buried on a huge scale globally during the cataclysmic
Genesis Flood.
Buoyed by this success, the RATE radiocarbon research next checked for carbon-14 in diamonds. Diamonds are the hardest known natural substance and resist physical abrasion. Also, the chemical bonding of the carbon in diamonds makes them highly resistant to chemical corrosion and weathering. Diamonds also repel and exclude water from adhering to their surfaces, which would eliminate any possibility of the carbon in the diamonds becoming contaminated. Sure enough, the diamonds submitted for radiocarbon analyses did contain detectable, significant levels of carbon-14, equivalent to an age of around 55,000 years. Again, the laboratory did repeat analyses and discounted any possibility that this carbon-14 was due to contamination,
in situ to the diamonds or added in the laboratory. At 1–2 billion years old, these diamonds, which are formed deep inside the earth, are regarded as being related to the earth’s early history. Therefore, it was concluded that carbon-14 in these diamonds was consistent with a
young age for the earth itself.
Confirmation that there is
in situ carbon-14 in diamonds has now been reported in the conventional literature.
3 R.E. Taylor of the Department of Anthropology at the University of California–Riverside and of the Cotsen Institute of Archaeology at the University of California–Los Angeles teamed with J. Southon at the Keck Accelerator Mass Spectrometry Laboratory of the Department of Earth System Science at the University of California–Irvine to analyze nine natural diamonds from Brazil. All nine diamonds are conventionally regarded as being at least of early Paleozoic age, that is, at least several hundred million years old. So, if they really are that old they should not have any intrinsic carbon-14 in them. Eight of the diamonds yielded radiocarbon “ages” of 64,900 years to 80,000 years. The ninth diamond was cut into six equal fragments, which were each analyzed. They yield essentially identical radiocarbon “ages” ranging from 69,400 years to 70,600 years. This suggests the carbon-14 was evenly distributed through this diamond, which is consistent with it being intrinsic carbon-14, and not contamination. Interestingly, samples of Ceylon graphite from Precambrian metamorphic rock (conventionally around 1 billion years old) were analyzed at the same time and yielded radiocarbon “ages” of from 58,400 years to 70,100 years.
These results, from a different radiocarbon laboratory to that used by the RATE group, confirm that there is intrinsic carbon-14 in natural diamonds. Therefore, they cannot be hundreds of millions or billions of years old, as there is no other current credible explanation for the presence of this carbon-14. Less carbon-14 was found in the diamonds in this study reported in the conventional literature. That was because the diamonds were mounted directly in the beam within the analytical instrument, whereas in the RATE study the diamonds were combusted to convert the carbon to carbon dioxide, which was then converted to graphite that was analyzed in the instrument. That process may have introduced some more carbon-14 to the analyses.
The University of California scientists, of course, did not conclude that the diamonds they analyzed are evidence that the earth is young. Instead, they interpreted these 64,900–80,000 year “age” to represent one component of “machine background” in the analytical instrument. Yet this begs the question as to why then did the Precambrian graphite contain on average more carbon-14 to yield younger ages than the diamonds? And why did the diamonds have such different carbon-14 contents to yield different apparent radiocarbon “ages”? Because the same instrument was used to analyze all the diamonds and the graphite, the results should surely have all been affected by the same “machine background.” Rather, these results may further confirm the conclusions of the RATE radiocarbon project that natural diamonds, which are related to the earth’s early history, show evidence of being only thousands of years old and provide noteworthy support that the earth is young."
Radiocarbon in Diamonds Confirmed
I'll respond to your other comments in a separate thread.
, not me 
.
