The stunning improvements in the performance of mass spectrometers during the past four or so decades, starting with the landmark paper by Wasserburg et al.
(1969), have not been accompanied by any comparable improvement in the accuracy of the decay constants (Begemann et al.
With the measurement technology having improved, the determinations over the last 20 years have resulted in close agreement between the four determination methods—direct physical counting and in-growth experiments, and radioisotope age comparisons using molybdenites and groups of meteorites. In Applications of radiogenic isotope systems to problems in geology, ed.
Thus the per year respectively have now been adopted for standard use by the uniformitarian geological community. This value is essentially identical to the best of the recent determinations using groups of iron meteorites.
Indeed, both the U ratio that is critical to that method (Brennecka and Wadhwa 2012; Hiess et al 2012).
Therefore, the aim of this contribution is to further document the methodology behind and history of determining the present decay constants and half-lives of the parent radioisotopes used as the basis for the long-age dating methods. Cambridge, United Kingdom: Cambridge University Press. However, even uncertainties of only 1% in the half-lives lead to very significant discrepancies in the derived radioisotope ages. The recognition of an urgent need to improve the situation is not new (for example, Min et al. It continues to be mentioned, at one time or another, by every group active in geo- or cosmochronology (Schmitz 2012). These values are based on determinations recalibrating Re-Os model ages of molybdenites by forcing them (essentially by circular reasoning) to agree with the U-Pb concordia-Pb-Pb intercept ages of zircons from the same 11 magmatic-hydrothermal systems dating from ca. It is also within the ± uncertainty range of the half-life values obtained by the best of the physical direct counting and in-growth experiments. Yet, in spite of such experiments directly measuring Os respectively, preference has been given to the half-life value determined by forcing the Re-Os data to agree with U-Pb dates. The reliability of the other two assumptions these absolute dating methods rely on, that is, the starting conditions and no contamination of closed systems, are unprovable. Cambridge, United Kingdom: Cambridge University Press. Yet these can supposedly be circumvented somewhat via the isochron technique, because it is independent of the starting conditions and is sensitive to revealing any contamination, which is still significantly better than any radioisotope method for determining the ages of rock formations. On the other hand, it could be argued that this discarding of data points which do not fit the isochron is arbitrary and therefore is not good science, because it is merely assumed their “aberrant” values are due to contamination rather than that being proven to be so. The fundamental constants and their time variation. Indeed, in order to discard such outliers in any data set, one must establish a reason for discarding those data points which cannot be reasonably questioned. We need to explore just how accurate these determinations are, whether there really is consensus on standard values for the half-lives and decay constants, and just how independent and objective the standard values are from one another between the different methods. Of course, it is to be expected that every long-lived radioactive isotope is likely to show similar variation and uncertainty in half-life measurements because these are difficult measurements to make.