Rare isotope detection with tandem accelerators

Abstract

The rare radioactive isotopes 10Be, 14C, 26Al, 32Si, 36Cl and 129I have been detected at or near natural levels without prior isotopes enrichment by using negative ions, molecular dissociation with tandem accelerators, atom counting and isobar identification. Ratios of 14Cl/ 12C and 36Cl/Cl near 10 −16 have been reached in measurements during the development of radiocarbon and 36Cl dating of milligram samples. Recent studies of the low level abundances (<1 ppb) of the rare stable isotopes of platinum and iridium in clays at and near the Cretaceous-Tertiary boundary have demonstrated the value of the techniques for the detection of rare stable isotopes. The application of the techniques to geochronology is discussed.