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Cohen, Anthony S.; O'Nions, R. Keith and Belshaw, Nicholas S.
(1992).
DOI: https://doi.org/10.1016/0168-1176(92)80020-2
Abstract
Mass spectrometric methods are presented for the precise determination of the isotopic compositions of uranium, thorium and radium. M+ ions were produced by thermal ionisation. Analysis involved either a dynamic routine using the Daly detector or a static routine employing both the Daly detector and off-axis Faraday detectors. Instrument performance was assessed using a set of uranium standards, CBNM IRM 072. The response of the Daly detector was linear up to ratios of at least 5 x 10(4) and when operated dynamically it is ideally suited to the measurement of ion beams in the range 5-1 x 10(5) cps. The static mode of analysis was employed successfully for the measurement of isotope ratios up to 5 x 10(5).