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U-series isotopes

We are currently utilizing 234U/238U measurements in isotope hydrology studies. For larger samples, measurement of the 234U/238U ratio is accomplished by a two sequence dynamic analysis, peak-switching the 235U beam between Faraday cup and Daly detector to establish a real time gain, and fractionation correcting relative to the known 235U/238U ratio. Alternatively, for small samples, the same measurment is made by peak jumping all isotopes (including 238U) into the Daly detector due to its large dynamic range. Using the latter method and maintaining a 1 Mcps 238U beam, the external reproducibility of the 234U/238U ratio in an in-house secular equilibrium U standard is 0.00005493 ± 10 (0.18%; 1-sigma, n=37; accepted value=0.00005489).

Isotope diagram