First data of Uranium-236 in the North Sea

The ETH Zurich AMS facilities: Performance parameters and reference materials

“…Using this technique the 36 S suppression increased from typical 1:20,000 to 1:100,000. Both stable ion currents, 35 Cl and 37 Cl are measured in FCs in the analyzing chamber adjacent to the gas ionization detector (Fig. 1).…”

“…Typical ion currents of 35 Cl À are between 5 and 10 lA; the transmission is around 17% ( Table 2). A gradually decreasing transmission during the measurement is a clear indication that the stripper foil has reached the end of its lifetime and has to be replaced.…”

“…Measurement cycles with counting rates above 1000 counts per second (usually at the very beginning of the sputtering process and when the sample material is almost used up) are excluded from routine analysis. Samples for in situ measurements are usually prepared by adding a known amount of 35 Cl spike material with a purity of 99.82% [28]. With the high 36 S suppression the 36 Cl/Clratio of the blank is (1-2) Â 10 À15 and dominated by real 36 Cl events from cross-contamination in the ion source or during sample preparation.…”

“…Over the past decade the TANDY was used as prototype machine to explore the multi-isotope capabilities of low energy AMS and it soon turned out that it is a powerful and flexible device for AMS analyses of radionuclides over the entire mass range ( 10 Be to the actinides). Since its construction the TANDY system has been significantly modified in order to improve its performance comprising the development of new gas ionization detectors including its electronics [33,34], the modification of the ion source and the installation of a second HE magnet [10], the replacement of the coils of the LE magnet to increase its bending power, and the installation of a more flexible beam switching system on the LE side [35]. Today, the TANDY is routinely used for AMS measurements of 10 Be, 41 Ca, 129 I, and the actinides.…”

“…236 Uranium. During a routine AMS measurement of 236 U the counting rate of two U-isotopes ( 233 U and 236 U) is measured with the gas ionization detector at the end of the beamline while the ion current of 238 U is determined with a FC after the first HE magnet [35]. The isotopic ratio measurements are performed by alternating between two configurations.…”