From tip to toe – Improvements of the DREAMS facility for the determination of volatile and heavy radionuclides

From tip to toe – Improvements of the DREAMS facility for the determination of volatile and heavy radionuclides

Pavetich, S.; Akhmadaliev, S.; Arnold, M.; Aumaître, G.; Bourlès, D.; Buchriegler, J.; Fifield, K.; Golser, R.; Keddadouche, K.; Martschini, M.; Merchel, S.; Rugel, G.; Srncik, M.; Steier, P.; Wallner, A.; Ziegenrücker, R.

Since the DREAMS (DREsden Accelerator Mass Spectrometry) facility [1] based on a HVE 6 MV Tandetron went operational in 2011, special effort was immediately devoted to upgrading the system for measurements of volatile elements e.g. Cl, I, and heavy elements e.g. actinides.
In the case of volatile elements, understanding and minimizing the ion source memory effect is a key issue for precise AMS-measurements [2,3]. For this purpose, one of the two original HVE sources was mechanically optimised. The new design has a more open geometry to improve the vacuum level and a modified target loading and positioning system, which allows exchanging the cathode aperture together with each target. To evaluate improvements of these modifications in comparison to other up-to-date AMS facilities [4], the long-term memory effect in the ion sources of VERA [5], ASTER [3] (Accélérateur pour les Sciences de la Terre, Environnement, Risques) and DREAMS [1] have been investigated by measuring samples of natural 35Cl/37Cl-ratio and samples containing highly enriched 35Cl (35Cl/37Cl ~1000). In these measurements the modified DREAMS ion source showed the lowest level of ion source memory effect and typically the fastest recovery [4].
To extend the measurement capabilities to actinides a time-of-flight system based on thin carbon foils and Micro Channel Plates was designed and constructed at DREAMS. For an optimal tuning of the system with low currents special beam diagnostic elements were manufactured. In cooperation with ANU first actinide samples were measured at DREAMS.

[1] S. Akhmadaliev et al., NIMB 294 (2013) 5.
[2] R. Finkel et al., NIMB 294 (2013) 121.
[3] M. Arnold et al., NIMB 294 (2013) 24.
[4] S. Pavetich et al., NIMB, accepted.
[5] M. Martschini et al., NIMB 269 (2011) 3188.

Keywords: Accelerator Mass Spectrometry; Cl-AMS; long-term memory effect; actinide AMS; Time-of-Flight; DREAMS

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    13th International Conference on Accelerator Mass Spectrometry (AMS-13), 24.-29.08.2014, Aix-en-Provence, France

Publ.-Id: 20135