Opportunities and Limits of AMS with 3-MV Tandem Accelerators

Peter Steier^a, Robin Golser^a, Vitaly Liechtenstein^b, Walter Kutschera^a, Alfred Priller^a, Christof Vockenhuber^a, and Anton Wallner^a.

^a VERA Laboratory, Institut für Isotopenforschung und Kernphysik der Universität Wien, Währinger Straße 17, A-1090 Vienna, Austria

^b Russian Research Center, „Kurchatov Insitute“, Institute of Nuclear Fusion, 123182 Moscow, Russia

Abstract

With the Vienna Environmental Research Accelerator (VERA, based on a 3-MV tandem accelerator) we have systematically explored the limitations due to terminal voltage, both by modelling and by experiments. If no stable atomic isobars exist, e.g. for ²³⁶U or ²⁴⁴Pu, the same detection limits as for large machines have been achieved. In cases where isobar separation is required, the achievable energy is the limitation.

To study isobar separation experimentally, we use a new method called DTOF: the different energy loss in a foil is measured with a time-of-flight (TOF) detector. Separation of ³⁶Cl from ³⁶S is possible. With Diamond Like Carbon (DLC) stripper foils (0.6 µg/cm²) and by pushing our Pelletron tandem to 3.6 MV, we achieved a significant increase in energy compared to gas stripping at 3 MV: e.g., ³⁶Cl⁷⁺ at 28.8 MeV instead of ³⁶Cl⁵⁺ at 18 MeV can be used.

PACS: 29.30.Aj; 29.17.+w

Keywords: AMS, isobar separation, terminal voltage, limitations