Tübingen 2003 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 12: Poster-Sitzung: Instrumentation und Anwendungen

HK 12.5: Poster

Dienstag, 18. März 2003, 13:30–15:30, Foyer

The gas cell and extraction RFQ for SHIPTRAP — •J. Neumayr, D. Habs, S. Heinz, J. Szerypo, P. Thirolf, V. Varentsov, F. Voit, and A. Wilfart — Sektion Physik der Uni M"unchen, Am Coulombwall 1, 85748 Garching

The SHIPTRAP ion trap facility at GSI consists of a gas cell for stopping and thermalizing high-energy recoil ions from SHIP, a radiofrequency quadrupole ion guide for extraction of the ions from the gas cell (extraction RFQ), a linear RF trap for accumulation and bunching of the ions (RFQ buncher), and a tandem Penning trap system for isobaric purification and high precision mass measurements.

The gas cell and the extraction RFQ have been designed, built and tested at Munich. The cell is designed to stop heavy recoil ions from SHIP in He gas. For the transport of the stopped ions inside the SHIPTRAP gas cell RF and DC fields are used to guide the ions towards the nozzle where they are extracted via the gas flow. In the segmented extraction RFQ the ions are separated from the neutral gas and cooled transversely for the following transfer into the RFQ buncher.

The Munich test setup allows both off-line and on-line tests. For off-line measurements the test ions can be produced inside the cell by a pulsed Nd-YAG laser. Tests were performed to optimize the extracting and guiding fields and for measurements of extraction times as a function of the gas pressure. Besides the extraction characteristics the second main issue was the stopping behaviour of ion beams. This was studied using ion beams from the Tandem accelerator in Garching at different energies entering the gas cell through a thin metall entrance window.