Hannover 2003 – wissenschaftliches Programm
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MS: Massenspektrometrie
MS 3: Poster
MS 3.2: Poster
Dienstag, 25. März 2003, 16:30–18:30, Lichthof
Investigation of ion cooling in a gas-filled RF-quadrupole — •S. Elisseev1, A.F. Dodonov2, H. Geissel3, G. Münzenberg3,4, Y.N. Novikov5, W. Plaß1, C. Scheidenberger3, and Z. Wang1,3 — 1Justus-Liebig Universität, II. Physikalisches Institut, 35392 Giessen — 2InEPCP Chernogolovka, Russia — 3GSI, 64291 Darmstadt — 4Johannes Gutenberg-Universität Mainz, Institut für Physik, 55128 Mainz — 5PNPI St. Petersburg, Russia
The cooling and storage properties of a gas-filled radio-frequency quadrupole (RFQ) have been examined. The RFQ is coupled to a time-of-flight mass spectrometer with orthogonal extraction (Ortho-TOF MS), which will be used for mass measurements of exotic nuclei.The RFQ is used in two modes: in bunch mode the ions are accumulated and stored in the RFQ, in continuous mode the ions pass through the RFQ. In both modes the ion motion is cooled down to almost thermal energy of the buffer gas. An extensive investigation of the RFQ operated in both modes has been performed. For continuous and bunch modes the energy distribution of ions in the RFQ vs. pressure of the buffer gas, amplitude of the RF-field and number of the ions in the RFQ have been measured. In bunch mode, the properties of the trap, such as the maximum number of ions that can be stored and the survival time of ions in the trap vs. impurity level in the RFQ have been investigated. It has been shown that up to 2*105 Cs -ions can be stored for up to 500 ms, which is sufficient to reach good cooling perfomance. As a result of the study the optimised working conditions for the RFQ have been found.