The ILIAS project for selective isobar suppression by Laser photodetachment

At the VERA Laboratory of the University of Vienna a facility for studying selective isobar suppression of negative ions by Laser photodetachment is currently under construction. The ILIAS (Ion Laser InterAction Setup) setup consists of a negative ion spectrometer providing mass separated beams of negatively charged atomic or molecular ions with energies up to 30 keV. The negative ions are produced in a Middleton type cesium sputter ion source. After mass selection the ions are stopped in a gas-filled radio frequency quadrupole cooler where they overlap with a strong continuous wave Laser beam. By careful selection of the photon energy unwanted isobars are neutralized while the ions of interest remain intact. With this scheme a selective suppression of isobars can be achieved. After a description of the setup and a status report of the commissioning of the negative ion spectrometer, the progress of the construction of the RFQ cooler will be presented. As an outlook the first photodetachment experiments with the RFQ cooler and a possible scheme for application of this new method to a 3 MV AMS facility will be described. (author)