The LISEL@DREAMS project for isobar suppression by laser photodetachment
Dr Oliver Forstner1, Mr. Vadim Gadelshin2, Mr. Dominik Studer2, Prof. Klaus Wendt2, Dr. Kurt Stiebing3
1University Of Jena, Jena, Germany, 2University of Mainz, Mainz , Germany, 3University of Frankfurt, Frankfurt, Germany
LISEL@DREAMS (Low energy Isobar SEparation by Lasers at DREsden Accelerator Mass Spectrometry) is a recent project to widen the applications of AMS by extending the range of measurable (radio-) nuclides. AMS has proven to be a versatile tool capable of detecting a large number of long-lived radionuclides at the ultra-trace level – i.e. isotope ratios down to 10^-16. However, being a mass spectrometric method, it is limited by the presence of strong isobaric background. To overcome this imitation, we propose to remove the isobars already at the low-energy side by laser photodetachment. This method allows to selectively neutralize isobars by laser radiation, leaving the ions of interest intact. First studies were performed at the University of Vienna within the ILIAS project and gave promising results for the easier to be measured low-mass AMS isotopes Al-26 and Cl-36. Within the LISEL@DREAMS project this method will be for the first time applied to an AMS facility based on a 6 MV tandem accelerator. This should allow to measure all isotopes from around Z=50 up to the actinides. The first isotopes to be addressed with the new method will be Mn-53 and Fe-60. Both are currently only measurable at AMS facilities with more than 10 MV terminal voltage (after closure of the tandem accelerator lab of the LMU and TU Munich in Garching/Germany currently only available at the ANU in Canberra/Australia). The tunable Ti:Sapphire laser system is currently developed at the University of Mainz. Further on we foresee to apply this method to other rare isotopes, making LISEL@DREAMS a versatile machine for “all” isotopes. This will subsequently widen the applications and also the user community.
The required spectroscopic data especially for molecular anions will be gathered at the low-energy electrostatic storage ring FLSR at the University of Frankfurt. It has recently been upgraded with a source for negative ions and commissioning with lasers is currently taking place.
LISEL@DREAMS is a project funded by the German Federal Ministry of Education and Research BMBF.
Dr. Forstner is scientific associate at the University of Jena where he is project leader of the joint research project LISEL@DREAMS funded by the German ministry of education and research. His research focus is nuclear physics using atomic physics techniques. He received his PhD from the Technical University of Vienna for working with ion traps at ISOLDE/CERN. Afterwards he worked at VERA developing the ILIAS cooler device for laser ion interaction.