Lichtgedanken 05

Rubrik 52 The abbreviation ISOLDE stands for »Isotope Separator On Line DEvice«. The BMBF is providing the funding for three years as part of its collaborative re- search support. Research groups at uni- versities in Greifswald, Jena, Cologne and Mainz, and at technical universities in Darmstadt and Munich, are receiving the funding. Developing highly sensitive detectors The research focuses on »exotic«, or short-lived, nuclei. Even when using state-of-the-art methods, it is often only possible to produce them at CERN, and only in small numbers. Therefore, highly sensitive detectors need to be developed to not only verify the exis- tence of the short-lived nuclei; but also, to accurately measure their properties— for example their size, dimensions and excitation spectrum. Nuclear physical methods, such as laser spectroscopy and mass spectrometry at low particle ener- gies, will be used for this purpose. On the other hand, new interest in the field of high-resolution nuclear spectroscopy for the impact and disintegration of nuclei has been sparked after ISOLDE was recently extended to the so-called HIE-ISOLDE: with Higher (H) Intensi- ties (I) and at higher Energies (E) for the particle beams. The research project at the University of Jena mainly focuses on making precise theoretical predictions for the isotopic shift of various open-shell atoms and ions. These theoretical foundations are needed for the planning and evaluation of the laser spectroscopic investigati- ons at ISOLDE, as well as for the spec- troscopy of the super heavy elements nobelium and lawrencium. In many cases, precise structural calculations for the isotopic parameters are required in order to be able to reliably extract the core properties from the experimen- tally measured (isotopic) shifts to the transition frequencies. »The isotopic parameters, which describe the elec- tronic response to the different masses and charge distributions of isotopes, are often sensitive to relativistic contributi- ons and electronic correlations and can, therefore, only be adequately descri- bed with correlated many-particle me- thods», explains the Jena-based project leader, Prof. Dr Stephan Fritzsche. »The theoretical developments and calculati- ons planned in our project will be used directly in the preparation and analysis of the laser spectroscopic experiments conducted by the research groups in Darmstadt, Heidelberg and Mainz«, continues the theoretical physicist, who works at the Friedrich Schiller Universi- ty and at the Helmholtz Institute in Jena. From the experiments, the researchers hope to gain new insights, for instance into the core physical processes in stars. In addition to this basic research, the radioactive nuclei provided by ISOLDE and the experimental methods will also be used for the investigation of solid ob- jects as well as medical issues.  Researching exotic nuclei with ISOLDE The German Federal Ministry for Education and Research (BMBF) is supporting six German universities—including the Friedrich Schiller University—with 2.4 million euros in their research into ISOLDE. This is the name of a device used for the production of radioactive ion beams at the nuclear research centre CERN in Geneva. The scientists hope to use their experiments on »exotic« atomic nuclei to make discoveries about nuclear-physical processes in stars, amongst other things. BY JÜRGEN REES Prof. Dr Stephan Fritzsche and his team want to provi- de theoretical developments and calculations, which can be directly used for the preparation and analysis of laser spectroscopic experiments.