A Close Look at Matter

In everyday life the matter which surrounds us seems to be continuous. Only by physics methods a hierarchy of structures becomes visible. Many solid bodies have a crystalline or polycrystalline structure. If we look closer at matter, we realize that these crystals are made of atoms; looking closer at atoms we discover that they have electron shells and an atomic nucleus. The nucleus itself again consists of nucleons, positively charged protons and electrically neutral so-called neutrons. Since the 1970s we know that also nucleons have a substructure.

Together with the well known electrons these particles - dubbed quarks - are considered today to be the elementary building blocks of matter. The structure of matter can thus be unrevealed like the generations of a Russian matrioshka doll. Starting from macroscopic dimensions, the Figure covers 17 orders of magnitude in the size of the objects under investigation until we reach the level of quarks and electrons.

The research program at GSI includes work in all these areas. It is structured as follows: A large fraction of the resources goes into nuclear physics, atomic physics as well as plasma physics; as we will see these fields have research activities in their own right but at the same time they have an important impact on astrophysics and cosmology.

Accelerator developments have led to new technologies and new accelerator structures, investigations in solid state physics to the development of new materials with specific properties and research in biophysics to medical applications like tumor therapy. The heart of the research program is the accelerator facility. The UNILAC commissioned in the year 1975 accelerates ions to approximately 10 % of the velocity of light. The word universal underlines that all ions from hydrogen to uranium can be accelerated.

In the year 1990, the Schwerionensynchrotron SIS and the Experimental Storage Ring ESR were added to the facility, now providing ion beams with velocities up to 90% of the velocity of light. In 1999, the UNILAC was modified to further increase the available beam intensities, in particular for heavy ions like lead and uranium.

In the coming years, the international accelerator center called FAIR (Facility for Antiproton and Ion Research) — one of the largest research projects in Europe — will be built adjacent to GSI.