Research objectives

The EUROTRAPS network aims at a coordinated European effort to enable:

• high-accuracy tests of the theory of Quantum Electrodynamics (QED) in extremely strong electromagnetic fields by measuring
• masses of bare and few-electron highly charged heavy ions up to U⁹²⁺, U⁹¹⁺, U⁹⁰⁺....
• the g-factors in the ground state of hydrogen-like ions up to U⁹¹⁺ and
• comparing with accurate many-body and QED calculations.

The network is a development of the highly successful SCIENCE project SCI*CT 910638 that started in June 1991. The Penning trap mass spectrometer SMILETRAP (Stockholm-Mainz-Ion-LEvitation-TRAP) for mass determinations of light and medium heavy highly charged ions has been constructed and tested at Mainz, shipped to Stockholm, installed and connected to the electron beam ion source CRYSIS at the Manne-Siegbahn Laboratory (MSL)/Stockholm in close collaboration between groups from Mainz and Stockholm. Recent mass measurements have reached an accuracy of 10^-9.

By the use of ion sources and ion traps now available, exotic and rare particles like highly charged ions can be confined, manipulated, cooled and observed over long periods of time, in principle forever. Thus, traps are the tool of choice for many physical problems where extremely high precision is required. The cryogenic Penning trap system HITRAP (Highly Charged Ions TRAP) has been developed during the past two years for g-factor and mass measurements of highly charged heavy ions in close collaboration between the groups mainly from Mainz and GSI. Presently tests are performed with light ions like ¹²C⁵⁺, and the sensitivity was found to be high enough to detect one single ion. In order to make rigorous comparisons between the experiments described above and theory, new schemes for many-body and QED calculations have recently been developed by members of the network.

An essential part of the suggested network is a collaboration between the experimental and theoretical groups. The theoretical groups have long experience in atomic many-body calculations and the Göteborg group has also in recent years been quite successful in QED calculations. By a more intense collaboration between the theory groups - and in particular between the theory and the experimental groups - important progress can be expected in this field of research.

The proposed network represents an enlargement of the cooperation aiming at:

• further development of many-body and QED techniques for accurate calculations of binding energies, g-factors and lifetimes in few-electron ions,
• improving the accuracy of mass determinations to 10^-10 or better,
• setting up the new facility HITRAP for high-accuracy mass and g-factor measurements of heavy highly charged ions at the heavy-ion accelerator GSI/Darmstadt,
• putting expertise in Penning trap techniques at the disposal of European groups in need of traps and also at the disposal of industry, in particular by setting up a Penning trap system at the microtron in Aarhus as accumulator and cooler of positrons, and developing a trap for weak interaction studies at Leuven/Louvain-la-Neuve and CERN.

The network joins all European groups involved in high-precision atomic and nuclear spectroscopy by utilising Penning traps as well as related theory groups in Europe.