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HITRAP Résumé de rapport

Project ID: HPRI-CT-2001-50036
Financé au titre de: FP5-HUMAN POTENTIAL
Pays: United Kingdom

Setup for laser spectroscopy of trapped highly charged ions

We designed a trap to perform laser spectroscopy of trapped and cooled highly charged heavy ions. This trap is a cylindrical open-end cap Penning trap which combines resistive cooling and the rotating wall technique with high-precision laser spectroscopy. We have performed detailed calculations in order to optimise the trap design so that good fluorescence rates can be expected. The results of these calculations have been incorporated in the trap design and this work is also published (Rev. Sci. Instrum.).

We aim to measure ground state hyperfine splitting in highly charged heavy ions, such as hydrogen-like lead and lithium-like bismuth, by laser spectroscopy. These ions will be delivered by the HITRAP re-injection channel (from the cooler trap), and trapped, cooled and compressed in our spectroscopy trap. By using laser spectroscopy it is possible to obtain high-accuracy results, which are 3 orders of magnitude better than the previous ones.

For pilot experiments at Imperial College in London (2006/2007), we will use our existing super conducting magnet (warm bore, no radial access) and design and build a simple ion source that can produce singly/doubly charged ions, which have magnetic dipole transitions in the visible range. For the final measurements at GSI in Darmstadt (2007/2008), we will use the super conducting magnet from the RETRAP experiment (cold bore, radial access). Our spectroscopy trap has been designed to be compatible with both magnet systems. The electrodes of our Penning trap are being constructed in our workshop and, by the end of 2005, the spectroscopy trap will be ready for first test measurements at Imperial College.

Final measurements on highly charged ions can only be performed once the HITRAP set up in the re-injection channel has been completed, which is anticipated to be near the end of 2007. Unfortunately, most of the advanced techniques used in our trap, i.e. electronic cooling and detection and the rotating wall technique, can only be tested effectively when the trap is operated at cryogenic temperatures (RETRAP magnet) and highly charged ions, coming from the HITRAP re-injection channel, are used.

We have also carried out studies of new designs for scalable Penning traps and constructed a prototype permanent magnet Penning trap, which is currently under test. Our recent experiments involving laser spectroscopy and laser cooling of singly-charged ions in Penning traps have led to a deeper understanding of the dynamics of ions in traps under excitation from quadrupole fields, which is highly relevant for the operation of the HITRAP Penning trap. These experiments have also given us more experience of laser spectroscopic techniques including detection of low levels of light, which is important for the planned experiments at HITRAP.


Richard THOMPSON, (Professor, group leader)
Tél.: +44-207-5947505
Fax: +44-207-5947777