1. Accelerator Technology and Applied Physics Division, Lawrence
Berkeley National Laboratory, Berkeley, California 94720,
USA
2. Ilmenau University of Technology, Department of
Microelectronics and Nanoelectric Systems, 98684 Ilmenau, Germany
3. The Molecular Foundry, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, USA
4. GSI Helmholtz Center for Heavy Ion research,
64291 Darmstadt, Germany
5. Technische Universität Darmstadt, 64287
Darmstadt, Germany