[1] Max Planck Inst Gravitat Phys, Albert Einstein Inst, Muhlenberg 1, D-14476 Potsdam, Germany
[2] Univ Maryland, Dept Phys, College Pk, MD 20742 USA
[3] Humboldt Univ, Inst Phys, Zum Grossen Windkanal 2, D-12489 Berlin, Germany
[4] Humboldt Univ, IRIS Adlershof, Zum Grossen Windkanal 2, D-12489 Berlin, Germany