15min:

A. W. WIEDERKEHR, S. D. HOGAN, H. SCHMUTZ, M. ANDRIST, B. LAMBILLOTTE AND F. MERKT, Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zurich, Switzerland.

With the goals of: (i) performing ultra-high resolution spectroscopy with long interaction times between a cloud of cold atoms or molecules and a narrow bandwidth radiation field, and (ii) studying cold reactive collisions in which the kinetic energies and quantum states of the colliding particles may be controlled to a high degree, a multistage Zeeman decelerator for neutral radicals has recently been developed in our laboratory\footnote N. Vanhaecke, U. Meier, M. Andrist, B.H. Meier, and F. Merkt, Phys. Rev. A , 75 031402 (2007). S. D. Hogan, D. Sprecher, M. Andrist, N. Vanhaecke, and F. Merkt, Phys. Rev. A , 76, 023412 (2007).. This instrument relies on the same concept of phase stability as employed in charged particle accelerators\footnote V. Veksler, J. Phys. (USSR) , 9, 153 (1945). E. M. McMillan, Phys. Rev. , 68, 143 (1945). and multistage Stark decelerators\footnote H. L. Bethlem, G. Berden, and G. Meijer, Phys. Rev. Lett. , 83, 1558 (1999). and can be used to decelerate cold samples of radicals in supersonic beams.
The results of a recent series of experiments in which we have decelerated ground state H and D atoms will be presented. In these experiments magnetic fields of 1-2~T were pulsed in each coil for tens of microseconds, with rise and fall times shorter than 5~µs. We have studied the influence Majorana spin-flip transitions on the deceleration process and made systematic studies of the deceleration behavior as a function of the phase angle, the magnitude of the pulsed magnetic fields and the initial velocity of the beam. Finally we have shown that a supersonic beam of H atoms initially moving at 435~m/s can be stopped and reflected at the end of a 12-stage decelerator.