  A novel traveling-wave Zeeman decelerator based on a double-helix coil
geometry capable of decelerating paramagnetic molecules with high efficiency is
presented. Moving magnetic traps are generated by applying time-dependent
currents through the decelerator coils. Paramagnetic molecules in
low-field-seeking Zeeman states are confined inside the moving traps which are
decelerated to lower forward velocities. As a prototypical example, we
demonstrate the deceleration of OH radicals from an initial velocity of 445 m/s
down to various final velocities. The experimental results are analyzed and
numerically reproduced with the help of trajectory simulations confirming the
phase-space stability and efficiency of the deceleration of the molecules in
the new device.
