  We demonstrate a 1-D velocity selection technique which relies on combining
magnetic and optical potentials. We have selected atom clouds with temperatures
as low as 2.9% of the initial temperature, with an efficiency of 1%. The
efficiency (percentage of atoms selected) of the technique can vary as slowly
as the square root of the final temperature. In addition to selecting the
coldest atoms from a cloud, this technique imparts a sharp cut-off in the
velocity distribution. The cold selected atoms are confined in a small well,
spatially separated from higher energy atoms. Such a non-thermal distribution
may be useful for atom optics experiments, such as studies of atom tunneling.
