We present a first experimental demonstration of a new method to extract a
well-collimated beam of ultra-cold neutrons (UCN) from a storage vessel.
Neutrons with too large divergence are not removed from the beam by an
absorbing collimation, but a diffuse or semidiffuse channel with high Fermi
potential reflects them back into the vessel. This avoids unnecessary losses
and keeps the storage time high, which may be beneficial when the vessel is
part of a UCN source with long buildup time of a high UCN density