  We report on storage of Very Cold Neutrons (VCN) in a trap with walls
containing powder of diamond nanoparticles. The efficient VCN reflection is
provided by multiple diffusive elastic scattering of VCN at single
nanoparticles in powder. The VCN storage times are sufficiently long for
accumulating large density of neutrons with complete VCN energy range of up to
a few times 10(-4) eV. Methods for further improvements of VCN storage times
are discussed.
