  One of the main sources of a background in underground physics experiments
(such as the investigation of solar neutrino flux, neutrino oscillations,
neutrinoless double beta decay, and the search for annual and daily Cold Dark
Matter particle flux modulation) are fast neutrons originating from the
surrounding rocks. The measurements of fast neutron flux in the new DULB
Laboratory situated at a depth of 4900 m w.e. in the Baksan Neutrino
Observatory have been performed. The relative neutron shielding properties of
several commonly available natural materials were investigated too. The
preliminary results obtained with a high-sensitive fast neutron spectrometer at
the level of sensitivity of about 10^(-7) neutron/ (cm^2 sec) are presented and
discussed.
