The preliminary results of fast neutron flux measurements in the DULB   laboratory at Baksan
  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. 
J.N. Abdurashitov, V.N. Gavrin, A.V. Kalikhov, A.A. Shikhin,   V.E.Yants, O.S. Zaborskaya (Institute for Nuclear Research, M...