FIELD: geology. SUBSTANCE: method provides for irradiation of investigation medium by flux of gamma-quanta and for registration of scattered gamma radiation (Ni) with energy 0.1-1.0 MeV at one or several distances from source. Volumetric density is determined by relation of intensities of specified energies by graduation dependence ρ = f(Ni). Effective atomic number Zeff of medium is found in addition by registration of soft component of scattered gamma radiation in energy region less than 200 keV. Finding of Zeff is conducted by method of selective gamma logging. Then correlation relation between value Zeff and parameters k/2 Σ FiZi/PiAi, characterizing change of element with atomic number Zi and atomic weight Ai. is established. Calibration of devices in units of electron density ρvol= f(Ni). is performed on standard density samples. Volumetric density is calculated by relationship ρ = ρvol/k. e/K. EFFECT: expanded application field, improved authenticity of investigations. 2 dwg, 2 tbl
