At X-ray radiometric sampling of ores in natural occurrence or ore mass in transport tanks variable geometric factor is a serious interference.

The construction of modern theory of gamma- and neutron methods of nuclear geophysics should be based on the description of photon and neutron fields in heterogeneous media, reflecting the real structural features of ores.

The most important characteristics of the scattered -radiation field include: the position of the inversion region, the magnitude of the saturated volume, and the depth. There are numerous experimental data and individual calculations on these or other field parameters ...

X-ray spectral determination of light elements is notoriously difficult due to the low fluorescence yield, X-ray absorption on the path from sample to detector, and insufficient resolution of the commonly used proportional counters ...

The concept of effective atomic number Z_ef of rocks and ores follows from the idea of equivalence of γ-quantum properties of media of different material composition and is of fundamental importance for the development of γ-γ-methods of nuclear geophysics.

Significant volumes of drilling for prospecting and exploration of copper-nickel ores within the Pechenga and Alla-Akka-Yarva ore fields determine constant efforts aimed at improving well logging and increasing its efficiency. By the present time the issues of complexing of standard logging methods have been solved and the possibilities of both the complex as a whole and individual methods have been clarified in identifying the main types of rocks and ores.

When sampling ores by selective γ-γ-method the source of significant interferences are variable diameter and cavernosity of boreholes, irregularities of the sampled surface of walls in mine workings and variable density of rocks and ores. Inversion probes are proposed to eliminate these interferences. Theoretical and methodological issues related to the development and use of complex inversion probes of the selective u-method have not been addressed to date. The proposed paper represents a first step in this direction.

When studying the material composition and physical properties of ores (density, moisture) by nuclear geophysics methods, in most cases the result of physical field measurement depends on several parameters of the medium. Usually the problem is reduced to a one-parameter problem by selecting the appropriate conditions and observation technique. The possibilities of nuclear geophysics are significantly extended if the study of rocks and ores is considered as a multi-parameter problem, solving it by several conjugate measurements. There is, for example, simultaneous determination of ore density and content of heavy elements in them by two measurements of the u-field of Co-60 and Cs-137 sources under wide beam conditions; simultaneous determination of rock density and clay crust thickness by two measurements of scattered u-radiation with two different probe lengths. Similarly, the problem of sampling two-component mercury ores by integrated measurements of the y-field and thermal neutron field was solved. It is possible to formulate a number of three-parameter, four-parameter and similar problems, the solution of which is of great practical importance. An example of a three-parameter problem is the determination of the effective atomic number of the ore, its density and simultaneous consideration of the influence of the borehole diameter.

The development of the theory and practice of the γ-method requires the study of the depth of studies in specific conditions. Depth depends mainly on the type of the γ-radiation source, the density of the medium, the size of the probe (measuring unit) and its design, the position of the probe relative to the surface of the medium under study (the presence of the intermediate medium and its properties). Experimental study of depth studies mainly refers to the method of scattered γ-radiation ...

Determination of the volumetric weight of rocks and ores by gamma ray attenuation in them is performed in situ without disturbing the structure, natural moisture regime, etc. This automatically takes into account macro- and micro-cracking, cavernousness and other features of the structure and texture of rocks and ores. Determination of the volumetric weight of rocks and ores by attenuation of gamma rays has undoubted advantages over other methods: simplicity, high productivity and cost-effectiveness.

Testing of uranium ores in natural occurrence (boreholes and mine workings) is performed by gamma radiation. It is based on the proportional relationship between the intensity of radiation and the amount of radioactive elements in the ore. The coefficient of proportionality in this case is usually called the conversion coefficient. Since 93-98% of gamma-radiation of equilibrium uranium ore is caused by gamma-radiation of Ra226 and its decay products, the conversion factor is, in fact, the specific (per unit of content) intensity of the equilibrium spectrum of Ra226 registered by the detector at uniform distribution of gamma-emitters in an infinite medium (case of gamma logging) or in a half-space (case of gamma-testing in mine workings).