Possibility of increasing the accuracy and efficiency of continuous nuclear-physical measurements

Abstract

In general, the useful (target) information in a recorded energy distribu,ion of the radiation can be present in several energy intervals of the spectrum of the radiation. The working intervals of the measurements are usually sections of the spectrum where useful information is present in a "pure" form or together with noise (background). The noise can be determined (known) and taken into account when the results are processed. So, in the case of -/-testing of rocks for the content of natural radioactive elements, -/-rays with energy greater than 250-300 keV are recorded, whose flux density is directly proportional to the mass fraction of radioactive elements in the rocks, since it is represented mainly by the primary and singlyscattered radiation of the elements. The radiation flux density in the low-energy range of the spectrum of natural -/-radiation (20-250 keV, mainly multiply-scattered radiation) also depends on the mass fraction of radioactive elements in the rocks, but this dependence is parametrically related with the effective atomic number of the emitting--absorbing medium in the region of the detector, whose uncontrollable variations over the well shaft can lead to a large error in the determination of the mass fraction of the radioactive elements. At the same time, the flux density of useful (relative to the mass fraction) information in the interval 20-250 keV is much higher than in the interval above 250 keV, especially when the radiation is detected with small scintillation detectors which possess a high sensivity to the low-energy part of the radiation spectrum. This information would greatly decrease the statistical errors in determining the natural radioactive elements, as happens in measurements of the total radiation specmam in media with constant effective atomic number. On this basis, the problem of statistical grouping of the useful information in the signal fluxes in detection of ionizing particles can be formulated in the most general form as follows. Useful information is present in two statistically independent signal fluxes (in two nonoverlapping intervals of the radiation spectrum). In the first signal flux (conventionally, the main flux)