GAMMA-SPECTROMETRY TECHNIQUE Russian patent published in 2000 - IPC

FIELD: applied nuclear geophysics, geology, geochemistry, and metallurgy. SUBSTANCE: gamma- spectrometry technique includes recording of natural or induced gamma- radiation by means of detectors, measuring intensity of spectral fluxes within preset energy spaces of each spectrum whose boundaries are determined by position of reference γ-line in first-detector spectrum. First detector is enclosed by screen that functions to absorb gamma-rays and lighting up X- rays. γ-spectra from each of detectors are recorded simultaneously in two energy ranges; to this end, threshold selection and signal amplification at gain factors of K₁ and K₂ are conducted; then channel numbers of gamma- radiation peaks of naturally radioactive nuclides are found in full γ-spectra, and energy scales of first-detector n₁-spectrum are calculated in first approximation using position of chamber number , maximum of X-ray peak E₁, and its energy γ- from definite formula. Minimal-error peak is found in main high-energy spectrum and approximate values of energy are calculated from definite formula using energy scale value. Minimal-error energy peak Emini

is identified using definite expressions. Second approximation for energy scale and calibration equation are calculated using found energy and chamber number of energy peak Emini and nmini and position of X-ray maximum ((E₁, n₁)) from definite expressions; energy value is identified for all other peaks in tight component spectrum of first detector, and true scale is calculated for all peaks of tight-component spectrum; for the purpose, calibration equation is derived using method of least squares. Energy scales are determined for remaining detectors in first approximation by position of Emini and nmini peaks in them; then calibration equations are found for each detector, approximate values of energy are calculated and identified for remaining peaks of each spectrum, final calibration equations and scales of detectors are found, then gain factors are corrected by definite times. EFFECT: improved measurement accuracy. 3 cl, 2 dwg, 1 tbl