FIELD: physics.
SUBSTANCE: apparatus for determining characteristics of underground formations surrounding a borehole has an radiation source effective to generate a first and a second time- and spatially separated X-ray source, wherein the first and second X-ray sources are designed to irradiate underground formations at first and second entrance angles which are different in time and space; one or more X-ray detectors capable of generating a first and a second signal indicating intensity of the first and second X-ray sources returning from the underground formations to one or more X-ray detectors; and a housing accommodating the radiation source and one more X-ray detectors.
EFFECT: reduction of the total number of detectors used while maintaining accuracy and reliability of formation density measurements.
15 cl, 6 dwg
