Method for calibrating a radiometric density measuring apparatus

Method for calibrating a radiometric apparatus for determining and/or monitoring density of a medium (6) located in a container (1), wherein a transmitting unit (3) and a receiving unit (4) are provided, wherein the transmitting unit (3) transmits radioactive radiation of a predetermined intensity and wherein the receiving unit (4) receives radioactive radiation transmitted by the transmitting unit (3) after passage through the medium (6), and wherein a control/evaluation unit (7) is provided, which determines density of the medium (6) located in the container (1) based on intensity measured by the receiving unit (4), wherein the method comprises method steps as follows:

• determining the mass attenuation coefficient μC of the empty container (1) with application of the half value thickness N/N0=0.5 of the radioactive radiation upon passage through the empty container (1) according to the formula:
• N/N0˜I/I0=e−μC·ρ1D, with μC:
• mass attenuation coefficient, ρ1:
• density of the material of the wall of the container, D:
• distance traveled by the radiation, or inner diameter of the container (1), I:
• intensity of the measured radiation, I0 intensity of the transmitted radiation, N measured counting rate, N0 counting rate of the transmitted radiation,
• determining the mass attenuation coefficient (μM) based on the measured intensity, or the counting rate, of the radioactive radiation after passage through the container (1), when a calibration medium of known density (ρ2) is located in the container (1),
• ascertaining the dependence of the linear absorption coefficient (p) on the geometric dimensions of the container (1) based on the two mass attenuation coefficients,
• calculating a calibration curve, which shows the dependence of the density of the medium on the count of measured radiation intensity after passage through the container (1).