Stabilization of spectrometers energy scale by gamma reference point in sampling radioactive ores

The most acceptable gamma reference for determining the U (from radium) and Th in mixed U-Th ores is the isotope 137Cs, which gives good apparatus stability and a rather low ''seeding'' of the operating energy window. Displacement of the energy scale as a result of distortion of the 137Cs reference photopeak in the superposition of the U and Th ore gamma spectra is no greater than 1% if Nsub(Cs)/Nsub(v(RA)) >=1.5-2 (Nsub(Cs) is the count rate with the same window width in the photopeak of the 0.609-MeV energy line in the apparatus spectrum of a uranium ore)