Main emission lines: 1460keV, 1760keV, 2614keV
The main contribution to the natural radiation background is made by potassium-40, as well as the daughter products of the decay of uranium and thorium. The natural background is characterized by all lines of their daughter isotopes. The total hump in the beginning is the sum of many gamma lines. This energy can vary greatly, so it is not usually considered in the analysis.