Determination of potassium in feldspars by beta counting using a GM multicounter system

A gas flow multicounter system developed at Risoe National laboratory for low-level beta counting applications was adopted for measuring potassium in feldspars extracted from archaeological and geological materials, in connection with TL dating work. A guard counter reduces the background by using an anticoincidence technique. Calibration was accomplished by measuring KCl and a feldspar standard. A potassium content of 1% yields a net beta count rate (background subtracted) of about 40 c.p.h; the background is around 15 c.p.h. The precision in repeated measurements is better than 2% and the estimated accuracy is about 3%. (author)