Absorption method for determination of pure beta-emitters in samples containing more than one beta-emitter

Absorption method is shown to be suitable for direct determination of pure β-emitting, isotopes in samples containing more than one β-emitter. This method consists of (1) measurement of the β-counting rate as a function of the thickness of the absorber placed in between the sample and the β-detector and (2) decomposition of the complex absorption curve by computation in order to obtain the contributions of the nuclides to the total counting rate one by one. The method is presented through two examples of its practical application in the field of environmental radioanalysis:⁹⁰Sr and¹⁴⁷Pm isotopes were determined in aerosol samples contaminated by Chernobyl radioactivity and in hot particles of Chernobyl origin using a simple end-window Geiger-Müller counter as a β-detector.