On the preparation of efficiency calibration standards for gamma-ray spectrometers

A procedure for preparation of low-activity efficiency calibration standards in different geometries and having different densities for gamma-ray spectrometers has been develpped. Natural organic and inorganic materials are used as matrices. The densities of the matrices used vary from 0.4 to 1.5 g/cm3. The activity distribution homogeneity in the matrix after preparation and after using them for 9 months was studied. The matrix stability to settling down and selfgrinding in the process of continued usage is examined. The standards have been prepared using certified mixed-nuclide gamma-ray standard solutions, containing 241Am, 109Cd, 139Ce, 57Co, 60Co, 137Cs, 203Hg, 113Sn, 85Sr and 88Y and mono-nuclide solution containing 210Pb from EUROSTANDARD, traceable to the Czech Metrological Institute.