  A method is proposed to use of the mixture of Uran oxide and non-active
matrix (e.g., NaCl) and also potassium and lanthanum for determining
Ge-detector efficiencies. The preparations containing of known amouts of the U
or K, or La were measured by means of the Ge-detector, which a efficiency curve
has been obtained through the reference solutions of 241Am, 109Cd, 57Co, 139Ce,
137Cs, 60Co. Results the measurements were compared the activities of the
preparations calculated from mass of 235U, 238U, 138La, 40K in the samples, its
natural abundance, half lives and intensities of gamma lines. Discrepancy of
the activities in the energy range between 163 and 1461 keV does not exeed 7 %.
For correct comparison of the activities the coefficients {\omega} were
calculated, which took into consideration a varied sorption of gamma-rays in
water and in mixture of the Uran oxide and matrix.
