A method of production of radioactive standards applied in science, nuclear medicine and industry to calibration of instruments for radioactivity measurement has been presented. This multimethodical system for the absolute activity measurement consists of four parallel multiparametric coincidences and anticoincidence methods. Such a system assures a mutual verification of the methods used, decreases an uncertainty of the result, and helps to notice a malfunction of the equipment.
A scheme of the four-fold scintillation head comprising a liquid scintillator and two NaI(TI) counters together with its electronic circuit was given. A description of the absolute mrasurement methods elaborated, i.e. the 4p(LS)-g coincidence with two g-parameter and 4p(LS)-g-anticoincidence with two g-parameter is given. It has been proved that the presented multimethodical system of activity measurement makes it possible to produce standards of a new generation, viz. the standards which are reliable and highly accurate. In the experimental part, an application of the multimethodical system to activity measurements of five radionuclides (¹⁹²Ir, ²⁰⁴Tl, ⁶⁰Co, ²⁰³Hg and ¹³³Ba) with different decay schemes was demonstrated. The combined standard uncertainties for these radionuclides were calculated.