Provisional shielding for laboratory measurements of low level activities with semiconductor detectors

The application of semiconductor spectrometry in low level counting requires the use of detector shielding to weaken the effect of ambient sources of ionizing radiation. The design is described of provisional shields of lead bricks for three different types of high-purity Ge detectors by Canberra. In the configuration of six polyethylene vessels around the detector with a total sample volume of 1200 ml, minimal detectable activities were determined of selected radionuclides. The experiment showed that the determination of minimal detectable activity in this configuration shows sufficient values for determining the content of natural and artificial radionuclides for monitoring samples from the environment of nuclear power plants. (Z.M.). 5 figs., 3 tabs., 2 refs