Results on substituting the NaI by a Ge detector in a simple shadow shield whole body counter

Since 1976 a whole body counter (WBC) has been used at the Rossendorf Research Centre for measuring the internal contamination of workers. The HP Ge detector (n-type, efficiency 43%) was substituted for a 3 x 3 NaI(Tl) detector. From the simple substitution, without any modification of the WBC construction the following improvements have been achieved: (1) Clear nuclide identification; (2) Decrease of the lower limit of detection from about 100 Bq to about 60 Bq, or reduction of the measuring time from 2000 s to 1000 s; (3) Faster availability of the analysis results by using a commercially available spectrum analysis software package; and (4) Simpler calibration of the WBC due to the use of a multiline emitter