A wholebody counter with semiconductor detectors for radiation protection measurements

At the Austrian Research Centre Seibersdorf a Wholebodycounter with semiconductor detectors was designed and installed. The measurement geometry is the 'Scan-Geometry'. Two high-purity germanium detectors (each 30% relative efficiency) are scanning across the person, one below and the other above the person. Both detectors are shielded with a lead-shield. The wall-thickness is between 2 and 4 cm. It is also possible to use additional lead-collimators in different shapes. Physical characteristics as longitudinal, transversal and vertical variations of efficiencies were measured. Calibration measurements were done with the BGA-Phantom in different sizes and lower limits of detection were calculated. This Wholebodycounter is very convenient for radiation protection measurements, although the shielded room where it is situated has not extremely good low-level conditions. (author)