5. Contamination Measurements LB 124 Scint
38
For measurements according to § 44 of the German Radiation
Protection Ordinance the averaging area may be up to 300 cm².
The measurement area of the LB124 Scint is 118 mm x
145 mm (171 cm²) at a transmission of 80 %.
For contaminations with an extent of less than 100 cm², the av-
eraging takes place automatically according to the above-
mentioned calibration conditions. A contamination of, for exam-
ple, 10 Bq/cm² with an extent of only 50 cm² will accordingly be
displayed as 5 Bq/cm² (referred to 100 cm²).
If, however, the extent of the contamination is larger than 100
cm², the monitor will overvalue it: It will indicate 10 Bq/cm², dis-
tributed over 150 cm², as 15 Bq/cm².
5.4 Exceeding of Threshold Values
Any exceeding of user-defined threshold values is indicated on
the display next to the measured value by the message “Alarm”
and the type of radiation (α or βγ). In addition, an alarm signal is
actuated (visually as a flashing LED, acoustically as a brief
alarm sound or as vibration), if preset (see System Menu: Pa-
rameter->Alarm, chapter 6.8.6). Alarm will be indicated in any
case, regardless of the measurement mode you are in.
Figure 18: Exceeding of threshold values
The display shown below appears if the entrance window is
damaged (light gets inside the counting chamber) or if the count
rate range is exceeded. In this case, turn the device off, check
for possible contamination and the entrance window for leaks. If
necessary, replace the window foil (see chapter 7.2).
Figure 19: Error message if range is exceeded
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