4. Turn the LB 134 on. The software identifies the connected
β-γ-probe and sets the measurement mode accordingly.
5. If necessary, run a test measurement using a suitable test
source.
7.9.7 Practical Hints for Operation and Measurement
Operation with LB 134
The measurement of Tritium with the LB 134 and the connected
Tritium probe is carried out in the same manner as the contam-
ination measurement described above. Probe and calibration
factors are set such that only Tritium activities are determined
and displayed.
Measuring flat, horizontal areas
The counter tube LB 1239 with the entire open window length,
i.e. without the aperture plate, is used for measuring flat areas.
In this case the window opening must always face down and be
completely covered by the surface being measured to rule out
any unrestrained leaking out of the counting gases from parts of
the window opening. Please move the counter tube slowly
when scanning the surface.
Measuring irregular areas, clothing, finger tips, wipe
tests
For these measurements the aperture plate is placed onto the
probe. This reduces the effective area but allows monitoring of
critical areas for Tritium contamination. The aperture plate
should be used when interference is caused by possible elec-
tromagnetic charges on surfaces when the window area is fully
opened (too high or irregular count rates). After use, the probe
must be re-placed immediately into the holder on the trolley
console to shut off the gas flow.
If you don't use the instrument for a longer period of time,
close the valve of the P10 gas cylinder!
7.9.8 Performance Check
The regular performance check that is required by the German
Radiological Protection Act can be carried out using any beta-
emitting radionuclide, for example, a Sr-90 source. Simply place
the Tritium probe on the respective source. Due to the window-
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