Chapter 9 Maintenance
Mini-Switch LB 471
9.4.4 Plateau Measurement
Errors in the crystal-multiplier combination are indicated by a plat-
eau that is either too short or too steep. A plateau measurement is
used to check the function of the detector. The result of a plateau
measurement is presented in a table or a graph.
The radiation conditions have to be constant as long as the plat-
eau measurement is running! This means that the level must re-
main below the limit level during measurement. The radiation
channel of the shielding must be open in order to utilize the max-
imum radiation field for the measurement.
A plateau is the flat section in the characteristic curve and is typi-
cally approx. 200 V long.
The crystal-multiplier combination or the complete detector has to
be replaced if:
the plateau is shorter than 50 V
the count rate changes by more than 5% per 100 V high volt-
age.
The plateau measurement can be started via a software function.
See software manual.
Figure 47:
Typical plateau curve
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