BERTHOLD TECHNOLOGIES LB 480, User Manual

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02.2017
Menu Structure Volume 3
2.9
Quick Start, Step 2
1 Time Constant
The time constant smoothes the output signal. Statistical fluctua-
tions, as well as level fluctuations due to the process, e.g. by agita-
tors, are smoothed. A time constant of 20 s is usually reasonable.
2 Nuclide

Enter here the isotope (nuclide) that is used in your source:
• Co-60
• Cs-137
• USER DEFINED
This entry controls the automatic decay compensation. The correct
entry is also important in a single-point calibration and for gas den-
sity compensation. The isotope used is listed on the type plate of
the shielding and on your delivery documents. The item
USER
DEFINED allows you to use any isotope you want. In this case,
additional parameters are requested: Specify the half-life under
Half Life Time and the absorption coefficient at Absorption .
What happens when you have selected the wrong isotope?
As a result of the wrong decay compensation, you will get a deviat-
ing display only after several weeks or months, with the deviation
increasing over time. If you perform a calibration with the gas den-
sity compensation GDA, or a 1-point calibration, the wrong isotope
will also calculate wrong calibration data.
3 ReadIn Time

Here you can define the period of time over which the count
rate is to be read-in for each calibration point.
The statistical variation of the count rate is averaged over this time
period. The longer it is, the better the mean value. A time period of
30 s (default setting) is usually reasonable.