SAPHYMO MiniTRACE CSDF - Figure 6: Display in Cps Mean Mode

Instruction Manual for MiniTRACE CSDF
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Page 12 08/2012
pancake detector. With the lid open you can measure α-, β- and γ-radiation. This detector is
very sensitive and protected by a grid.
Note
: All given measurement values are gross values. This means that background
values are NOT subtracted.
Basically you should do contamination measurements (i.e. on surfaces) in 2 steps:
1. Measurement with lid closed to determine the γ-contamination
2. Measurement with lid open to determine the α-, β- and γ-contamination
To determine the β-component another step is necessary:
3. Measurement with lid open and a sheet of paper on the detector. Subtract the value
from measurement 3 from measurement 1; the result contains the β-contamination.
To determine the α-component another step is necessary:
Measurement with lid open and a sheet of paper on the detector. Subtract the value from
the result without and with paper and you will get the α-contamination.
To determine the α- and β-components another step is necessary:
Subtract the value from measurement 2 from measurement 1; result contains the α- and
β–contamination.
Note: For a higher precision of the measurement result the radiation background has
to be measured first and then subtracted from the final result.
α–radiation can be shielded with a piece of paper.
β-radiation is almost completely shielded by closing the lid.
2.4.3.4 Mean value of the count rate in cps
Select the “CMEAN menu” by using the mode button. Once “CMEAN” is displayed, wait 3
seconds; the menu will start automatically. For further details see Figure 3.
With this menu you can check the contamination of a surface, for example. If the count rate
is “stable” in your environment and you would like to determine the count rate more precisely
you can use this menu. The longer the measurement, the higher the accuracy. This mode
does NOT react to rapid changes in the radiation level.
The value is given in counts per second (cps). In the top left corner of the display, the
statistical uncertainty is given. By default a statistical uncertainty of 3 sigma is calculated.
You can change the sigma value using the MiniTRACE software. For more details see the
additional software manual.
With the lid closed only γ-radiation is measured. If you open the protective lid (material:
aluminum, thickness: 1 mm) you will see the Geiger-Mueller pancake detector. With the lid
open, you can measure α-, β-, and γ-radiation. This detector is very sensitive and protected
by a grid. See also 2.4.3.3.
Figure 6: Display in cps mean mode