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Diagram explanations


Radioactivity measurement

1. Data measured by the detector

Diagram - measurement data of the detector

Total gamma count pulses N in 3600 sec.

Wedekind's quotient (ratio of pulses below/above 900keV)
  Natural radionuclides have gamma lines both above and below 900 keV. By contrast, artificial radionuclides produced in nuclear accidents mostly are in the energy range below 900 keV. Applying the quotient, it is possible to filter the artificial radiation from a mixture of natural and artificial radiation.

2. Computet proportion of artificial radioactive gamma radiation RAK

Diagram - calculated artificial activity

The RAK value is computed from current measurement data and the zero effect mean values , eliminating natural activity inputs (e.g. Rn-222 daughter nuclides during rainfalls) and filtering out the artificial nuclides.

3. Daily spectra

Diagram - daily spectra

In case of elevated radioactivity levels, the spectra provide additional information on the nuclides concerned and their activity contributions based on the computation of peak areas. The daily spectra are plotted on top of each other, which allows an easy identification of changes from the preceding day.
The following peaks are well visible in normal operation:

Gamma lines of the spectra



242 keV


295 keV


352 keV


609 keV


662 keV






Besides the natural energy lines, Cs-137 is clearly identifiable as an artificial nuclide from the 1986 Tchernobyl fallout in the Baltic Sea.


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If you have any additional questions, please e-mail Dr. Jürgen Herrmann or phone +49 40 3190 - 3325


More information on the subject:
MARNET monitoring system

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 © 2016 Bundesamt für Seeschifffahrt und Hydrographie Last Update: Apr 19, 2013 6:01:27 PM  
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