ECOTEST SPECTRA MKS-11GN Operating Manual page 17

graphical color display (GCD), battery (B), and thermal detector
(TD).
GDUh consists of the detector of CsI(Tl) scintillator type with
silicon photomultiplier and amplifier, while NDU – of the detector of
LiI(Eu) scintillator type with the silicon photomultiplier and
amplifier. GDUl is represented as a Geiger-Muller counter.
The principle of operation of the detecting unit is based on the
transformation of scintillations caused by gamma or neutron
radiation in the scintillator into the voltage pulses in the
semiconductor photomultiplier. These pulses are emanated to the
input of the amplifier where they are intensified and come to the
output as pulses of positive polarity. The number of these pulses is
proportional to gamma or neutron radiation DER, and the amplitude
– to the energy.
For high temperature stability of the detectors with silicon
photomultiplier, DPM constantly compensates temperature by
measuring exact values of temperature at the detectors, and precisely
adjusting the bias voltage.
DPM processes the pulse flow coming from the outputs of
GDUh, GDUl, NDU, and calculates the value of gamma radiation
DER, which corresponds to this flow considering the multichannel
amplitude analysis, and the pulse count rate from GDUh, GDUl, and
NDU.
Depending on the operating mode of the device, the GCD shows
the readings of DER, flux intensity, intensity flow histogram,
statistical error for gamma and neutron channels.
If DER exceeds 50 µSv/h by gamma channel, GDUh is
automatically turned off, and the DER value is calculated from
GDUl that runs continuously.
The DPM consists of the nonvolatile memory, which stores the
event log files, saved gamma spectra, and a library of spectra.
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