Berthold DUO XPERT LB 470RID, Руководство по эксплуатации

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LB 470RID Level 3 System Description
56925-1BA2 Rev.02, 05/2021
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measurements. This system distinguishes between the energies of the wanted and
unwanted radioactive isotopes and suppresses the effects of the unwanted radia-
tion. This represents a huge advantage in situations where frequent weld testing
is performed.
3.3.1 Scintillation Detectors
Every gamma absorbed in the scintillator material generates a light flash whose
intensity depends on the energy of the gamma radiation. The light pulses are con-
verted in the coupled photomultiplier into voltage pulses whose height is
proportional to the energy of the gamma which generated it.
The detector electronics compares the height of the measured voltage pulse to a
preset voltage, the measuring threshold. Only pulses of sufficient voltage (height)
to exceed the measuring threshold are counted by the evaluation electronics and
determine the measured pulse rate in the measuring channel (MC) and the level in
the container is calculated from the pulse rate in the measuring channel. To be
able to work with as low as possible radioactive source activities, the measuring
threshold is set so low that all radiation pulses are registered, and high enough
that the noise of the electronics cannot contribute to the measured pulse rate. The
height of the measuring threshold is a direct measure of the sensitivity of the meas-
uring system: The higher the measuring threshold, the higher is the source activity
required to reach the same count rate.