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Principle of Operation of a DNX-Detector
A DNX detector is built up, in principle, like an electric plate-type capacitor. One uses the interaction of a gas for the detection of a photon or neutron. To the achievement of a sufficient response characzeristic for the measurement of higher energetic photons detectors must feature filling gases with enough big absorbing capacity. To the proof of neutrons the special gas fillings in which especially very ionising secondary particles are released are used. The incoming photon or neutron is absorbed by the gas in the detector. The effect which originates from the absorption is the local ionisation of the gas which leads to electrons and positive ions. If a tension is put itself on in parallel and in small distance to opposite electrodes, a homogeneous electric field is based between them.

Fig.1: Principle of Gas Amplifying

Fig.2: Assembling of DNX-1D-Detectors

Does a photon now steps in the airspace between the electrodes, so positive and negative load bearers are generated by a push with the gas molecules along his trajectory which are drawn by the oppositely loaded electrodes. The load push originating from it can be measured as an electric impulse. While in the plate-type capacitor, only the load bearers generated indirectly or directly contribute to the measurement, a strengthening effect which is based on the multiplication of these loads in the gas space is used in the proportional detector.

A primarily released electron generates with it an avalanche of secondary electrons, so that, in the end, a lot of bigger number in load bearers originates from a photon or a neutron than to the primarily ionisation corresponds. As a measuring signal only they will have caused practically, as a result of the gas strengthening to slightly movable electrons, the amusing impulses, used.

Therefore, proportional detectors serve predominantly for the impulse measurement and the proportionality allows a differentiation in kind and energy of the radiation between impulse height and primary ionisation. Ordinarily becomes by the installation beside each other of recumbent countable pipes, a proportional detector dimensional sensitive to place built up which can grasp the dispersion of photons or neutrons. A DNX-Detector unites the single countable pipes to a proportional countable pipe and connects the single cathodes by a delay line.

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