In order to provide the necessary accuracy of the anode centring in the tube, each one of the 128 PSD has to be mounted on the mechanical support with 2 precise flanges.

All PSD, including spares, have been radiographied by X-rays. These radiographies will help to set up a relationship between possible failures and mechanical defects: for example, several PSDs show a misalignment between the spring guide and the tube wall up to 0.5 mm; this misalignment creates the potential danger of anode breaking when the High Voltage is ON.

The fragility of the PSD is now considered as the major remaining risk in the project. Moving the detector when the High voltage is ON would probably destroy some PSDs. A circuit is being developed to discharge the 2 decoupling capacitors (68 nF) of each PSD before any displacment of the detector.

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