The schematic for the wiring within one Faraday cage (one super-layer) at the HV end of a chamber is shown in Figure 2. The HV input is a shielded cable connector with the shield isolated from chamber ground by 1k, to break possible ground loops. A site for a parallel capacitor is provided because there is anecdotal evidence of HV system oscillations with an isolated ground scheme.
The fuse pulser input is a twin-axial cable which runs from a point up to to 15m from the chamber to a patch panel at a convenient location on the detector. The shield is again isolated by a 1k resistor from chamber ground. The signal conductor carries a large pulse (up to a few x 100V) to blow the fuse to tubes with broken a wire. The ground conductor carries the return current from the pulse generator. In all normal modes of chamber operation the fuse pulser input cable is disconnected at the patch panel.
It should be noted that the pulser cable signal line will float to a value close to the chamber operating voltage during normal operation.
![\begin{figure}
\center
\includegraphics [width=6in]{chamber.eps}\end{figure}](img4.gif)