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The Pad Chamber Numbering Scheme

Each pad / readout channel consists of 9 individual copper cathode rectangles called pixels, organized in a pattern to optimize position resolution and noise immunity.
   The indices for each pad is given by the z and wire coordinates of the central pixel.

The z and wire coordinate system within each module. Note: the padx range refers to a half PC1 sub sector. For a half PC2/3 sector (i.e. one side) the range is [0,39].

The pad numbering scheme.

The cell in the upper left corner (z = 0, wire = 0) thus contains three pixels with pad indices (1,-1), (0,0) and (-1,1). There are no cells at z = -1 or wire = -1.

NOTE: The scheme is shown from the motherboard side, as the electronics see it.

The local coordinate systems
The following pictures show the local coordinate systems. NOTE: Only the PC3W motherboards are facing the IP. In the PC1 and PC2/3E chambers the pixelboards are facing the IP.


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