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To change the layer length in the BPix you want to change the number of modules per half rod in the “Barrel PXB” section of PixelTechnicalProposal2014.cfg:
Barrel PXB { numLayers 4 numModules 4 <---------------- this what you want to change innerRadius 29 outerRadius 161 width 22 <------------ this is the module length along x (local x) length 71 <-------------- this is the module length along z (local y) ..... }
One module is always located centrally so that the number of modules in a rod is always an odd number. For example, numModules 3 will result in 7 modules per rod.
You can actually change the length of a layer (including innermost and outermost layers) by specifying the number of modules to use/rod for this layer:
Barrel PXB { numLayers 4 numModules 4 innerRadius 29 outerRadius 161 width 22 length 71 ... Layer 1 { radiusMode fixed placeRadiusHint 29 numModules 3 } ... }
Here are some numbers after making the following changes: - extend layer 1 and 2 by one module - bring layer 2 closer to beam pipe (58 mm) - move layer 3 and 4 out (120 mm, 180 mm) - change disc 1 to make 3 discs of 1 ring each (1 at 265 mm, 1 at 285 mm, 1 at 335 mm)
1 GeV layout 02 TDR C I F VF WF C I F VF WF pT 1.84731 2.88889 3.91328 3.84539 11769598 2.34579 3.62749 3.65583 3.90297 11769598 d 0.00608 0.0077 0.01112 0.0151 39535.403 0.00625 0.00816 0.0112 0.01446 39535.4027 phi 0.00209 0.00292 0.00412 0.00534 10849.57674 0.00224 0.00321 0.00415 0.00482 10849.5765 z0 0.00748 0.01362 0.03911 0.11751 0.25247 0.00723 0.01342 0.03911 0.11134 0.24704