Proposal for a new pad division

1. Proposal for a new pad division Daniel

2. Current layout • Not projective in R across various layers in depth • Size of pads vary a lot inside a detector • Some pads have a funny shape • Size at high η isn’t significantly smaller than at low η • Very difficult to describe such an arrangement by an algorithm

3. Proposed new layout : 1- R segmentation • Projective in R : define an abstract grid for the 1st layer of the pivot plane, starting at lowest R of active layer, with a pitch of 80 mm. The intersection of this grid with layers 1 and 3 of both pivot and confirmation wedges sets the boundaries. • Same for layers 2 and 4, staggered by 40 mm • Much easier to describe by an algorithm

4. Proposed new layout : 2- φsegmentation • Phi boundaries are no longer “vertical”, but follow the trapeze shape. • Define the (integer) number of φ divisions ineach unit (e.g. 4) • Pads are staggered half-half, but in the -1/4, +1/4 scheme: • -2.0 -1.25 -.25 .75 2.0 • -2.0 -.75 .25 1.25 2.0 • Ratio of smallest to largest pad in a row: 3/5

5. All in all …. • Projective in R across various layers • Size of pads vary for 3 to 5 • No pad has a funny shape • At high eta, size is smaller than at low high L good for rate balance • “Simple” to describe by an algorithm

6. What next ? • Go over the “details” and fine tune table of dead areas, etc… etc… • Repeat the optimization of φ-division in view of η dependence of rate. • Produce automatically all drawings and make sure that no bad surprise arises