1. Proposal by the Numbers 3 Trigger layers (plus 2 “short” layers) provide full coverage to eta=??? in 15 degree sectors Hits collected in real time, sent off-detector on 5k-10k optical fibers at ~ 6 Gbit/sec All possible track equations for each sector evaluated in parallel using FPGAs in USC to produce ROI inputs for L1 Total of ~ 1000-2000 Virtex-6 class FPGAs could be used to build this using current technology

2. 40 mm  Z = 5 mm  Z = 1-2 mm Plane 1 Plane 2 Stack 2 Z +R  Readout chips 80 mm inner station 70mm mid/outer stations Z  100 mm  = 100  800 …50... : : ASIC Kapton Readout Cables Fiber Tx One Z-segment Kapton Cables ASIC Z pixel resolution Carbon fiber Rod support Plane 1 Plane 2 Stack 1 R-phi view of rod structure Some detector details

3. r=350 r=550 r=1100 4 rods / 15 o sector 2 rods 1 rod One 15 degree sector showing layout of “rods” (full-length layers) Doublet data rate estimate: 8x10 cm = 80 cm 2 2 particles / cm 2 from Monte Carlo estimate Thus 160 particles/BX 10x reduction due to 2-layer coincidences Thus 16 particles/BX per Z-segment of a rod 20 bits/hit 10 bits  6 bits Z 2 bits curvature (+/0/-) 2 spare bits 16 hits * 20 bits * 40MHz = 12.8 Gb/sec (2 fibers for inner station) Inner station Middle station Outer station

4. IP Layer 1 -- Inner station Layer 2 -- Middle station Layer 3 Layer 4 Layer 5 Layer 4 Projection Layer 3 Projection 21 Z segments 28 Z segments 10 Z segments Z R R-Z view of 1/4 of barrel showing Z segmentation Z-segments processed in groups of 7 One “Z-group” = 700 mm of rod Inner station - 3 Z-groups Layers 3, 4, 5 Outer Station Middle station - 4 Z-groups Outer station - 7 Z-groups Short layers 3,4 extend eta reach

5. x x x x x x x x x x Doublet (2-layer coincidence) Tracklet (4-layer coincidence with P T validation) Doublets formed by readout chips Tracklets may be formed either on-detector by ASIC, or in USC by the trigger processor. Processing for each Z-Segment of a Rod x x x x x x x x x x Tracklet (4-layer coincidence with P T validation) ASIC If ASIC sends doublets off-detector, then each station requires two optical fibers per Z-segment per sector to handle the data volume If ASIC forms tracklets, this volume is reduced by about 2X

6. Outer station divided into 12 sub-segments Routing logic sorts outputs from inner, middle layer rods to target output layer sub-segments using IP point and p T Outer layer divided into 12 sub-segments Tracks of > 2.4 GeV p T can traverse at most (2) 15 o sectors. Trigger logic must handle inputs from “home” sector plus n-1 and n+1 “home” sector sector n-1 sector n+1

7. 14 12 outputs To sector n+1 12 outputs to sector n-1 14 12 14 12 Inner Station Logic processes 3 Z-groups of 7 Z-segments each Middle Station Logic Processes 4 Z-groups of 7 Z-segments each Outer Station Logic Processes 7 Z-groups Of 7 Z-segments each 7 * 12 7 groups of 12 links from 7 Z-groups to 12 subsector processors 12 subsector processors Inputs from sector n+1 Inputs from sector n-1 Input: Doublets or Tracklets from detector Output: Track candidate found Trigger Processor for one sector in USC

8. Inner/Middle Station Logic Details 2 2 optical fibers From each Z-segment Total of 7 Z-segments Tracklet block converts doublets Into tracklets 12 Sorter block sorts tracklets using IP, pT into sub-sector of outer station Tracklet data sent to home sector, plus 2 neighbors 2 12 Tracklet data sent to home sector only Outer Station Logic Details