1. 2 Dec 1998F Harris LHCb Trigger Meeting L0 Trigger - ‘Real Estate’ Considerations Current thinking for the size and location of L0 trigger electronics, and the required links, for the various options

2. 2 Dec 1998F Harris LHCb Trigger Meeting Overview of possible locations for electronics, and associated cable lengths For each option summary of size and location of electronics, and the associated link requirements Summary and Conclusions

3. 2 Dec 1998F Harris LHCb Trigger Meeting Possible locations for FE Electronics (D Lacarrere) On Detector –attached to detector mechanical structure e.g Cal and Muons (? space) Balconies both sides of UX85 cavern –Vertex side (10*2.5m.,5m. High) 10 racks –Muon Side (10*2.5m.,5m. High) 10(+5) racks –TOTAL RACKS on balconies 25 racks Counting Rooms behind radiation shield(access with LHC beam) –platform A (Delphi) 2 levels + top(*) 18*2 = 36 racks –platform B (Delphi) 3 levels + top(*) 28*3 = 84 racks –platform C (Delphi) 2 levels + top(*) 18*2 = 36 racks top(*) gas racks,cooling systems, electrical power converters –+ Platform B bis 3 levels 28*3= 84 racks –TOTAL RACKS behind shield 240 racks

4. 2 Dec 1998F Harris LHCb Trigger Meeting First estimates for Cable Lengths from detectors to FE electronics on the balconies( D Lacarrere) Sub-detector Distance to FE crate (m.) – Min Max –Vertex 12 20 –Rich1 10 20 –Rich2 20(35) 25(40) –Ecal 20(35) 25(40) –Hcal 15(30) 20(35) –Muon 15(30) 20(35) These estimates reflect the 1st iteration (+- 1 m.)

5. 2 Dec 1998F Harris LHCb Trigger Meeting L0 Options Calorimeter Triggers –Orsay (O Callot) –Bologna(M Bruschi) –3D(D Crosetto,S Conetti) Muon Trigger –Marseille(R le Gac) –3D(D Crosetto,B Cox) –Gatchina ideas(V Golovtsov) - to be reviewed

6. 2 Dec 1998F Harris LHCb Trigger Meeting Calorimeter Trigger - Orsay proposal (O Callot) Boards and crates for trigger electronics –Trigger logic for each channel embedded in FE-card (16 channels/card). (25 crates of FE-logic for ECAL and 25 for PreShower. 7 crates for HCAL). –60 Summary Cards for ECAL, PreShower, HCAL embedded in FE-crates –ECAL Selection Crate –HCAL Selection Crate Location of trigger electronics –Channel logic and Summary Cards embedded in FE-logic on-detector (top and bottom) –Selection Crates on balcony (cable distance 15-30m.) Links for trigger electronics –PreShower to ECAL (500) ? in the same crate or nearby crate (backplane or v. short links) –Pad to Preshower 250 Gbit links 10 m.? –ECAL to HCAL 100 Gbit links 10m. ? –Links to Selection crates 125 Gbit links up to 30m.

7. 2 Dec 1998F Harris LHCb Trigger Meeting Calorimeter Trigger - Bologna proposal (M Bruschi) Boards and crates for trigger electronics –L0 Board handles 4*4 or 6*6 Ecal channels 2*2 or 3*3 Hcal channels 25 or 49 PS channels 50 or 98 PAD channels –Number of boards and crates 4*4 388 Boards 26 Crates(6U) 6*6 180 Boards 12 crates(9U) ******* preferred as of 2 Dec 1998 Location of Trigger electronics –First thinking is to place on top and bottom of Ecal mechanical structure Links –6*6 33/board ~6 K links (1080 ‘short’, 2700 ‘medium’, 2160 ‘long’) –testing National DS90CR283/284 (28 bit transmission at 66 MHz on 10m. Twisted pair) OK at 10m., problems at 15 m. ? Useof repeaters

8. 2 Dec 1998F Harris LHCb Trigger Meeting Calorimeter Trigger - 3D Proposal (D Crosetto,S Conetti) Assumptions –TP 3*3 algorithm (18 steps conservative), 2*2 would be less –For electron trigger - 8 bit Ecal, 1 preshower bit, 2 Pad bits gives rate to PE of 440 MHz –For Hadron trigger - 8 Ecal + 8 Hcal + 4 gives rate of 800 MHz Size of 3D electronics (using current technology) –Electron Trigger requires 54 K PEs Can fit 16 PE ASIC in 5*6 mm. ( 80 such chips on 9U board gives 1280 PEs/board) 16 boards in a crate. Therefore 54 K PEs Can fit in 3 crates –Hadron Trigger requires 13.5 K PEs, Can fit in 1 crate

9. 2 Dec 1998F Harris LHCb Trigger Meeting Calorimeter Trigger- 3D Proposal Location and Links (6000 + 1500) –‘Near’ configuration on balcony(limited access) Distance up to 30 m. Link technologies being investigated.( see below), and connectivity to boards –‘Far’ configuration behind the shield (access no problem) Distance around 60 m. Looking at developments in Digital Television (currently can get 10 bit parallel at 40 MHz on twisted pair up to 120 m. at a cost of 90$). Must check on error rates etc.

10. 2 Dec 1998F Harris LHCb Trigger Meeting Calorimeter Trigger - 3D Proposal COSTS –Electron/photon trigger 3840 ASICS (16 PE/ASIC) @ 80$/ASIC 307 K$ 48 boards @ 2000$/board 96 K$ 3 crates @5000$/crate 15 K$ Cables –‘near’ solution (6000*$30) 180 K$ –‘far’ solution (6000*$90) 540 K$(**) System Host + Miscellaneous 60 K$ TOTAL –‘Near’ solution 658 K$ –‘Far’ solution 1018 K$ (**) ** expect considerable cost decreases in long links (Digital Television Technology) ?? –Hadron Trigger Cost about 1/3 of electron/photon

11. 2 Dec 1998F Harris LHCb Trigger Meeting L0 Muon Trigger - Marseille proposal (R le Gac) Location of electronics –FEBI (Front End Board Interface) 7 crates on edge of detector (these hopefully will be part of the FE electronics design) –FIP and DMP processors 2/3 crates on balcony –Monitoring and debugging 1 crate on balcony Links from FE electronics to trigger processors (FIP and DMP) –100-350 optical links, length 15-30 m. –1 parallel Cu link ~30 m. to L0 decision box Comments (much brainstorming going on) –Number of optical links depends on algorithm (being evaluated) –Integration of FEBIs with muon FE electronics (links etc.) ?? –Could one put L0 decision box and TTC processor on balcony?

12. 2 Dec 1998F Harris LHCb Trigger Meeting Muon Trigger - 3D proposal(D Crosetto,B Cox) Assumptions –Input to system is 45 K bits at 40 MHz –TP algorithm - 1.3K PEs in each of 3 layers + a small second stage - need 5K Pes maximum Size of system –Need 312 ASICs each of 16 PEs –Can fit in 5 9U boards Single crate system Location and links (4500) –Near (on balcony) –Far (behind wall) –Link technology being investigated, and connectivity into boards

13. 2 Dec 1998F Harris LHCb Trigger Meeting Overview comments for L0 proposals All proposals assume ‘normal’ electronics i.e. no special rad-hard (? rad- tolerant) All assume TTC and L0 decision box behind radiation shield (why not on balcony to reduce latency?) Variety of assumptions on type and cost of links. This needs expert survey and ‘normalisation’ - need experiment policy (report by next LHCb week) All (except 3D ‘far’ proposal) place trigger electronics in ‘no-access’ region(s) All proposals evolving - more detail in next LHCb week (with costings)

14. 2 Dec 1998F Harris LHCb Trigger Meeting Summary (rough) of System characteristics Calorimeter triggers –Option Crates Location Links Comments –3D 3+1 Balcony ( 6000 + 1500)*30 m. ?Links and connectivity? –‘HERA-B’ 12 On det ~6000 (2160*10m.+) “ + electronics location –Orsay 2 Balcony ~1000 (475*10m+) Some trigger logic in FE Muon trigger –Option Crates Location Links Comments –3D 1 Balcony 4500*30m. ?Links and connectivity –Marseille 2/3 Balcony (100-350)*30m. ? Integration with FE

15. 2 Dec 1998F Harris LHCb Trigger Meeting Conclusions All proposals will change in the light of new information on the location of electronics, and on link technology. This should proceed in a coherent way (dissemination of information + working meetings) At the next LHCb week there should be a coherent overview of available link technologies (performance,cost,error rates etc.) meeting our requirements. (make best efforts to summarise these a.s.a.p) We must pursue the issue of radiation and electronics. Groups should be given guidance on the timescale of months