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BTeV Level 1 Muon Trigger Algorithm

BTeV Level 1 Muon Trigger Algorithm. Michael J. Haney 16 May 2001 www.hep.uiuc.edu/engin/btev/reports/16may01.ppt (and .pdf). Numbers. 2 arms, 8 octants each octant-arm treated independently 16-fold (geographic) symmetry 3 stations (1,2,3) , 4 views each (R,U,V,R)

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BTeV Level 1 Muon Trigger Algorithm

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  1. BTeV Level 1Muon Trigger Algorithm Michael J. Haney 16 May 2001 www.hep.uiuc.edu/engin/btev/reports/16may01.ppt (and .pdf)

  2. Numbers • 2 arms, 8 octants • each octant-arm treated independently • 16-fold (geographic) symmetry • 3 stations (1,2,3) , 4 views each (R,U,V,R) • 13 (12?) planks, 32 tubes each • double-layer (16+16, offset)

  3. Assumptions • complete octant-arm data delivered to board • implies 16 “boards” • can be fewer if density permits (1/N) • may be necessary… (see last slide) • complete crossing data • no mixing • must finish current before beginning next

  4. (soft) Assumptions • complete view data • must finish current before beginning next • data delivered radially inward • outer to inner • These assumptions are not critical,but if they are easy for the Muon front end,they will reduce/eliminate sorting...

  5. Algorithm (FPGA) • compress adjacent tube hits • can be done serially (on-the-fly) if the soft assumptions are met… • need to understand how to handlemany-adjacent hits...

  6. Algorithm (FPGA/DSP) • AND/OR (selectable) R,R views • reduce to single RR “view” • working radially inward,form valid RR2-U2 pairs(fixed table size => outer bias) • look-up V2‘s from RRU2‘s;form RRUV2’s • and RRV2’s and UV2’s, etc.as space/time permits... U 2 V 2 3 3 4 4 6 R 8 10

  7. Algorithm (DSP) • window-search RR3’sbased on RRUV2’s • look-up U3’s and V3’sfrom RRUV2RR3’s • look-up RR1’s, U1’s, V1’sfrom RRUV2RRUV3’s • declare RRUV1RRUV2RRUV3’s(and various lessers) as “tracks” • calculate c2’s (?)

  8. Algorithm Notes • radially-inward processing • biased in favor of higher PT • implications on front end readout (order) • fixed table sizes • accommodates “wall of fire” near beam pipe • octant-arm specific • 16-fold symmetry in hardware • no inter-octant communications

  9. Algorithm Notes (continued) • combinatoric explosion - suppressed • RRU2’s require O(N2) • “look-up” steps require O(M) • window search? O(M) to O(M2) • could be fully implemented inthe Pixel Trigger DSP Farm • but compression/table-building may be donein (Pixel Trigger?) FPGAs

  10. Loose Ends • pure 16-fold geographic symmetryproduces 16 “opinions” per crossingfor the Global L1 to consider • may need to collapse 16:1 at FPGA-DSP boundary • same as Pixel Trigger 31:1 • Even if we can use the same FPGAs,will Muon front end look likePixel front end (number of spigots)?

  11. Highways • The Muon Trigger has 16-fold geographic symmetry • (8-fold per arm) • 8-fold highways imply 128-fold symmetry • may need need several “folds” per FPGA boardjust to keep the system size reasonable

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