Advanced Level 1 Muon Trigger Algorithm for BTeV by Michael J. Haney
This presentation outlines the Level 1 Muon Trigger Algorithm designed for the BTeV experiment. It details a sophisticated framework that addresses processing challenges and utilizes 16-fold geographic symmetry to manage data across 2 arms and 8 octants. The algorithm effectively compresses adjacent tube hits and implements effective pairing mechanisms for track identification. Assumptions about data deliverability and processing order are discussed, emphasizing the efficiency of radial inward data handling. Key algorithmic strategies include window searches and look-up pairs optimization to balance computational needs while ensuring data integrity.
Advanced Level 1 Muon Trigger Algorithm for BTeV by Michael J. Haney
E N D
Presentation Transcript
BTeV Level 1Muon 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) • 13 (12?) planks, 32 tubes each • double-layer (16+16, offset)
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
(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...
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...
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
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 (?)
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
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
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)?
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
