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BTeV Muon Trigger

BTeV Muon Trigger. Mats Selen Aug 25, 2003. Algorithm: Overview Efficiency & Rejection Timing: Results of running DSP based trigger code on a large sample of Monte Carlo events. R&D: What's Next. R. U. V. S. Muon system has 3 stations with 4 views each (R,U,V,S).

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BTeV Muon Trigger

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  1. BTeV Muon Trigger Mats Selen Aug 25, 2003 • Algorithm: • Overview • Efficiency & Rejection • Timing: • Results of running DSP based trigger code on a large sample of Monte Carlo events. • R&D: • What's Next.

  2. R U V S Muon system has 3 stations with 4 views each (R,U,V,S)

  3. How to triggeron muon tracks: R2 R1 R0 m In each octant:For a given view (R,U,V, or S):Examine correlations between hit tubes in all 3 stations

  4. R2 R1 R0 Distance to “plane” Distance-To-Plane Cut Muon tracks line on a simple plane: R2 = 27.69 - 1.26*R0 + 2.20*R1(R0,R1,R2) in raw “tube numbers” • muon tracks • uds events s=1.5 tubes good mevents R2 R0 R1 Strategy: Cut on closest distance to this plane for each crossing/octant/view.

  5. m- • m+ Determiningtrack chargeis simple ! R2 R1 R0 R2 All we need to do is look at R2 vs R0. R0 R2 = 1.275*R0 -125

  6. R2 Crude kinematicmeasurementsare also possible: Ptotal • Not exploited further in this study. • Can (for example) imagine calculating a crude dimuon mass. R0 R2 Sin2q R0

  7. Di-Muon Trigger: m+ m- Look for tracks by octant. Look for tracks in one or more views (R,U,V or S). Tag each octant asNO, POS or NEG A “dimuon” event has at least one POS and one NEG octant

  8. Example Trigger Study • Conditions for these plots: • Use all 384 tubes/view(also studied using only the outermost 352, 320 tubes) “2/4” and “3/4” means that 2 and 3 planes respectively, out of the possible 4, were needed to pass “D-Cut” toidentify a track in an octant.

  9. D-cut = 1 <N> = 2 Dimuon Trigger Efficiency vs. Tube Hit Efficiency(this example is for Cut = 1) There is a large parameter space that yields e > 60% and Rej > 500

  10. Performance vs. <N> (average number of min-bias events/crossing) “3/4”, e = 97% Even for <N> = 5 we can get a rejection of ~ 500 with an efficiency of ~ 60%.

  11. Size & Speed • Work done by UIUC ECE grad student John Cassel: • Ported RTES file-I/O code to the muon trigger. • Implement “clock-cycle” counting technique for timing tests. • Re-wrote & optimized PC code for DSP (i.e. made it run fast !! ) • DSP results for efficiency & rejection agree with PC! TMS320C6711

  12. Executable Code:91.3 kBytes <Time> = 760 ticks(~6 ms @ 133 MHz) <Time> = 1686 ticks(~13 ms @ 133 MHz) Unless something changes,speed is not an issue.

  13. Muon Trigger Status • Work to date is a “existence proof”. • Trigger algorithm in good shape. • Speed adequate. • System will evolve as design continues

  14. BTeV Future You tell us!

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