Development and Efficiency of the BTeV Muon Trigger System: Results and Future Directions
This paper presents the BTeV Muon Trigger development, focusing on the algorithm efficiency, rejection rates, and the performance of the DSP-based code applied to a large dataset of Monte Carlo events. The status of the trigger system is assessed, with emphasis on the muon trigger strategy that examines correlations between hit tubes across three stations and various views. The results indicate high efficiency and satisfactory rejection levels. Additionally, the future direction of the Muon Trigger system is outlined, highlighting ongoing developments and optimizations.
Development and Efficiency of the BTeV Muon Trigger System: Results and Future Directions
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Presentation Transcript
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)
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
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.
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
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
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
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.
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
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%.
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
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.
Muon Trigger Status • Work to date is a “existence proof”. • Trigger algorithm in good shape. • Speed adequate. • System will evolve as design continues
BTeV Future You tell us!
