BTeV Muon Trigger Algorithm: Timing: R&D: Overview 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.

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

How to trigger on muon tracks: In each octant: For a given view (R,U,V, or S): Examine correlations between hit tubes in all 3 stations

Distance-To-Plane Cut R2 R0 R1 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 Distance to “plane” s=1.5 tubes good m events R2 R0 R1 Strategy: Cut on closest distance to this plane for each crossing/octant/view.

Determining track charge is simple ! All we need to do is look at R2 vs R0. R0 R2 = 1.275*R0 -125

Crude kinematic measurements are 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 as NO, 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” to identify 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!