BTe V Muon Trigger Mats Selen Aug 25

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

Muon system has 3 stations with 4 views each (R, U, V, S) M. Selen, DOE Visit, 2003 R U V S

How to trigger on muon tracks: R 2 R 1 R 0 m In each octant: For a given view (R, U, V, or S): Examine correlations between hit tubes in all 3 stations M. Selen, DOE Visit, 2003

Distance-To-Plane Cut Muon tracks line on a simple plane: R 2 = 27. 69 - 1. 26*R 0 + 2. 20*R 1 (R 0, R 1, R 2) in raw “tube numbers” R 2 R 0 • muon tracks • uds events R 1 s=1. 5 tubes good m events Distance to “plane” R 2 R 1 R 0 Strategy: Cut on closest distance to this plane for each crossing/octant/view. M. Selen, DOE Visit, 2003

• m+ Determining track charge is simple ! R 2 R 1 R 0 R 2 All we need to do is look at R 2 vs R 0. R 2 = 1. 275*R 0 -125 M. Selen, DOE Visit, 2003 R 0

R 2 Crude kinematic measurements are also possible: Ptotal R 0 R 2 • Can (for example) imagine calculating a crude dimuon mass. Sin 2 q R 0 M. Selen, DOE Visit, 2003 • Not exploited further in this study.

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 M. Selen, DOE Visit, 2003

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. M. Selen, DOE Visit, 2003

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 M. Selen, DOE Visit, 2003

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%. M. Selen, DOE Visit, 2003

Size & Speed • Work done by UIUC ECE grad student John Cassel: w w 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! TMS 320 C 6711 M. Selen, DOE Visit, 2003

<Time> = 760 ticks (~6 ms @ 133 MHz) Executable Code: 91. 3 k. Bytes <Time> = 1686 ticks (~13 ms @ 133 MHz) Unless something changes, speed is not an issue. M. Selen, DOE Visit, 2003

Muon Trigger Status • Work to date is a “existence proof”. w Trigger algorithm in good shape. w Speed adequate. • System will evolve as design continues M. Selen, DOE Visit, 2003

BTe. V Future You tell us! M. Selen, DOE Visit, 2003