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Is the beamspot needed in hit selection?

Is the beamspot needed in hit selection?. On the way, some other stuff… pseudo-tuning the c 2 selection comparing against reco tracks The beam spot & hit finding…. All plots are August data, 180886 through trigsim (Thanks, Wendy). All STT fits. d x, hit-STT fit , m m.

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Is the beamspot needed in hit selection?

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  1. Is the beamspot neededin hit selection? • On the way, some other stuff… • pseudo-tuning the c2 selection • comparing against reco tracks • The beam spot & hit finding… All plots are August data, 180886 through trigsim (Thanks, Wendy)

  2. All STT fits dx, hit-STT fit, mm What’s the correct c2 selection? data? (heuristic) track <-> hits central peak = good tracks rest = junk (+multiple scat?) Vary c2 selection method may have pT bias… Why? eliminate junk fits keep efficiency Initially: single muon MC idealized situation “good” fits junk

  3. All tracks, bkg sub. Loose c2 Tight c2 For now: c2 < 2 22 + (8/pT)2 Vary c2 Requirement dx, hit-STT fit, mm

  4. Need a “standard” if possible Previous studies used MC as standard For data, beyond internal consistency use RECO Make some comparisons using old MC code, with RECO tracks instead of MCKINE good reco track n(SMT) > 2/8 layers n(CFT) > 13 layers c2/ndof < 4 pT > 1.0 GeV 20 events, 93 total fits RECO->STT 2D track match c2 50 20 events, 35 good fits c2 too good. Must be same hits in fits ! 20 20 recoed events before crash in tupler

  5. Reco track STT road >2 hits STT fit 13 y, cm 1.0 1.9 1.1 5.0 1.6 1.6 1.1 4.3 pT = 1.4 GeV (reco) x, cm

  6. ? Zoomed in (tight c2)

  7. Reco track STT road >2 hits STT fit 2.1 1.1 2.0 1.6 4.8 2.1 3.0 1.3

  8. ?

  9. c2, good tracks Beam spot f, degrees Do we need to use beam spot when selecting hits… Some evidence in c2 vs. phi Study using trigsim tuples before effort of implementing in integer form. In principle fastest means of getting answer But some problems on the way…

  10. Some verification? 1. Use same hits as in original (trigsim) fit (Wendy) Found CFT A-phi taken from old code. After fixing, get “practically perfect” results. 2. Use hits-in-road from trigsim (SttR branch) to verify that I can select hits properly. only 75% (re)select same hits… Why? 3. Reselect hits using same list, but beam spot for center 53% reselect same hits 4. Eventually try using offset road as well 44% reselect same hits

  11. Road center results • Method # of good Amplitude of • (prev. page) fits c2 vs. f • 1 4693 0.26 • 2 5328 0.21 • 3 4342 0.30 Huh? • 4 4462 0.29 Taken at face value, there is something in the algorithm which degrades when moving away from (0,0). Keep working…

  12. Summary • More to do on main topic: road center and hit selection • Cannot exactly reproduce test cases • Result seems counter-intuitive • On the way did • 0th order good track selection (drop hits cut?) • Good matches between reco and STT ! • NB: opposite sign(b) convention: RECO vs. STT • Just the first step, lots left to do, but good news • Poor match cases, efficiency, fakes, … all remain to do

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