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Tracking Degradation

Summary of the Tracking Degradation SuperB workshop in Hawaii on April 21, 2005. Discusses the current operation condition of CDC, degradation of reconstruction efficiency, and electronics upgrade.

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Tracking Degradation

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  1. Tracking Degradation SuperB workshop in Hawaii April 21, 2005 K. Sumisawa (KEK) • current operation condition of CDC. • degradation of recon. efficiency in 3BG. • p+p- • J/yKs • D*D* • Summary.

  2. pedestal Recovery time Electronics Upgrade (Shaper/QT)(2004 Summer) deadtime Q • Installed in layer1-15 • Deadtime~800ns(~1/3) at layer 4-15 t0 t #16 – 49(2.2ms) #4 – 15 (0.8 ms)

  3. Example of J/yKs Event 1 x Bkg 3 x Bkg

  4. current condition of CDC Exp39 MuPair (run139 –220) (2004 autumn) data &MC • cut in track finding • loose drift timing cut width < 1.5ms • pulse height cut p.h. >~0.1MIP loose timing cut p.h. cut both cuts bkg occupancy ~0.8% 3 x bkg occup. =~2.4% track-asso.

  5. B→p+p- recon. Efficiency~high momentum tracking B→p+p- rec. eff (w/ geom. eff.) Single track eff. (square root of left value) MC study 1032/cm2/s MC study 1032/cm2/s For simplicity, assuming relation btw luminosity and BG level is linear: Current CDC config. 130x1032/cm2/s (x1), 260 (x2), 390 (x3) Old CDC config. 90x1032/cm2/s (x1), 450(x5) (reported@HL05(Nov.2004)) No degradation found in high momentum tracking eff. upto x3 BG of that in current operation condition.

  6. analysis code : actually used in physics analysis J/yKs(p+p-) recon. eff. check why we have this degradation.

  7. 1 x BKG 3 x BKG 10.2 MeV 9.2 MeV J/y 2.4 MeV 2.7 MeV Ks 7.1 MeV 7.9 MeV B tail components increase in 3BG

  8. check using J/yKs mass cuts for B, J/y, and Ks are only used. 3BG : eff. loss = 10.2% (1BG : eff. = 52.3%) updated T0 recon. narrow window of drift time. new readout electronics for 2 more layers. eff. loss = 7.3 % (+2.9% gain) use ideal T0 new readout electronics for all layers eff. loss = 6.7 % (+0.6% gain) this gain may be obtained by further updated T0 recon. eff. loss = 4.2 % (+2.9% gain)

  9. effect of track quality • Which effect is larger, track-finding eff. loss or track quality loss ?  Both are large; need to reduce both. • modify finder (now studying) • reject bad hits more effectively. (We start this study) mm pp both both+mass 1x bg 3x bg 3x bg + updates

  10. test a new track-finder for events with lost tracks. It can recover >~half of lost events. We still need time to develop new finder.

  11. example of D*+D*- events 1 x Bkg 3 x Bkg

  12. D*+D*- (both D*(K3p)ps) high multiplicity case loose mass for D0,D*-,and B0 cut are only required. case2 3BG : eff. loss = 32.9% (1BG : eff. = 4.050.14%, 3BG : eff. = 2.720.11%) case1 updated T0 recon. narrow window of drift time. new readout electronics for 2 more layers. case3 eff. loss = 18.7 % (+14.2% gain) new readout electronics for all layers case4 eff. loss = 12.1 % (+6.6% gain)

  13. case1 (1BG) D*D* mass for each cases case2 case3 case4

  14. Summary • for p+p-, no degradation in 3BG. • for J/yKs • Eff. loss (J/yKs)=10.2  7.3% with some updates. • Another 2.6% gain will be obtained if new readout electronics are installed for all layers. • To recover the remaining ~6-7% events, we should improve track-quality as well as finding eff. • It seems the new finder can recover > ~half of lost events. But we need to study more. • We have to improve a fitter in the track-finder for more efficient bad hit rejection (=for better track-quality).  We expect eff. loss (J/yKs) ~ few% soon. • for D*+D*- • Eff. loss (D*+D*-)=32.9%  18.7% with some updates. • tighter timing cuts are effective. • new readout electronics for all layers are also effective (+6.6%gain).

  15. backup

  16. case2 case3

  17. case3 case4

  18. condition of MC study • No L0 sim. • No L4/HadronB req. • Minor bug fix in CDC dead time (Fig) • Same random no.s both for 1 x and 3 x bkg. • event generation, detector simulation: common • 1 x bkg. overlay: common (Fig)  easy to compare results event-by-event.  easy to see small effects (less affected by stat. fluctuation). • A few updates in codes other than track-finder/fitter. • New track-finder. #16 – 49(2.2us) #4 – 15 (0.8 ms)

  19. B→D*(Dps)p recon. Efficiency~slow p tracking B→D*p- rec. eff (w/ geom. eff.) MC study Single track eff. (left value divided by Dp eff.) 1032/cm2/s MC study 1032/cm2/s Since new curl finder and less deadtime S/QT readout are installed in inner 15 layers, slow p reconstruction eff. gets better. For slow p tracking, CDC+SVD2 tracking is scheduled to improve efficiency and resolution.

  20. Results of Eff. Loss, Recovery

  21. J/y(mm)Ks by me Simple cuts: L4 & HadronB -60 < M(mm) - M(J/y) < 36 MeV |M(pp) - M(Ks)| < 16 MeV |M(J/yKs) – M(B)| < 40 MeV J/y(ll)Ks by Miyabayashi (+me) He applied the analysis code actually used in physics analysis Result.; J/yKs(p+p-)

  22. selection of D*D* o generated events B0->D*+D*-; both D*->(K3pi)pi 20000 events o cuts - 17 < theta < 150deg. is required for each decay particle at event generation level (for speed up) - no L4 or HadronBJ cut - mass cuts D-mass cut : nominal +-20 MeV D*-D mass diff cut: nominal +- 5 MeV B0 mass cut : nominal +-45 MeV

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