• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
Pixel rf
 

Pixel rf

on

  • 645 views

excelente presentación

excelente presentación

Statistics

Views

Total Views
645
Views on SlideShare
644
Embed Views
1

Actions

Likes
0
Downloads
2
Comments
0

1 Embed 1

http://medicalunsa.blogspot.com 1

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment
  • bb Separation is 0-2  => b }  doesn’t indicate region for other b p T of b products is peaked at low values (? => use ID full-scan
  • Histogram for signal events Open histo : all combinations Filled : “best” : hatched : correct. cross-hatched - incorrect

Pixel rf Pixel rf Presentation Transcript

  • B-Physics Trigger Working Group Status Report http://hepunx.rl.ac.uk/atlasuk/simulation/level2/meetings/AweekFeb01/ Bphys210201.ppt Bphys210201.pdf Bphys210201.ps John Baines
    • Contents:
    • B-trigger selections at LVL2 and EF
    • EF rates, status at end 2000
    • Progress:
      • Tighter cuts for D s selection
      • J/  rate v. p T threshold
      • Example of rates with tighter cuts
      • Robustness studies
    • Future Work
    • Summary
  • Example B-Physics Trigger Menu
    • Level 2 : Confirm muon
    • ID full-scan require additionally:
      • Second  p T > 3-5 GeV or
      • electron p T > 5 GeV or
      • Reconstruct characteristic decay products e.g.:
        • e  e  pair, J/   ee  invariant mass window
        • 3 hadrons,  0 (KK) and D s (KK  ) mass
        • 2 hadrons, B d (  ) mass window
    • Level 1 : muon p T > 6 GeV
    • EF: Re-do ID recon. using offline-type algorithms:
    • Apply tighter cuts to J/   ee  D s (KK  ), B d (  )
    • Apply cuts to select J/     LVL2  and  -e triggers) 
    • Use offline-type cuts for rare decay channels (accepted
    • by LVL2  trigger).
     bb eX B d (J/  (  )K 0 )  bb  X B d (J/  (ee)K o )  bb  X B d (J/  (ee)K o ) B d     B d J/  (  )(K/K*) B s J/  (  )  B  B K 0 *  , etc.  b  0 J/  (  ) B c J/  (  ) 
      • Better track resolution Tighter Mass cuts
      • Vertex fit cuts on  2 , decay length,
      • angular cuts based on event topology
    B  B K 0 *  , etc. B s D s  B s D s a 1 D s  o  ,  o K  K  To be studied further.
  • B-physics Trigger Rates Status at TDAQ Week Nov 2000
    • Note:
    • Events with direct J/  (  ) and J/  (ee) are also needed, however these can be pre-scaled.
    • Rates subject to uncertainties in cross-sections & muon rates.
    • Physics programme and trigger menu will evolve with time up to and after LHC switch-on.
    • EF rate estimates are based on offline code. In particular K/  rejection at EF (and LVL2) has to be
    • demonstrated with algorithms suitable for EF (LVL2).
    • Work is continuing on EF selections for B d,s - >  X  channels.
    Level-2  6 +  5  6 + e5  6 + B(  )  6 + D s (  (KK)    6 + J/  (ee) Total (B-physics triggers) 100 Hz 50 Hz 50 Hz 150 Hz 200 Hz 550 Hz muon p T >6 Level-1 23 kHz muon p T >6 (ID+muon) Level-2 5 kHz EF B d,s - >  (X) (  p T >6) J/  - >   6 + B(  )  6 + D s (  (KK)    6 + J/  (ee) Total (B-physics triggers) small 10 Hz 5 Hz 25 Hz 20 Hz 60 Hz muon p T >6 (ID+muon) EF 5 kHz
  • B d     Trigger Efficiency for B  events with pile-up (L = 10 33 cm -2 s -1 ): 78% : B  events, p T (  ,  ) > 4 GeV 93% : B  events selected offline 0.93% : Background B  X events Level-2 rate ~50 Hz for 5 kHz  6 EF selection reduces rate to ~5 Hz
    • Event Filter Selection:
    • Tighter mass cut
    • Vertex fit cuts :
      •  2 / N d.o.f. < 8,
      • L xy > 100  m,
      •  xy < 5
    • Level-2 selection:
    • Tracks separated from trigger  by  R  > 0.2
    • p T > 3.9 GeV
    o
    • Two opposite sign tracks with:
    • p T + p T > 10 GeV
    •  z 0 < 2 cm
    • 4.3 < M(  ) < 6.3 GeV
    + -  xy L xy Decay Vertex 10 15 20 25 30 35 40 45 50 p T of B d (GeV) B d p T spectrum both  p T >4 GeV 100 80 60 40 20 0 Level-2 Efficiency (%) x y LVL2 0 2 4 6 8 M(      (GeV) Signal Events + min. bias
  • D s  Trigger o
    • Level-2 Selection:
    • Tracks: p T > 1.4 GeV
    •  R  > 0.2 w.r.t. trigger 
    • EF Event Selection:
    • Tracks: p T > 1.5 GeV
    • Mass cuts :
    • M(KK) - M(  ) < 14 MeV
    • M(KK  ) - M(D s ) < 56 MeV
    •  vertex fit cuts:
    •  2 prob. >0.5%, L xy > 200  m
    • D s vertex fit :
    •  2 prob. >0.5%, L xy > 200  m
    • Two opp. sign tracks satisfying:
    • M(KK) - M(  ) < 17 MeV (~3  trigger )
    • Third track with:
    • M(KK  ) - M(D s ) < 74 MeV (~3  trigger )
    New selection cuts by Innsbruck
    • Level-2 Efficiencies for
    • B s D s (  (KK))  events with pile-up
    • (L = 10 33 cm -2 s -1 ):
    • 58% : Signal events with
    • p T (  ,  and K) > 1.5 GeV
    • 63% : Signal events selected offline
    • 3% : Background B  X
    • events
    • Level-2 Trigger rate ~150 Hz
    • for 5 kHz  6
    • EF selection reduces rate to
      • 21 Hz 4  offline mass cuts
      • 17 Hz 3.5  offline mass cuts
      • 13 Hz 3  offline mass cuts
      • for 5 kHz  6
      •  offline (  ) = 3.4 MeV
      •  offline ( D s ) = 14 MeV
  • Effect of higher muon p T threshold: D s (KK)  trigger Study by Innsbruck of impact of raising muon p T threshold on D s (KK)  trigger Signal efficiency falls of fairly rapidly, more rapidly than background.
  • J/  e  e  Trigger
    • Event Filter Selection:
    • Tighter mass cuts
    • Vertex fit cuts :
      •  2 / N d.o.f. < 8,
      • L xy > 220  m,
      •  xy < 40
    • Two opposite-sign e tracks with:
    • p T + p T > 4 GeV
    • |  | < 1.4, |  z 0 | < 2 cm
    • cos(  ee ) > 0.2
    • 2 < M(ee) < 3.5 GeV
    + -
    • Level-2 Selection:
    • Tracks: p T > 0.5 GeV
    • Identified as electrons by TRT
    Level-2 Efficiencies for B d J/  (ee)K s events with pile-up (L = 10 33 cm -2 s -1 ): 44% : Signal events with p T (e,e) > 1.5 GeV 57% : Events selected offline 4% : Background B  X events Level-2 Trigger rate ~200 Hz for 5 kHz  6 EF selection reduces rate to ~20 Hz o Signal Events + Min. Bias 0 1 2 3 4 5 M(ee) (GeV) LVL2
  • Effect of electron p T Threshold 25 20 15 10 5 0 Rate (Hz) Signal Efficiency (%) Efficiency for B d - > J/  (ee) K 0 (  ) Rate for B - >  X + pile-up for 5 kHz  6 rate p T cut (GeV) p T cut (GeV) 0.5 1.0 1.5 2.0 2.5 3.0
    • Study by Moscow of effect of raising
    • p T threshold for e in J/  (ee) trigger
    • Further rate reduction, with some loss of
    • physics, e.g. :
    • Raising p T cut from 0.5 GeV to 0.8 GeV
    • gives
      • Rate reduced from 17 Hz to 8 Hz
      • 4% efficiency loss for B d - > J/  (ee) K 0
    100 80 60 40 20 0 0.5 1.0 1.5 2.0 2.5 3.0
  • B-physics Trigger Rates - Example of tighter cuts muon p T >6 (ID+muon) EF 5 kHz
    • Note:
    • Tightening D s and  mass cut gives negligible signal loss provided the same mass resolution can be achieved at the EF as offline => need to assess impact of calibration, availability of survey info and impact of any speed-up of algorithms c.f. offline. Similarly for other “offline-type” selections.
    small 10 Hz 5 Hz 13 Hz 10 Hz 38 Hz 5 kHz Notes: Assuming offline-type selection Estimate (conservative?) (Signal ~2 Hz, Bg about same) Rounded up from 3 Hz from Flora Mass cuts tightened to 3  offline add  transverse decay length cut.. p T threshold raised to 0.8 GeV => 4% signal loss. EF B d,s - >  (X) (  p T >6) J/  - >   6 + B(  )  6 + D s (  (KK)    6 + J/  (ee) Total (B-physics triggers) small 10 Hz 5 Hz 25 Hz 20 Hz 60 Hz
  • LVL2 Robustness Studies Misalignment (  m) Misalignment (  m) 1 10 100 1000 1 10 100 1000 90 80 70 60 50 40 Efficiency (%)  D s (MeV) 60 40 20 Effect of Pixel Barrel Misalignment on B(  ) trigger Effect of SCT barrel Misalignment on D s (  (KK)  ) trigger Fraction of Hits/Spacepoints deleted 60 50 40 30 Efficiency (%) 0.001 0.01 0.1 Effect of inefficiency on D s (  (KK)  ) trigger Pixel Barrel 15 30 Endcap 50 100 Limits on R  precision (  m) for signal loss <2% <5% SCT Barrel 60 100 Endcap 80 100
  • Future Work - Robustness
    • Robustness Studies:
    • Extend LVL2 robustness studies to J/  channel including TRT
    • Compare robustness of TRT-guided c.f. pixel-guided reconstruction for J/ 
    • Look at EF selection, expected to be more sensitive than LVL2 due to:
      • vertex fit quality cuts
      • transverse decay length cuts
      • tighter mass cuts
      • .
    Easter 2001 Moscow End 2001?? Who?? Easter 2001 Moscow
  • Future Work - LVL2
    • LVL2 Studies:
    • Repeat B-trigger measurements including muon simulation (previously used Kine).
    • Effect of New layouts:
      • - evaluate effect of latest ID layout (Insertable pixel layout).
    • LVL2 Algorithm Development :
    • Scan of pixels+SCT (more robust than pixel-scan) two techniques:
    • - based on pixel-scan : Genova
    • - based on hit filtering algorithm + kalman fitter : Nikos
    • Vertex reconstruction at LVL2 - Nikos?
    • Reproduce cTrig functionality in new framework
    • Add new functionality in new framework:
      •  and e reconstruction in ID RoI
    Need new data-sets => Spring 2002?? Time-scales set by PESA s/w group - September 2001 Autumn 2001?? All Need muon code and new data-sets. Probably use new framework => Mid 2002 Autumn 2002? End 2001?
  • Future Work - EF Selection
    • EF Selections :
    • Investigate EF selections for B - >  X channels
    • Check compatibility of cuts with offline selections, particularly background estimations, systematic bias etc.
    • Check effects of layout changes
    • Timing measurements for B-selections, development of algorithms suitable for EF (ID, Muon, Calorimeter reconstruction).
    Pythia studies : Easter 2001 September 2001?? Need new data-sets => Spring 2002?? Need all algorithms in new framework Mid 2002?? Moscow, Innsbruck? Full simulation - needs data-sets => End 2001?? Moscow (Nikolai) B Physics WG Who??
  • Datasets
    • Datasets with ID ‘insertable’ layout, modular TRT, true solenoid B-field:
    • Single particle datasets for tests
    • Whole detector (incl. muons):
      • Signal datasets :
        •  6 + B  ,
        •  6 + B D s  B D s a 1 ,
        •  6 + B J/  (ee),
        • B J/  (  6,  ),
        • B  (X)
      • Background : B  X
      • Datasets for studies with  and e in LVL2 RoI from ID:
        •  6 + B J/  (e5e)
        • e5 + B J/  (  6,  )
        • B J/  (  6,  )
    Easter 2001? Autumn 2001?? End 2001??
  • B-trigger Workplan 2002 2001 Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Pythia studies EF: B  (X) full sim. studies EF Timing Timing for B selection J/  , TRT Robustness EF Robustness studies Algorithm develop. Pixel scan incl. SCT LVL2 vertexing Studies in New f-w cTrig Functionality New s/w Reconstruct e in RoI from ID Reconstruct  in RoI from ID repr. TP results verify TP - new layout add LVL1 + LVL2 mu TP results + mu Full B-menu ID sngl prt Dataset Prd. New layout Sig. & bg all det.
  • Summary
    • D s (  (KK)  ) trigger: tighter EF cuts studied => ~halving of rate.
    • Effect of raising muon p T thresholds studied, but signal efficiency falls rapidly
    • J/  (ee) trigger: raising e p T threshold studied, can ~halve rate for 4% signal loss.
    • Robustness studies:
      • LVL2 Trigger robust w.r.t. SCT misalignment.
      • Pixel R  misalignment limit: 15  m (barrel).
      • Trigger robust w.r.t. SCT inefficiency.
      • Main concern is impact of dead pixels on pixel-scan efficiency, but a new more robust algorithm is being developed.
      • Studies will be extended to the J/y(ee) trigger and TRT
      • Studies will be extended to EF if someone can be found for this work.
    • Algorithm development is continuing. Vertex finding at LVL2 will be investigated.
    • Studies started for EF selection for B  (X), initially at the particle level.
    • Future work will be focussed on:
      • new data-sets with the whole detector and updated ID layout.
      • additional functionality in the new s/w framework leading to a simulation of the complete B-physics trigger menu ~end 2002.