Pixel rf

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  • bb Separation is 0-2  => b }  doesn’t indicate region for other b p T of b products is peaked at low values (<~10GeV) muon trigger min p T ~6 GeV Calorimeter trigger pT >? => use ID full-scan
  • Histogram for signal events Open histo : all combinations Filled : “best” : hatched : correct. cross-hatched - incorrect
  • Pixel rf

    1. 1. 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 <ul><li>Contents: </li></ul><ul><li>B-trigger selections at LVL2 and EF </li></ul><ul><li>EF rates, status at end 2000 </li></ul><ul><li>Progress: </li></ul><ul><ul><li>Tighter cuts for D s selection </li></ul></ul><ul><ul><li>J/  rate v. p T threshold </li></ul></ul><ul><ul><li>Example of rates with tighter cuts </li></ul></ul><ul><ul><li>Robustness studies </li></ul></ul><ul><li>Future Work </li></ul><ul><li>Summary </li></ul>
    2. 2. Example B-Physics Trigger Menu <ul><li>Level 2 : Confirm muon </li></ul><ul><li>ID full-scan require additionally: </li></ul><ul><ul><li>Second  p T > 3-5 GeV or </li></ul></ul><ul><ul><li>electron p T > 5 GeV or </li></ul></ul><ul><ul><li>Reconstruct characteristic decay products e.g.: </li></ul></ul><ul><ul><ul><li>e  e  pair, J/   ee  invariant mass window </li></ul></ul></ul><ul><ul><ul><li>3 hadrons,  0 (KK) and D s (KK  ) mass </li></ul></ul></ul><ul><ul><ul><li>2 hadrons, B d (  ) mass window </li></ul></ul></ul><ul><li>Level 1 : muon p T > 6 GeV </li></ul><ul><li>EF: Re-do ID recon. using offline-type algorithms: </li></ul><ul><li>Apply tighter cuts to J/   ee  D s (KK  ), B d (  ) </li></ul><ul><li>Apply cuts to select J/     LVL2  and  -e triggers)  </li></ul><ul><li>Use offline-type cuts for rare decay channels (accepted </li></ul><ul><li>by LVL2  trigger). </li></ul> 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/  (  )  <ul><ul><li>Better track resolution Tighter Mass cuts </li></ul></ul><ul><ul><li>Vertex fit cuts on  2 , decay length, </li></ul></ul><ul><ul><li>angular cuts based on event topology </li></ul></ul>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.
    3. 3. B-physics Trigger Rates Status at TDAQ Week Nov 2000 <ul><li>Note: </li></ul><ul><li>Events with direct J/  (  ) and J/  (ee) are also needed, however these can be pre-scaled. </li></ul><ul><li>Rates subject to uncertainties in cross-sections & muon rates. </li></ul><ul><li>Physics programme and trigger menu will evolve with time up to and after LHC switch-on. </li></ul><ul><li>EF rate estimates are based on offline code. In particular K/  rejection at EF (and LVL2) has to be </li></ul><ul><li>demonstrated with algorithms suitable for EF (LVL2). </li></ul><ul><li>Work is continuing on EF selections for B d,s - >  X  channels. </li></ul>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
    4. 4. 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 <ul><li>Event Filter Selection: </li></ul><ul><li>Tighter mass cut </li></ul><ul><li>Vertex fit cuts : </li></ul><ul><ul><li> 2 / N d.o.f. < 8, </li></ul></ul><ul><ul><li>L xy > 100  m, </li></ul></ul><ul><ul><li> xy < 5 </li></ul></ul><ul><li>Level-2 selection: </li></ul><ul><li>Tracks separated from trigger  by  R  > 0.2 </li></ul><ul><li>p T > 3.9 GeV </li></ul>o <ul><li>Two opposite sign tracks with: </li></ul><ul><li>p T + p T > 10 GeV </li></ul><ul><li> z 0 < 2 cm </li></ul><ul><li>4.3 < M(  ) < 6.3 GeV </li></ul>+ -  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
    5. 5. D s  Trigger o <ul><li>Level-2 Selection: </li></ul><ul><li>Tracks: p T > 1.4 GeV </li></ul><ul><li> R  > 0.2 w.r.t. trigger  </li></ul><ul><li>EF Event Selection: </li></ul><ul><li>Tracks: p T > 1.5 GeV </li></ul><ul><li>Mass cuts : </li></ul><ul><li>M(KK) - M(  ) < 14 MeV </li></ul><ul><li>M(KK  ) - M(D s ) < 56 MeV </li></ul><ul><li> vertex fit cuts: </li></ul><ul><li> 2 prob. >0.5%, L xy > 200  m </li></ul><ul><li>D s vertex fit : </li></ul><ul><li> 2 prob. >0.5%, L xy > 200  m </li></ul><ul><li>Two opp. sign tracks satisfying: </li></ul><ul><li>M(KK) - M(  ) < 17 MeV (~3  trigger ) </li></ul><ul><li>Third track with: </li></ul><ul><li>M(KK  ) - M(D s ) < 74 MeV (~3  trigger ) </li></ul>New selection cuts by Innsbruck <ul><li>Level-2 Efficiencies for </li></ul><ul><li>B s D s (  (KK))  events with pile-up </li></ul><ul><li>(L = 10 33 cm -2 s -1 ): </li></ul><ul><li>58% : Signal events with </li></ul><ul><li>p T (  ,  and K) > 1.5 GeV </li></ul><ul><li>63% : Signal events selected offline </li></ul><ul><li>3% : Background B  X </li></ul><ul><li>events </li></ul><ul><li>Level-2 Trigger rate ~150 Hz </li></ul><ul><li>for 5 kHz  6 </li></ul><ul><li>EF selection reduces rate to </li></ul><ul><ul><li>21 Hz 4  offline mass cuts </li></ul></ul><ul><ul><li>17 Hz 3.5  offline mass cuts </li></ul></ul><ul><ul><li>13 Hz 3  offline mass cuts </li></ul></ul><ul><ul><li>for 5 kHz  6 </li></ul></ul><ul><ul><li> offline (  ) = 3.4 MeV </li></ul></ul><ul><ul><li> offline ( D s ) = 14 MeV </li></ul></ul>
    6. 6. 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.
    7. 7. J/  e  e  Trigger <ul><li>Event Filter Selection: </li></ul><ul><li>Tighter mass cuts </li></ul><ul><li>Vertex fit cuts : </li></ul><ul><ul><li> 2 / N d.o.f. < 8, </li></ul></ul><ul><ul><li>L xy > 220  m, </li></ul></ul><ul><ul><li> xy < 40 </li></ul></ul><ul><li>Two opposite-sign e tracks with: </li></ul><ul><li>p T + p T > 4 GeV </li></ul><ul><li>|  | < 1.4, |  z 0 | < 2 cm </li></ul><ul><li>cos(  ee ) > 0.2 </li></ul><ul><li>2 < M(ee) < 3.5 GeV </li></ul>+ - <ul><li>Level-2 Selection: </li></ul><ul><li>Tracks: p T > 0.5 GeV </li></ul><ul><li>Identified as electrons by TRT </li></ul>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
    8. 8. 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 <ul><li>Study by Moscow of effect of raising </li></ul><ul><li>p T threshold for e in J/  (ee) trigger </li></ul><ul><li>Further rate reduction, with some loss of </li></ul><ul><li>physics, e.g. : </li></ul><ul><li>Raising p T cut from 0.5 GeV to 0.8 GeV </li></ul><ul><li>gives </li></ul><ul><ul><li>Rate reduced from 17 Hz to 8 Hz </li></ul></ul><ul><ul><li>4% efficiency loss for B d - > J/  (ee) K 0 </li></ul></ul>100 80 60 40 20 0 0.5 1.0 1.5 2.0 2.5 3.0
    9. 9. B-physics Trigger Rates - Example of tighter cuts muon p T >6 (ID+muon) EF 5 kHz <ul><li>Note: </li></ul><ul><li>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. </li></ul>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
    10. 10. 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
    11. 11. Future Work - Robustness <ul><li>Robustness Studies: </li></ul><ul><li>Extend LVL2 robustness studies to J/  channel including TRT </li></ul><ul><li>Compare robustness of TRT-guided c.f. pixel-guided reconstruction for J/  </li></ul><ul><li>Look at EF selection, expected to be more sensitive than LVL2 due to: </li></ul><ul><ul><li>vertex fit quality cuts </li></ul></ul><ul><ul><li>transverse decay length cuts </li></ul></ul><ul><ul><li>tighter mass cuts </li></ul></ul><ul><ul><li>. </li></ul></ul>Easter 2001 Moscow End 2001?? Who?? Easter 2001 Moscow
    12. 12. Future Work - LVL2 <ul><li>LVL2 Studies: </li></ul><ul><li>Repeat B-trigger measurements including muon simulation (previously used Kine). </li></ul><ul><li>Effect of New layouts: </li></ul><ul><ul><li>- evaluate effect of latest ID layout (Insertable pixel layout). </li></ul></ul><ul><li>LVL2 Algorithm Development : </li></ul><ul><li>Scan of pixels+SCT (more robust than pixel-scan) two techniques: </li></ul><ul><li>- based on pixel-scan : Genova </li></ul><ul><li>- based on hit filtering algorithm + kalman fitter : Nikos </li></ul><ul><li>Vertex reconstruction at LVL2 - Nikos? </li></ul><ul><li>Reproduce cTrig functionality in new framework </li></ul><ul><li>Add new functionality in new framework: </li></ul><ul><ul><li> and e reconstruction in ID RoI </li></ul></ul>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?
    13. 13. Future Work - EF Selection <ul><li>EF Selections : </li></ul><ul><li>Investigate EF selections for B - >  X channels </li></ul><ul><li>Check compatibility of cuts with offline selections, particularly background estimations, systematic bias etc. </li></ul><ul><li>Check effects of layout changes </li></ul><ul><li>Timing measurements for B-selections, development of algorithms suitable for EF (ID, Muon, Calorimeter reconstruction). </li></ul>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??
    14. 14. Datasets <ul><li>Datasets with ID ‘insertable’ layout, modular TRT, true solenoid B-field: </li></ul><ul><li>Single particle datasets for tests </li></ul><ul><li>Whole detector (incl. muons): </li></ul><ul><ul><li>Signal datasets : </li></ul></ul><ul><ul><ul><li> 6 + B  , </li></ul></ul></ul><ul><ul><ul><li> 6 + B D s  B D s a 1 , </li></ul></ul></ul><ul><ul><ul><li> 6 + B J/  (ee), </li></ul></ul></ul><ul><ul><ul><li>B J/  (  6,  ), </li></ul></ul></ul><ul><ul><ul><li>B  (X) </li></ul></ul></ul><ul><ul><li>Background : B  X </li></ul></ul><ul><ul><li>Datasets for studies with  and e in LVL2 RoI from ID: </li></ul></ul><ul><ul><ul><li> 6 + B J/  (e5e) </li></ul></ul></ul><ul><ul><ul><li>e5 + B J/  (  6,  ) </li></ul></ul></ul><ul><ul><ul><li>B J/  (  6,  ) </li></ul></ul></ul>Easter 2001? Autumn 2001?? End 2001??
    15. 15. 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.
    16. 16. Summary <ul><li>D s (  (KK)  ) trigger: tighter EF cuts studied => ~halving of rate. </li></ul><ul><li>Effect of raising muon p T thresholds studied, but signal efficiency falls rapidly </li></ul><ul><li>J/  (ee) trigger: raising e p T threshold studied, can ~halve rate for 4% signal loss. </li></ul><ul><li>Robustness studies: </li></ul><ul><ul><li>LVL2 Trigger robust w.r.t. SCT misalignment. </li></ul></ul><ul><ul><li>Pixel R  misalignment limit: 15  m (barrel). </li></ul></ul><ul><ul><li>Trigger robust w.r.t. SCT inefficiency. </li></ul></ul><ul><ul><li>Main concern is impact of dead pixels on pixel-scan efficiency, but a new more robust algorithm is being developed. </li></ul></ul><ul><ul><li>Studies will be extended to the J/y(ee) trigger and TRT </li></ul></ul><ul><ul><li>Studies will be extended to EF if someone can be found for this work. </li></ul></ul><ul><li>Algorithm development is continuing. Vertex finding at LVL2 will be investigated. </li></ul><ul><li>Studies started for EF selection for B  (X), initially at the particle level. </li></ul><ul><li>Future work will be focussed on: </li></ul><ul><ul><li>new data-sets with the whole detector and updated ID layout. </li></ul></ul><ul><ul><li>additional functionality in the new s/w framework leading to a simulation of the complete B-physics trigger menu ~end 2002. </li></ul></ul>

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