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HERA-B

HERA-B. A. Zoccoli Università and INFN - Bologna. PRC open session 16 th May 2002. Outline. Status of the 2000 data analysis Detector and trigger: present status results of 2001 data analysis 2002/3 Physics program Summary. Trigger. Topic. Minimum bias no trigger.

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HERA-B

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  1. HERA-B A. Zoccoli Università and INFN - Bologna PRC open session 16th May 2002 A. Zoccoli - PRC open session 16-May-2002

  2. Outline • Status of the 2000 data analysis • Detector and trigger: • present status • results of 2001 data analysis • 2002/3 Physics program • Summary A. Zoccoli - PRC open session 16-May-2002

  3. Trigger Topic Minimum bias no trigger •  Ks0 & L production cross section. •  Inclusive particle productions. • L polarization  bb production cross section  Fraction of J/y from cc  Inclusive J/y xf & pt distributions  J/y production cross section Lepton pair: e+ e- ECAL pretrigm+m- Muon pretrig + SLT tracking Run 2000 Analysis Topics • Statistics • Minimum Bias: 2 million events(C, Al, Ti, W targets) • DiLepton trigger: 0.45 million eventsDI- 0.90 million eventsDI-e  IR ~ 5 MHz A. Zoccoli - PRC open session 16-May-2002

  4. K0 K0 0 0 0 Preliminary! Minimum Bias: V0 production V0 Cross section K0s & L mass distr. K0s & L nuclear dependence A. Zoccoli - PRC open session 16-May-2002

  5. Xf: Preliminary! pt : Dilepton trig. : Prompt J/ (Muon) Trigger tracks confirmed by reconstruction PID: likelihood from MUON detector and RICH A. Zoccoli - PRC open session 16-May-2002

  6. Preliminary! BR=0.340.020.02 Total number of J/ in the sample: nP= 5710380ST280SYS Dilepton trig. : Prompt J/ (Electron) Trigger tracks confirmed by reconstruction: Particle ID: E/P + bremsstrahlung A. Zoccoli - PRC open session 16-May-2002

  7.  C Ti ee Entries / 25 MeV/c2 C Ti All All M=M(J/)-M(J/) (GeV/c2) Fraction of J/y from cc cc J/y g Preliminary results: Rcc = 0.351  0.077  0.037 (Carbon) Rcc = 0.32  0.15  0.03 (Titanium) In agreement with previous p-N experiments. In 2002: - First measurement of cc suppression in nuclear matter. - Study of production ratios betweenJ/y , cc and Y‘. - Disentangle the 2 cc states (?) A. Zoccoli - PRC open session 16-May-2002

  8. b  J/ X  + - X b  J/ X  e+ e- X Look at the chain: via detached J/ vertices. upstream | downstream l+ J/ z l- B X IW The HERA-B (bb) Measurement Principle of the measurement: Normalizationon the inclusive prompt J/ cross section.  Systematic error minimization A. Zoccoli - PRC open session 16-May-2002

  9. Optimization procedure: Entries / 100 MeV/c2 + - invariant mass ( GeV/c2 ) The Muon Channel: b-cuts Cuts applied: z > 7.5z  Imp. Param. to wire Iw > 35 m  Imp. Param. to primary vtx Ip> 160 m Mass spectrum upstream and downstream: UNBINNED LIKELIHOOD FIT (due to low statistics): - Sig. shape from MC, - BKG shape from data. A. Zoccoli - PRC open session 16-May-2002

  10. Optimization procedure: Entries / 100 MeV/c2 e+e- invariant mass ( GeV/c2 ) The Electron Channel: b-cuts Cuts applied: z > 0.5cm e Imp. Param. wire Iw > 200 m, or Min. dist. @ ZW to any other track > 250 m UNBINNED LIKELIHOOD FIT (due to low statistics): - Sig. shape from MC, - BKG shape from data. Mass spectrum upstream and downstream: A. Zoccoli - PRC open session 16-May-2002

  11. E789: 5.7 1.5 1.3 nb/nucl. nb/nucl. E771: TOT(bb) = nb/nucleon (bb) Determination QCD calculations and experimental results: Simultaneous fit to e+e- & +- (in acceptance): Extrapolation to the Hera-B acceptance: A. Zoccoli - PRC open session 16-May-2002

  12. Summary of 2000 analysis • The analyses on Dilepton and Minimum Bias data taken during the 2000 run are well advanced. • Understanding of the detector, of the efficiencies, of the performances, etc. • Preparation of the analysis codes in view of the 2002/3 run.  Papersonbb cross section (almost final), production of J/y from cc , V0 production cross section and J/y decayspectra are in preparation. A. Zoccoli - PRC open session 16-May-2002

  13. 2002/3 Detector Configuration Thinner beam pipe: 500m  300m No magnet tracker!Motivation to reduce material: - Improve calorimeter performance. e.g. 1.5x better resolution on (c - J/) mass difference - Influence on tracking shown to be small at 5 - 10 MHz interaction rate. - (being kept in a safe place in case of possible future use) A. Zoccoli - PRC open session 16-May-2002

  14. Ecal noise situation Itr in 2002 Otr in 2002 Effect of Dead HV groups Repair, geometrical efficiency: New improved grounding scheme on all chambers: Noise reduction ADC pedestals in the new ECAL run configuration: Old • reduction of pick-up • lower fluctuation of raw data 2000 Run 100 Old Threshold ADC counts New Width of Raw Data [ADC] 90 December 2001 ~ 3% of dead channels vs ~15% in 2000. Stations • Higher efficiency expected To be measured in the near future Before magnet After magnet • Better performances in PId To be measuerd in the near future ADC counts Status of detector components • The HERA-B detector was operational in 2000 run. • Many improvements during the shutdown.  Partially checked in the short run end of 2001. A. Zoccoli - PRC open session 16-May-2002

  15. Status of First Level Trigger The First Level trigger was not fully commissioned in 2000. Low efficiency due to both trigger and detector performances. Main activities: • Optical Links: despite large effort, will remain the most critical HW item • Flt Algorithm fully optimized. • Processor logic fully verified (vector test). • Detector mapping ready, verification in progress • Online software improved system • New RICH multiplicity veto systemavailable Waiting for data to check the performance ! A. Zoccoli - PRC open session 16-May-2002

  16. 2000 K0 2001 0 December 2001 data Minimum Bias (int. Trig.):~500k events only ~10 hours RUN ! Charged tracks Checks on reconstruction and alignment, comparison with 2000 data: Inclusive distributions K0s & L mass distr. KS width already smaller than in 2000! A. Zoccoli - PRC open session 16-May-2002

  17. Inner Middle Outer December 2001 data - II Neutrals Checks on reconstruction and calibration: • 0 seen in the Outer. After one calibration iteration (out of three). Width very close to that of 2000. More data welcome ! A. Zoccoli - PRC open session 16-May-2002

  18. 2002/3 Physics Program Base line physics program for next run: A) Detailed measurement of atomic number dependence of charmonium production - Extend existing measurements of J/ and ’ to negative xF. - First measurement of atomic number dependence of c. B) Improved bb cross section measurement -Systematics limit at  15% (normalization).- Cross section from full reconstructed B mesons A. Zoccoli - PRC open session 16-May-2002

  19. 2002/3 Physics Program – II Additional topics: - Charmonium spectroscopy – Drell-Yan - Measurement of  production - Open charm production - Strangeness production in nuclear matter -  polarization Expected event yields: 2002/3 2000 J/y ( m & e )~4 106 ~1 104c J/y g~3 105 ~1 102 Y´ ~1 105 ~4 101 Targets: primarily C, W (but also installedTi, Al & Pd) Acceptancein the range -0.4 < xf < 0.3 A. Zoccoli - PRC open session 16-May-2002

  20. Summary • The analysis of 2000 data is approaching completion. • Improved performance of the HERA-B spectrometer and understanding of the trigger.  first data look promising  trigger ready to be tested • Physics program:very large statistics of charmonium states expected in the next run. A. Zoccoli - PRC open session 16-May-2002

  21. Summary HERA-B is anxiously waiting for new data to come. A. Zoccoli - PRC open session 16-May-2002

  22. A. Zoccoli - PRC open session 16-May-2002

  23. Bkg Downstream Bkg Bkg Dz (cm) Upstream Mass (ee) (GeV/c2) MC =0.810.03 cm RD =1.000.30 cm BKG=0.360.13 cm Systematic checks (e-channel) DECAY LENGTH LIKELIHOOD FIT: Different background optimisation: A. Zoccoli - PRC open session 16-May-2002

  24. Status of detector components • The HERA-B detector was operational in 2000 run. • Many improvements during the shutdown.  Partially checked in the short run end of 2001. A. Zoccoli - PRC open session 16-May-2002

  25. Itr in 2002 New improved grounding scheme on all chambers: Old • reduction of pick-up • lower fluctuation of raw data ADC counts New Width of Raw Data [ADC] Stations Before magnet After magnet ADC counts A. Zoccoli - PRC open session 16-May-2002

  26. Otr in 2002 Effect of Dead HV groups Repair, geometrical efficiency: Noise reduction 100 Old Threshold 90 ~ 3% of dead channels vs ~15% in 2000. • Higher efficiency expected To be measured in the near future A. Zoccoli - PRC open session 16-May-2002

  27. Ecal noise situation ADC pedestals in the new ECAL run configuration: 2000 Run December 2001 • Better performances in PId To be measuerd in the near future A. Zoccoli - PRC open session 16-May-2002

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