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Commissioning the LHCb calorimeters with cosmic rays

Commissioning the LHCb calorimeters with cosmic rays. Xavier Vilasis-Cardona On behalf of the LHCb calorimeter group. 1 st  international conference on Technology and Instrumentation in Particle Physics TIPP09-Tsukuba, Japan, March 2009. LHCb Calorimeters. RICH 1 & 2 PID: K vs. π.

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Commissioning the LHCb calorimeters with cosmic rays

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  1. Commissioning the LHCb calorimeters with cosmic rays Xavier Vilasis-Cardona On behalf of the LHCb calorimeter group 1st international conference onTechnology and Instrumentation in Particle Physics TIPP09-Tsukuba, Japan, March 2009 Xvc - TIPP09

  2. LHCb Calorimeters RICH 1 & 2 PID: K vs. π • Preshower (PS)/Scintillator Pad Detector (SPD) • Electromagnetic Calorimeter (ECAL) • Hadronic Calorimeter (HCAL) See Andreas Schopper Talk 10-250 mrad 10-300 mrad MAGNET Y~7m X~8.5m PS/SPD HCAL ECAL Muon Stations Calorimeters PID: e,, 0 VELO Vertexing Trackers TT+IT+OT Momentum resolution Z~2.7m Xvc - TIPP09

  3. Commissioning Tools • Noise measurements • Inject known patterns into system memories • LED system • ECAL, HCAL, PS, SPD • Cs source for HCAL • Time Alignement events -TAE events • Store trigger + previous and next Bunch Crossing ID (Clock cycle identifier - BXID) • Up to 15 samples • usually 5, • Prev2, Prev1, T0, Next1, Next2 • COSMIC RAYS • Injection Test Events Xvc - TIPP09

  4. Full System Test (May 2007) LED system Calibration Pulse ECAL Crate Storage Concrete WALL TFC DAQ ECS Control Room Xvc - TIPP09

  5. Cosmics at LHCb • Vertical flow in cavern: • 0.9 Hz/m2 (under HCAL), <E>=50 GeV. • PMT highvoltages set initiallytoobtainanuniformgainon PMT of 2·105 • Triggerstrategies • Firstcosmicsseen in December 2007 • Overall more than 3M cosmictriggers L0 Decision Unit ECAL AND OR HCAL 5-15 Hz SPD mult. Muon Xvc - TIPP09

  6. Example of Cosmic Event in the Calorimeter ECAL HCAL PS SPD Cosmic event in the 4 calorimeter detectors Xvc - TIPP09

  7. Another cosmic event HCAL HCAL ECAL PS ECAL SPD PS SPD Xvc - TIPP09

  8. Cosmic Ray crossing the SPD Xvc - TIPP09

  9. Cosmics use • Check channel map identification along the DAQ and trigger path. • Relative Time Alignment • Bunch Crossing ID (Clock cycle identifier) • Integration time • Track reconstruction in the Calorimeter • PreShower and SPD Efficiency • Provide Trigger for other subdetectors Xvc - TIPP09

  10. Correct channel mapping with comics Missing signal due to mapping error in software (may 2008) Corrected Xvc - TIPP09

  11. Trigger path validation with cosmics Wrong Trigger Cabling should deliver this Actually we had this Xvc - TIPP09

  12. Detector time alignement (muon vs calo) • Calo-triggered event Time slot Time slot • Muon-triggeredevent: Muon signal seen 2 clock cycles earlier Time slot Time slot 22/04/2008 Pascal Perret - LPC Clermont Xvc - TIPP09

  13. Time Alignment Strategy • Equalise an a-priori delay from theoretical values • Adjust BXID so that an event is mainly seen on Current • Adjust integration time t0 • Select the pair of BX with maximum signal • Prev1/Current vs. Current/Next1 • Compute the asymetry R δTsampling δTsampling δTsampling 25 ns t Prev1 T0 Next1 Xvc - TIPP09

  14. ECAL / HCAL time alignment Within each detector the RMS of R is coherent with time aligned cells within 3 ns HCAL ECAL Xvc - TIPP09

  15. PS time alignment • Integration time is the same for 1 PMT(64 channels) PS aligned within 4ns Outer Middle Inner Xvc - TIPP09

  16. SPD time alignment • SPD has binary output • Integration time is the same for groups of 64 channels • Asymetry is computed over the shape of the average ratio of detected particles Full SPD aligned within 5 ns Xvc - TIPP09

  17. Calorimeter Track Reconstruction • A tool has been developped to reconstruct tracks in the calorimeter • Determineazimuthal angle (φ) in HCAL & ECAL and combine them • Select eventswithχ²<15 • Selectedtracks are extrapolated for position & timing • PS/SPD • Othersubdetectors Xvc - TIPP09

  18. PS & SPD Efficiencies • PS • Efficiency 87 % • SPD efficiency as a function of threshold • Threshold at 9σ above noise: ~500k 94% • Threshold at 0.5 MIP : ~1M 82 % • Threshold at 1.5 MIP : ~500k 19.6% Xvc - TIPP09

  19. PS calibration with cosmics • FromCosmicsevents : • Each PS regioncalibrated – using the time model of signals Xvc - TIPP09

  20. Injection tests events Connectics problems SPD PS Flow  0.1-1 MIP/cm2 Pascal Perret - LPC Clermont 3/09/2008 • SPD multiplicity was used as trigger for LHC synchronization tests • 1 injection test shot  3 h Cosmics • Coherent with cosmics results Xvc - TIPP09

  21. Conclusions • Calorimeter system has provided cosmic triggers to the LHCb detector • Cosmics have allowed a first approximation to • Time alignment • Efficiency • This procedures will be repeated with the first data • And we are now of course Eagerly waiting for collisions ! Xvc - TIPP09

  22. Commissioning the LHCb calorimeters with cosmic rays Xavier Vilasis-Cardona On behalf of the LHCb calorimeter group 1st international conference onTechnology and Instrumentation in Particle Physics TIPP09-Tsukuba, Japan, March 2009 Xvc - TIPP09

  23. Backup Slides Xvc - TIPP09

  24. Photon – electron triggger path ECAL -> PS/SPD->TVB tested on cosmics Xvc - TIPP09

  25. Data Quality Survey • Check of connections with cosmics • With 900 events, if all cables were not plugged or if backplane connections were wrong, we would see (ie we checked that all cables are plugged at the correct place): 22/04/2008 Pascal Perret - LPC Clermont Xvc - TIPP09

  26. Time alignement PS/SPD & ECAL/HCAL # hits Prs #hits ECAL #hits SPD Bx #hits HCAL y y ECAL HCAL x Bx x # hits Prs #hits ECAL #hits SPD Bx #hits HCAL y y ECAL HCAL x Bx x Xvc - TIPP09

  27. HCAL & ECAL: Time Alignment Aout: 87k Event ECAL RMS(RMS R)=0.039 Improvement in the internal time alignment of the ECAL with the HV corrections HCAL Aout 29776 RMS(RMS R)=0.076 THCAL - TECAL Forward tracks – PP: Slope = 2.38 OffSet = -2.20 ns PP New Run 29 776 ΔL Pascal Perret - LPC Clermont 3/09/2008 Xvc - TIPP09

  28. Front End Electronics Xvc - TIPP09

  29. Calorimeter Trigger System Xvc - TIPP09

  30. LHCb DAQ System Xvc - TIPP09

  31. Cosmics in the calorimeter Xvc - TIPP09

  32. Cosmics at LHCb • Vertical flow in cavern: • 0.9 Hz/m2 (under HCAL), <E>=50 GeV. • Horizontal muons: • <E>=100 GeV • <30º; 0.0046 Hz/m2 (outer HCAL x 40 m2 = 0.18 Hz) • <11º; 0.0009 Hz/m2 (inner HCAL x 15 m2 = 0.013 Hz ) Xvc - TIPP09

  33. Time Alignment Strategy - SPD • SPD has binary output • Integration time is the same for groups of 64 channels • Asymetry has to be computed performing statistics over many events • Threshold value is capital • Too low : noise • Too high : no signal • Fixed at 9σ from the pedestal t0 (ns) t0 (ns) t0 (ns) 100 GeV PGun muons (SPD inner cell), 1k events, B off Threshold ~ 0.5 MIP Threshold ~ 0.25 MIP Xvc - TIPP09

  34. SPD threshold dependence • Using Cosmics sample study the efficiency as a function of threshold. • 9 sigma recipe: ~500k - 94% • 0.5 MIP recipe: ~1M - 82 % • 1.5 MIP recipe: ~500k -19.6% Correspondance of 9 sigma recipe to computed MIP • Correction needed for cosmics • Select cosmics in middle BX Xvc - TIPP09

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