Download
operation experience n.
Skip this Video
Loading SlideShow in 5 Seconds..
Operation Experience PowerPoint Presentation
Download Presentation
Operation Experience

Operation Experience

125 Vues Download Presentation
Télécharger la présentation

Operation Experience

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. LHCbVErtexLOcator Operation Experience KazuAkiba On behalf of the Velo Group

  2. beauty at the LHC K+ • LHCbb production at low angle and in the same direction. • A B experiment at the LHC needs forward acceptance! • High b production cross section @ TeV energies • Even Higher background rates • LHCb’s scientific mission statement: • To precisely measure CP-violation in the B-system • To find Rare B Decays • To seek out New Physics • Key points: • Vertexing • Particle identification. • Trigger B0 PV Beam 1 K- π+ Beam 2 IP B0 D- LHCb σ(pp → Hb X) = ( 75 ± 5 ± 13 ) µb Phys. Lett. B 694, 209-216 (2010) Kazu Akiba

  3. The LHCb Experiment RICH2 TT Si Outer Tracker straw Tubes ECAL HCAL Magnet Zoom in the interaction region VELO&PU Si Closed For physics Muon MWPCGEM Inner Tracker Si Open during injection RICH1 Large HadronColliderbeauty Experiment for CP violation and Rare B Decays.

  4. VELO • 2 Retractable halves • 21 Modules /half • 1R & 1φ sensors/module • 2048 strips/sensor  172k channels • 300 µm n-on-n sensors! • 1 n-on-p • Active @ 8 mm. • Operated in a secondary vacuum,sensors and front-end Vacuum ! • Designed for: • Minimal material budget. • Excellent primary and secondary vertexing… and tracking. • Outstanding impact parameter resolution. Contains 1 Velo half Rf Foil 300 mm Kazu Akiba

  5. VELO • 2 Retractable halves • 21 Modules /half • 1R & 1φ sensors/module • 2048 strips/sensor  172k channels • 300 µm n-on-n sensors! • 1 n-on-p • Active @ 8 mm. • Operated in a secondary vacuum,sensors and front-end Vacuum ! • Designed for: • Minimal material budget. • Excellent primary and secondary vertexing… and tracking. • Outstanding impact parameter resolution. Contains 1 Velo half Rf Foil 300 mm Kazu Akiba

  6. VELO • 2 Retractable halves • 21 Modules /half • 1R & 1φ sensors/module • 2048 strips/sensor  172k channels • 300 µm n-on-n sensors! • 1 n-on-p • Active @ 8 mm. • Operated in a secondary vacuum,sensors and front-end Vacuum ! • Designed for: • Minimal material budget. • Excellent primary and secondary vertexing… and tracking. • Outstanding impact parameter resolution. Contains 1 Velo half Rf Foil 300 mm Kazu Akiba

  7. VELO • 2 Retractable halves • 21 Modules /half • 1R & 1φ sensors/module • 2048 strips/sensor  172k channels • 300 µm n-on-n sensors! • 1 n-on-p • Active @ 8 mm. • Operated in a secondary vacuum,sensors and front-end mbar Beam vacuum Velo mbar Vacuum ! • Designed for: • Minimal material budget. • Excelent Primary and Secondary Vertexing… and tracking. • Outstanding Impact Parameter resolution. • Designed for: • Minimal material budget. • Excellent primary and secondary vertexing… and tracking. • Outstanding impact parameter resolution. Contains 1 Velo half Rf Foil Kazu Akiba

  8. Sensors/Modules Sensor • Analogue readout from ASICS (Beetle) • on hybrids • Repeater cards outside tank – inaccessible when LHC is ON • Digitization 60m away – safe zone • FPGA processing • 106 parameters • Integer pedestals and CM subtractions • Clustering + Zero suppression Front-end: 40 MHz clock, 1 MHz readout Hybrid Active Cooling Biphase CO2 Carbon fibre support Kapton cables R-side circuit R-sensor Carbonfibre -sidecircuit x42 Data Config -sensor Kazu Akiba

  9. Sensors Modules silicon [oC] Sensor • Analogue from ASICS on hybrids • Repeater cards outside tank – inaccessible when LHC is ON • Digitization 60m away – safe zone • FPGA processing • 106 parameters • Integer pedestals and CM subtractions • Clustering + Zero suppression -5oC Front-end: 40 MHz clock, 1 MHz readout Silicon temperature as function of cooling setpoint 10 Hybrid VELO fully powered -15oC Active Cooling Biphase CO2 5 0 Carbon fibre support -25oC Kapton cables -5 -30oC R-side circuit R-sensor -30oC Carbonfibre -10 Cooling performance very stable so far -sidecircuit -35oC x42 Data Stable behaviour. Work point: -30 oC nice low silicon work temperature of -10oC Config -sensor Kazu Akiba

  10. Time Alignment • Fine tune timing is an automated procedure • Overall precision of ± 1 ns • Aim for • Maximum signal/noise • Minimal neighbouring bunch cross talk. • Sensors individually tuned to account for differences in • Time of flight • Cable length

  11. Running 2010-11 • Higher Occupancy, collisions/crossing, then designed for. • Nominal Instantaneous luminosity achieved in May/2011! Kazu Akiba

  12. Running 2010-11 • Higher Occupancy, collisions/crossing, then designed for. • Nominal Instantaneous luminosity achieved in May/2011! Vis Collision Pile-UP ATLAS/CMS Upgrade LumiLeveling Displacing the beams LHCb Now Nominal KazuAkiba

  13. Running 2010-11 • Higher Occupancy, collisions/crossing, then designed for. • Nominal Instantaneous luminosity achieved in May/2011! • Running with 24/7 shifters in 2010. • Safety of the detector ensured. • Careful HV ramping and moving the detector upon stable beams • Front-end configured at all times except “MD” • Data quality constantly checked. • Stability in 2010 pushed toward no VELO shifter operations in 2011: • 2 people on call 24/7: data quality + hardware experts. • Powering and moving are now automated, but human confirmed. • Interfill time is used for standard checks. • IV curves and calibration runs constantly taken • Checks for any increase of noisy/dead strips. • DAQ parameters determination and uploading streamlined • Problems found with pedestal drifting • Complete retuning of the system can be done within a day. • NZS data taken all the time: all detectors together in separate stream => CM studies to be performed. HV and LV stable through 2010-11 KazuAkiba

  14. Running 2010-11 • Higher Occupancy, collisions/crossing, then designed for. • Nominal Instantaneous luminosity achieved in May/2011! • Running with 24/7 shifters in 2010. • Safety of the detector ensured. • Careful HV ramping and moving the detector upon stable beams • Front-end configured at all times except “MD” • Data quality constantly checked. • Stability in 2010 pushed toward no VELO shifter operations in 2011: • 2 people on call 24/7: data quality + hardware experts. • Powering and moving are now automated, but human confirmed. • Interfill time is used for standard checks. • IV curves and calibration runs constantly taken • Checks for any increase of noisy/dead strips. • DAQ parameters determination and uploading streamlined • Problems found with pedestal drifting • Complete retuning of the system can be done within a day. • NZS data taken all the time: all detectors together in separate stream => CM studies to be performed. HV and LV stable through 2010-11 Problem showed to be highly correlated to the trigger rate… Kazu Akiba

  15. Operational Issue: Closing • The flags “stable beams” and “movable devices allowed in” set to TRUE by the LHC. • HV is ramped up. Temperatures, bias currents, occupancies are checked. • Closing manager “asks” to close the VELO • Calculation of the beam position relative to each half and global. • Four steps in x: • 29 mm - 14 mm - 5 mm - 1 mm – closed • Constant check of the safety list • Calculation of the next position • Human re-confirmation at 1 mm. • movement in y if request > 50 mm Kazu Akiba

  16. Operational Issue: Closing • The flags “stable beams” and “movable devices allowed in” set to TRUE by the LHC. • HV is ramped up. Temperatures, bias currents, occupancies are checked. • Closing manager “asks” to close the VELO • Calculation of the beam position relative to each half and global. • Four steps in x: • 29 mm - 14 mm - 5 mm - 1 mm – closed • Constant check of the safety list • Calculation of the next position • Human re-confirmation at 1 mm. • movement in y if request > 50 mm Done about 100 times this year! Kazu Akiba

  17. Operational Issue: Closing • The flags “stable beams” and “movable devices allowed in” set to TRUE by the LHC. • HV is ramped up. Temperatures, bias currents, occupancies are checked. • Closing manager “asks” to close the VELO • Calculation of the beam position relative to each half and global. • Four steps in x: • 29 mm - 14 mm - 5 mm - 1 mm – closed • Constant check of the safety list • Calculation of the next position • Human re-confirmation at 1 mm. • movement in y if request > 50 mm Fraction of the inefficiency due to the Velo closing procedure Kazu Akiba

  18. Operational Issue: Closing • The flags “stable beams” and “movable devices allowed in” set to TRUE by the LHC. • HV is ramped up. Temperatures, bias currents, occupancies are checked. • Closing manager “asks” to close the VELO • Calculation of the beam position relative to each half and global. • Four steps in x: • 29 mm - 14 mm - 5 mm - 1 mm – closed • Constant check of the safety list • Calculation of the next position • Human re-confirmation at 1 mm. • movement in y if request > 50 mm Partly due to a bug in the derandomizer of Beetle ASIC Which increases with the rate. Kazu Akiba

  19. Once closed, then Monitor • Beam Condition Monitor (BCM), Beam Position Monitor (BPM)constantly checked. • DAQ system must “be working”. • Vertex Position is monitored online at all times. • HV currents are checked for “abnormal correlated fluctuations” • If one condition is not satisfied  “Grace Period” Move out to 14 mm . • 32 Conditions based on 32 parameters. Kazu Akiba

  20. Once closed, then Monitor • Beam Condition Monitor (BCM), Beam Position Monitor (BPM)constantly checked. • DAQ system must “be working”. • Vertex Position is monitored online at all times. • HV currents are checked for “abnormal correlated fluctuations” • If one condition is not satisfied  “Grace Period” Move out to 14 mm . 32 Conditions based on 32 parameters. Kazu Akiba

  21. Operational Issue: Performance • R -sensors: • Noise increases with strip length (radius). • 4 sectors of 512 strips cross talk from Beetle header • All S/N > 17... Still. • But 1/pb per hour... 3 types of strips in f sensors • outer – WITHOUT • overlaid routing lines • inner – routed over • outer strips • outer – WITH • overlaid routing lines KazuAkiba

  22. Operational Hazards: Radiation Damage Disclaimer: Depletion voltage around 40-80V initially. Depletion voltage decreases with fluence till type inversion (n-on-n) • Current vs Voltage (IV) • Taken weekly • Current increases with bulk damage, linearly related to fluence • Does not study depletion voltage • Noise vs applied bias Voltage • Taken monthly • Sensors decrease capacitance and hence noise when depleted, so sensitive to depletion voltage at least during early running • Charge Collection Efficiency vs applied bias voltage • Direct measure of physics relevant parameter • Can study radiation damage as function of position • Requires beam data so only taken a few times per year • April 2010 (~none), April 2011 (40/pb) Kazu Akiba

  23. Radiation Damage: IV curves n-on-n sensor n-on-p sensor (similar z position) Annealed at 20 o.C over shutdown As well. Kazu Akiba

  24. Radiation Damage: Noise Vs Voltage Measure the change in the Effective Minimal Noise Voltage EMNV, when 1/noise passes 80% of final noise . Innermost strips on R sensor most irradiation Ratio < 1, i.e. , smaller EMNV Outermost strips on R sensor less irradiation Ratio ~ 1, i.e. no change in EMNV Kazu Akiba

  25. Observed “Fluences” LHCbVelo Preliminary Minimum bias data LHCbVelo Preliminary LHCbVelo Preliminary LHCbVelo Preliminary VELO TDR KazuAkiba

  26. Observed “Fluences” LHCbVelo Preliminary Minimum bias data LHCbVelo Preliminary LHCbVelo Preliminary LHCbVelo Preliminary VELO TDR KazuAkiba

  27. Summary • Smooth Operations of the VELO over the past ~350/pb (~400/pb delivered counting 2010 too ) • Troublesome at times but working fine • Tracking and alignment performance reported by S.Borghi. • Hope to have much more Radiation Damage till the end of 2011 (and 1/fb)! Kazu Akiba

  28. Kazu Akiba

  29. BACK UP Kazu Akiba

  30. Common Mode Kazu Akiba

  31. Radiation Damage: CCE Charge Collection Efficiency – The Method: • Blue – tracking sensors at full bias voltage • Red – test sensors bias voltage scanned • 10V steps, 0V-150V • Rotate through patterns, fully automatic scan procedure • Tracks fitted through tracking sensors • Charge collected at intercept point on test sensors measured as function of voltage • Non-zero suppressed data taken  full charge recorded • Can study regions of sensor Kazu Akiba

  32. Radiation Damage: CCE Measure CCE(V)  Estimate the Effective Depletion Voltage: EDV = V(CCE = 80%) Similar Zones as previously Kazu Akiba

  33. Radiation Damage: IV curves n-on-n sensor Annealed at 20 o.C over shutdown As well. Note the different scales KazuAkiba