1. Andreas Schopper Overview of the LHCb Calorimeter System TIPP09 Tsukuba, Japan 12-17 March 2009 Tsukuba, March 2009TIPP091 presented by Andreas Schopper (CERN) on behalf of the Collaboration Outline:  Overview of LHCb & requirements to the calorimeter system  Design, construction & performance of the sub-systems  Conclusion

2. Andreas Schopper LHCb Detector Overview Interaction Point HCAL ECAL PS/SPD Tsukuba, March 20092TIPP09

3. Andreas Schopper Purpose of the LHCb Calorimeter System Preshower (PS) and Scintillator Pad Detector (SPD): PID for L0 electron and photon trigger electron, photon/pion separation by PS photon/MIP separation by SPD charged multiplicity veto by SPD Electromagnetic Calorimeter (ECAL): E t of electrons, photons and π 0 for L0 trigger (e.g. B → J/Ψ Ks, B → K*γ) reconstruction of π 0 and prompt γ offline particle ID Hadron Calorimeter (HCAL): E t of hadrons for L0 trigger (e.g. B → π π, B → D s K) particle ID L0 trigger => Calorimeters readout every 25ns Y~7m X~8.5m Z~2.7m HCAL ECAL PS/SPD Tsukuba, March 20093TIPP09 Detector requirements

4. Andreas Schopper  Measure energy and identify γ/e/h using SPD/PS/ECAL/HCAL in coincidence  Used at the fast Level-0 trigger 40 MHz hardware trigger. identify high P t particles that could sign a B decay use Calorimeter and Muon sub-systems 10 MHz visible interactions → 1 MHz  SPD & PS validate the charged and EM nature of incoming particle, respectively 1 1 0 0 1 Level-0 calorimeter trigger Tsukuba, March 20094TIPP09

5. Andreas Schopper ECAL & HCAL choice of technology ECAL design requirements:  energy resolution ~ 10%/√E  1%  fast response time compatible with LHC bunch spacing of 25 ns  radiation hard up to ~250 krad/year  small transverse segmentation to separate two showers from πº decays and to minimize pile-up  lateral size of active area 7.8m x 6.3m  cost effective  “shashlik” module Tsukuba, March 20095TIPP09 HCAL design requirements:  fast (25 ns cycle)  moderate resolution is sufficient ~ 80%/√E  10%  radiation tolerance up to ~50 krad/year in the inner zone  transverse segmentation to minimize pile-up  longitudinal depth limitations  lateral size 8.4m x 6.8m  cost effective  “tile-cal” module  common readout electronics  sampling technology using scintillators & fibres with readout by common photomultiplier & FE electronics

6. Andreas Schopper ECAL Shashlik modules Fibres with loopsScintillators, lead-plates, covers End- cover Lead plate Scintillator TYVEK Front- cover PMT and CW base CW base PMT 3312 shashlik modules with 25 X0 Pb Inner Module 9 cells: 4x4 mm 2 Middle Module 4 cells: 6x6 mm 2 Outer Module 1 cell: 12x12 mm 2 Tsukuba, March 20096TIPP09 Sc:Pb = 4:2 mm 25 X0 Hamamatsu R7899-20 12x12 mm 2 Kuraray Y-11(250) MSJ

7. Andreas Schopper ECAL module performance Tsukuba, March 20097TIPP09 PM anode current pulsePulse after clipping chain ‘dead time’-less shaping & integration of PM signal at 40 MHz E [GeV] EE  (0.83  0.02)%  ((145  13) MeV)/E (9.4  0.2) %  E E Energy resolution with electrons (outer type module) InnerMiddleOuter per cell, Nph.e./GeV 310035002600 MIP response, cell-to-cell variation, % 8%5.3%6.7%

8. Andreas Schopper ECAL uniformity of light response Tsukuba, March 2009TIPP098 RD 36 ~7% Uniformity parameters  A global = ( 0.46  0.03 )%  A local = ( 0.39  0.01 )% X [mm] ADC channels Transverse scan with 50 GeV electronsTransverse scan with 80 GeV electrons

9. Andreas Schopper Simulation of response uniformity Tsukuba, March 2009TIPP099 Compensate dead material of 0.2 mm thick steel tape between modules with diffractive white edge MC modeling: light collection efficiency  ray tracer program (refraction, reflection, attenuation...) Scintillator thickness  measured Convolution with particle energy deposition  GEANT Scan with muons between fibres tiles thickness variation diffractive white edge Scan with muons near fibres fibres position Scan with muons near fibres fibres position Data (points) vs simulation (grey area)

10. Andreas SchopperTIPP09 ECAL structure & integration  Large Shashlik array ~50 m 2 with 3312 modules and 6016 channels  Modular wall-like structure of 7.8 m x 6.3 m  Total weight of 80 tons  Three sections (Inner, Middle and Outer) of 4x4, 6x6, 12x12 mm 2  Two independently retractable halves to ease maintenance  Front-End electronics hosted on top of detector  ECAL dynamic range: follows ‘transverse energy’ rule: E(max)=7 + 10 /sin(θ)  LED based Monitoring System Chariot Electronic platform modules Beam plug Tsukuba, March 200910

11. Andreas Schopper LED monitoring system of ECAL Tsukuba, March 2009TIPP0911 LED LED Driver Splitter PIN diode ADC LED PMT … Basic requirements  Control of time and temperature stability  Small pulse duration and dispersion of amplitude  Adjustable pulse rate and amount of light  Emulate e/m particles in full “physics” region  Gain control to better than 1% accuracy  Control only electronics chain  supply LED light directly to the PMT  Use empty bunches for running monitoring system In total  512 LED drivers & LEDs & splitters & fiber-bundles  64 PIN-diodes LED pulse 50 GeV e -

12. Andreas Schopper Calibration strategy of ECAL Method level of accuracy periodicity 1.Cosmics test ~10%done before installation of ECAL 2.Energy flow ~5 %every 6 months/after shutdowns 3.pi0 & e reconstruction ~1%every few days/weeks 4.Monitoring with LED stabilityevery few minutes to follow relative gain variation Tsukuba, March 200912TIPP09 Absolute calibration with resolved πº Absolute calibration with electrons MC

13. Andreas Schopper particles PMT scintillators WLS fibers light- guide Internal cabling CW base PMT housing Module with optics assembled 52 modules with longitudinal tiles Tsukuba, March 200913TIPP09 HCAL tile-cal modules

14. Andreas Schopper 14 HCAL module performance Pulse shapes from each tile row measured by scanning the HCAL module transversely with an e - beam (  pulse shape as function of depth) 25 ns Row 1 Row 2 Row 3 ▲ Row 4 Row 5 ♦ Row 6 PM gains: 20k … 350k PM transit time (~1/√HV) +time of flight vary by ~5 ns Signal cable delay spread: ~2 ns Signal variations due to detector depth and mirrors at fiber ends HV settings for physics: correspond to E max =15 GeV/sin(Θ) (trigger on E T ) Tsukuba, March 2009TIPP09

15. Andreas Schopper HCAL module performance Tsukuba, March 2009TIPP0915 ~3% angular dependence at higher energies: shower not fully contained in 5.6 λ I Average light yield: 105 ph.el./GeV Energy resolution Angular dependenceLight yield

16. Andreas Schopper HCAL structure & integration Tsukuba, March 2009TIPP0916 Electronics platform Chariot modules Beam plug  Two independently retractable halves each consisting of 26 modules stacked on a movable platform  size of active area: 8.4 x 6.8 m 2  instrumented depth: 120 cm  cell size: outer zone 262 x 262 mm 2 inner zone 131 x 131 mm 2  1488 cells (608 outer + 880 inner)  LED based Monitoring System  built-in 137 Cs calibration system for in situ calibration Weight : ~9.5 ton

17. Andreas Schopper LED monitoring system of HCAL Tsukuba, March 2009TIPP0917  blue LEDs (WU-14-750BC)  two independent LEDs per module  adjustable LED pulse amplitude  monitoring PIN photodiode at each LED in order to account for LED instability  light distribution with clear fibers of same length  timing of the LED flashing pulse adjustable with 1 ns step 0.2% Monitoring of LED with PIN diode

18. Andreas Schopper Calibration system of HCAL Tsukuba, March 2009TIPP0918 ±20% Distribution of RMS (%) of the light yield of tiles belonging to the same PMT  Average: 4.7% Testbeam measurements show that independent calibrations with Cs source and 50 GeV π ― coincide within 2-3% All HCAL modules have undergone Cs test during production with requirement that tile response has to be within ±20% of average

19. Andreas SchopperTsukuba, March 2009TIPP0919 Signal processing  Shaper integrator + 12-bit (80 pC) 40 MHz two-stage bipolar flash ADC + delay chip to compensate for different arrival times of PM signals  pedestal subtraction (suppression of low-frequency noise)  conversion to 8-bit E t calibrated signal Selection of cluster candidate with highest E t for L0 Formatting of data block and dispatch it to the DAQ (upon request) ECAL & HCAL readout electronics

20. Andreas Schopper SPD & PS choice of technology Tsukuba, March 2009TIPP0920 SPD & PS design requirements:  fast response time compatible with LHC bunch spacing of 25 ns  match transverse segmentation of ECAL  full projectivity and minimal distance between SPD and PS for efficient trigger  lateral size of active area 7.8m x 6.3m  radiation hard up to ~150 krad/year  cost effective  space constraint of 18 cm in depth (along beam pipe)!  Two layers of scintillator interspaced by 2.5 X0 lead with a total of 12’032 channels  Light transported via clear fibers to detector periphery, where PMTs are located Purpose of SPD & PS:  PS : electron/pion separation  SPD : photon/mip separation  part of very first trigger level at 40 MHz e-e-  SPD Pb PS ECAL

21. Andreas Schopper Multi Anode PMT VFE card MAPMT SPD VFE + ECAL PS particles Clear fibers Tsukuba, March 200921TIPP09 Scintillator + coiled fiber Side view of upper part Inner + Middle + Outer Modules SPD & PS modules e-e-  SPD Pb PS ECAL Super module with 2 x 13 modules Super module frame 16 super modules for PS & SPD thickness 15mm

22. Andreas Schopper SPD & PS module performance Tsukuba, March 2009TIPP0922 # cells Nphe/MIP PS:  Readout by 10 bit ADC  Noise below 1.2 ADC counts with ~10 ADC-counts/MIP SPD:  Digital readout (1 bit)  Noise below 3 mV with 100mV/MIP All super-modules tested with cosmics in horizontal position  ~25±15 photo-electrons per MIP Optimize light yield from  15 mm thick tile with coiled WLS fiber + ~3m long clear fibers and interconnects

23. Andreas Schopper Calibration of SPD & PS Tsukuba, March 2009TIPP0923 Electron Photon Energy deposit in SPD 23 MIP E (MeV) Events SPD threshold scan SPD threshold scan with MIPs E (GeV) MIP Single pions energy deposition in PS PS ADC spectrum Events Optimal position of threshold: ~0.7 MIP e-e-  SPD Pb PS ECAL

24. Andreas Schopper SPD & PS structure & integration Tsukuba, March 2009TIPP0924 4 super modules per half detector MAPMT + VFE R/O cables Moving cable trays VFE electronic boxes OUTER (cell 12x12cm 2 ) MIDDLE (cell 6x6cm 2 ) INNER (cell 4x4cm 2 ) SPD PS Lead  PS+SPD built from a total of 16 super modules  segmentation matches (projective) ECAL cell size  total of 12’032 channels

25. Andreas Schopper Monitoring of SPD & PS with LED and particles Tsukuba, March 2009TIPP0925 Each of the 12’032 cells is equipped with a LED LED signals used:  to detect dead channels  to check the detector stability  for coarse time alignment 2D display during commissioning of PS showing peak ADC value of LED flash with subtracted pedestal Normalize to neighboring cells 5 Hz online event reconstruction to monitor with particles

26. Andreas SchopperTsukuba, March 2009TIPP0926 Light transporter by clear fibers to 64 anode PMT  very front-end away from beam : no radiation problem Dynamic range : 0 – 100 MIPs and accuracy required ~ 10%  PS : electron/pion separation  10 bits  SPD : photon/mip separation  1 bit 25±15 photo-electrons per MIP  large fluctuations 25 ns integrator mounted on the PMT – Reset with switches  Cheap and maximum use of the photo-electrons  Potentially more sensitive to noise, drift of pedestal and switch time versus beam crossing PS & SPD readout electronics digital 20-30m analog 27m

27. Andreas Schopper M(Kπ γ) (GeV/c²) σ(M B )~ 65 MeV/c² e.g. radiative B decays B d → K * γ B s → φ γ (Br = 2.9 x10 -5 ) (Br = 4.3 x10 -5 ) 35 x10 3 selected evts/year - B/S < 0.7 9 x10 3 selected evts/year - B/S < 2.4 Illustration : physics with prompt photons Tsukuba, March 200927TIPP09

28. Andreas Schopper Most of the inefficiency due to photon conversion before magnet Efficiency to reconstruct π o in B d → π + π - π 0 events MergedResolved Transverse momentum (GeV/c) B d → π + π - π 0 events ε = 53% (33% from resolved + 20% from merged) B d → π + π - π 0 (Br = 2.0 10 -5 ) 12. 10 3 selected evts/year - B/S < 1 ~ 60% with merged π 0 → γγ B u → ρ + ρ 0 (Br = 2.0 10 -5 ) 19. 10 3 selected evts/year - B/S < 1 ~ 30% with merged π 0 →γγ Illustration : physics with neutral pions Tsukuba, March 200928TIPP09

29. Andreas Schopper Commissioning with Cosmics LHCb geometry NOT well suited for cosmics… A challenge! Calorimeters used to trigger on useful ‘horizontal’ cosmics  Rate of ‘horizontal’ cosmics below 1 Hz, still very useful Collected a total of ~ 1.1Million triggers OT Calo Muon Tsukuba, March 2009TIPP0929

30. Andreas Schopper Readout of consecutive 25ns crossings for a single trigger Commissioning with Cosmics Tsukuba, March 200930TIPP09

31. Andreas Schopper Conculsions  The LHCb calorimeter system has been optimally designed to meet the trigger and physics requirements of LHCb  The 4 sub-detectors are using a common technology of scintillators & fibers readout by PMTs and common FE electronics  The system has been extensively used in the commisioning of LHCb and is fully ready for triggering and data taking Tsukuba, March 200931TIPP09

32. Andreas Schopper Spare slides Tsukuba, March 2009TIPP0932

33. Andreas Schopper 33 Hardware level (L0)  Search for high-p T , e, , hadron candidates Software level (High Level Trigger)  Farm with O (2000) multi-processor boxes  HLT1: Confirm L0 candidate with more complete info, add impact parameter and lifetime cuts  HLT2: global event reconstruction + selections High-Level Trigger 2 kHz Level -0 L0 e,  40 MHz 1 MHz L0 had L0  ECAL Alley Had. Alley Global reconstruction 30 kHz HLT1 HLT2 Muon Alley Inclusive selections ,  +track,  Exclusive selections Storage: Event size ~35kB LHCb Trigger  (L0)  (HLT1)  (HLT2) Electromagnetic70 % > ~80 %> ~90 % Hadronic50 % Muon90 % Trigger is crucial as  bb is only ~1% of total hadronic cross section and B decays of interest typically have BR < 10 -3

34. Andreas Schopper Calor 2008, 26-30 May 2008, Pavia Irina.Machikhiliyan@cern.ch Expected radiation environment EM component Hadronic component

35. Andreas Schopper Calor 2008, 26-30 May 2008, Pavia Irina.Machikhiliyan@cern.ch Behavior of module components under irradiation