1. Status & Readiness of the ATLAS Muon Spectrometer J. Chapman - University of Michigan on behalf of the ATLAS Muon Groups Particular Thanks to C. Ferretti, D. Levin, E. Diehl & A. Belloni (Harvard) Workshop of the Americas NYU August 4, 2009

2. Workshop of the Americas (NYU) – J. Chapman Overview Status 2 Hardware almost completed –Status at closure: –MDT Endcap fibers replaced –RPC nearing 95.5% coverage –TGC ready soon, after 7 months ATLAS DAQ functioning well –CSC working to reach design L1 rate Most data from 2008 runs Muon Sub-detector will be ready for collisions! 4-August-2009

3. Workshop of the Americas (NYU) – J. Chapman 3Outline Very Quick Detector Description Sub-detectors Status Detector Control System Status Challenges to Precision Calibration Alignment System – next talk Commissioning Results Conclusions 4-August-2009

4. Workshop of the Americas (NYU) – J. Chapman 4 ATLAS Muon Spectrometer Three stations in an air-core toroidal magnetic field (superconducting) (barrel: |η|<1.4, endcap: 1.6<|η|<2.7) Four different technologies: –Monitored Drift Tubes (MDT): precision chambers in the bending direction –Cathode Strip Chambers (CSC): precision chambers at |η|>2.0 –Resistive Plate Chambers (RPC): trigger |η|<1.05 + 2 nd coordinate –Thin Gap Chambers (TGC): trigger 1.05<|η|<2.4 + 2 nd coordinate Performance goal: stand-alone Δp/p~10% at 1 TeV  sagitta ~ 500 μm along  measured with a resolution ~50μm #chambers#channelsResolution (RMS) MDT1150354k35 μm (z&R) - CSC3230.7k40 μm (R)3-7 mm (φ) RPC606373k10 mm (z)5 mm (φ) TGC3588318k2-6 mm (R)10 mm (φ) 4-August-2009

5. Workshop of the Americas (NYU) – J. Chapman Spectrometer Layout 4-August-2009 5 Beam View Side View Muons cross 3 layers of precision chambers for sagitta measurement Trigger chambers are placed on both sides of middle precision layer (+ a few elsewhere)

6. Workshop of the Americas (NYU) – J. Chapman System features low failures –Readout channels: ~0.2% –T-sensors: ~0.3% –B-sensors: ~0.5% –Alignment: ~1-2% Final actions taken –Fiber replacement C & A side –Replaced a few faulty cards & sensors, sealed gas leaks –Switched barrel mezzanines to 50MHz & exchanged a few cards that did not operate successfully at higher speed Single-hit efficiency above 99% Hit resolution near design value Monitored Drift Tubes 4-August-2009 6 Chambers in DAQ (2009)

7. Workshop of the Americas (NYU) – J. Chapman MDT Occupancy 4-August-2009 7 MDT Occupancy – chamber Φ vs η Hot spots due to access shafts circled 1090/1150 Chambers installed – 99.6% operational TGC vs MDT correlation Lines ↔ noisy channels

8. Workshop of the Americas (NYU) – J. Chapman Additional MDTs –EEL Sector 5 installed –Mounted on Toroid Other sectors soon –EELA11 next –EELA14 follows Side C follows A –Schedule is uncertain EE Chamber Installation 4-August-2009 8

9. Workshop of the Americas (NYU) – J. Chapman4-August-2009 9 RPC Status 95.5% operative (out of 396 towers) < 4% broken HV connectors or electronic components < 1% leaky gas channels Temperature problem forces top sectors to run at 9.2kV (9.6kV)

10. Workshop of the Americas (NYU) – J. Chapman Cosmic data provides good evaluation of RPC –Hit efficiency in the high 90% region – expect the tails to be reduced with HV tuning –Resolution is as expected Timing calibration for trigger is underway RPC Performance 4-August-2009 10

11. Workshop of the Americas (NYU) – J. Chapman RPC Performance with MDT tracks 4-August-2009 11 Efficiency for BM chambers with HV=9.6kV, Vth=-1V BM Residual distribution normalized to strip pitch - Events triggered by RPCs with ¾ majority - Only 1 MDT track reconstructed by MuonBoy - Look at 4 th layer when trigger justified offline by 3 layers 113860 BM 113860 From: G.Aielli

12. Workshop of the Americas (NYU) – J. Chapman4-August-2009 12 TGC Status All chambers installed with final gas CO 2 : n-C 5 H 12 (55:45) Now: 3 chambers (less than 0.8‰) are problematic TGC trigger worked very well during DAQ periods Fall 2008 data TGC trigger timing

13. Workshop of the Americas (NYU) – J. Chapman Low rate of faulty channels –~0.02% in Middle Layer –~0.5% in Inner Layer –No holes in coverage L1 rate limited to 45kHz –Redundant information removed. Ready for tests Last runs (HV+gas) in 2008 –MDT/TGC work halted runs –Oil contamination of gas damaged vessel. System will be back mid August 2009 TGC Performance 4-August-2009 13

14. Workshop of the Americas (NYU) – J. Chapman 2 of 128 panels unusable –covered by redundancy New ROD firmware progress –Current status: max L1 rate < 1kHz; –ROD crashes after ~1k events fixed –Test stand & two SLAC engineers at CERN for redesign effort Commissioning the CSC with cosmics is difficult –Low probability to hit CSC –Only 50k events in 2008 with 199, 4-hit segments in CSC. CSC Status 4-August-2009 14

15. Workshop of the Americas (NYU) – J. Chapman Knowing the drift time R-T function & offset t 0. –Depends on gas temperature, composition, & pressure –Depends on pulse amplitude (time walk) & wire sag –Depends on electronics delays & trigger timing (t 0 ) Knowing the chamber alignment & B-field Sensitivity figures: –Drift velocity at wall is ~20 μ m/ns (50 μ m in 2.5ns) –  t of 7 o C corresponds to ~ 17ns ( many  ) –Wire sag for largest chambers ~ 500  m –Plots for other variables visible in gas monitor Securing & Maintaining Precision 4-August-2009 15

16. Workshop of the Americas (NYU) – J. Chapman4-August-2009 16 MDT Detector Control System The DCS provides initialization of the chambers and reads out –voltages/temperatures of ~18k F.E. electronic cards and power supply –over 13k temperature sensors –~2k Hall probes –gas parameters –alignment system –... Note: 7 o C variation from bottom to top! T>25°C T<18°C

17. Workshop of the Americas (NYU) – J. Chapman MDT Gas Monitoring & Prompt Calibrations 4-August-2009 16 Recycler gas supply line Track gas quality via maximum drift time Compare behavior of MDT gas for supply and exhaust lines Precision: below 1ns in the maximum drift time measurement, once/hour Universal Time-to-Radius (RT) relations published every two hours Gas volume exchange –Muon Spectrometer ~2 weeks refresh –Gas Monitor ~2 hours gas exhaust (D. Levin, N. Amram et al)

18. Workshop of the Americas (NYU) – J. Chapman MDT gas Drift-time (T max ) & Cavern Humidity 4-August-2009 18 ns Oct 2007 Dec 2008  t = 720-685ns = 35ns Monitoring TDC spectra continuously since August 2007 Results displayed at mdtgasmon.grid.umich.edumdtgasmon.grid.umich.edu Transients due to gas system interventions or occasional component failures Overall variation in maximum drift time caused by gas mixture change from –External humidity –Intentional water vapor injection

19. Workshop of the Americas (NYU) – J. Chapman4-August-2009 19 MDT Calibration with Cosmic-rays Difficult due to asynchronous nature of cosmic rays with LHC clock  25ns and variable TOF between trigger and precision chambers. Recovered by t 0 -tuning algorithm. Dedicated L2 stream  3 centers for all chambers in 24h Collision data critical to obtain final precision Residuals vs. Radius t 0 fit

20. Workshop of the Americas (NYU) – J. Chapman4-August-2009 20 Segment Reconstruction Performance Fall 2008 =98.4% Performance from clean sample: No shower (#segments/event<20) Track passing at least 2 stations Extrapolation pass the 3 rd station Segment on each station Inner layer Outer layers For cosmic rays oenlarged single-hit error (1 mm) orelaxed matching angle ominimum 3 hits per segment Efficiency(ε)= #Seg(found)/#Seg(expect)

21. Workshop of the Americas (NYU) – J. Chapman4-August-2009 21 Track Reconstruction MDT hits distribution peaked at 12, 14 and 20 (expected) Tails: overlap small-large sectors Track residual ~ 250 μm worse than segment residual (expected): - misalignment - multiple scattering Number of hits

22. Workshop of the Americas (NYU) – J. Chapman4-August-2009 22 Inner Detector vs. Spectrometer ΔP[GeV/c] Cosmic ray passing in the Inner Detector split in two tracks at the perigee. 3 GeV loss in the calorimeter. MS tracks corrected for the E loss compared with ID tracks Δp(top-bottom) 2 x 3 Gev loss in calorimeters

23. Workshop of the Americas (NYU) – J. Chapman4-August-2009 23Conclusions Hardware: status very good (nearing completion) Trigger: –Coverage much improved from 2008 –Timing between detector elements still being tuned Calibration: –Calibration centers returning constants in 36 hours –Fine tuning of constants awaiting collision data Alignment: Chamber position & orientation known Track segment finding, reconstruction efficiency, & resolution is improving & will continue to improve Still a lot of work to do, but the ATLAS Muon Spectrometer is ready for beam

24. Backup Slides Alignment Issues

25. Workshop of the Americas (NYU) – J. Chapman Layers, Locations, & Labels 4-August-2009 25 EO EM EI

26. Workshop of the Americas (NYU) – J. Chapman 4-August-200926 Fake Segments Form pattern recognition: 1 track should to give 1 segment/station From noise hits: study #segments far from the only track in the event Fall 2008 avg=1.1 Fall 2008 avg=2.3·10 -4

27. Workshop of the Americas (NYU) – J. Chapman4-August-2009 27 ATLAS Muon Detector Barrel |η|<1.05: I=inner, M=middle, O=outer layers of RPC + MDT in S=small and L=large sectors Endcap 1.05<|η|<2.7 three wheels (Small, Big, Outer) of TGC + MDT/CSC

28. Workshop of the Americas (NYU) – J. Chapman4-August-2009 28 MDT/CSC Status 1090/1150 MDT + 32/32 CSC chambers installed Shutdown: recovered ~7k MDT tubes, replaced MDT BW optical fibers, doubled speed for all MDT readout electronics Now: > 99.5 % MDT channels operational and 99.9% of the chambers are read by the ATLAS DAQ + 98.5 % CSC layers Work continuing on CSC readout Driver (ROD) firmware Inner, Middle and Outer MDT occupancy (Fall 08): sector vs. ηID

29. Workshop of the Americas (NYU) – J. Chapman4-August-2009 29 Precision Chambers Alignment Grid of ~12k optical sensors monitoring/reconstructing chamber position, rotation angles and deformations Track-based alignment used for global positions (Endcap Wheels-Barrel and Spectrometer-ID) After shutdown over 99% of the devices working and the degradation due to a few missing sensors is negligible BarrelEndcap

30. Workshop of the Americas (NYU) – J. Chapman4-August-2009 30 Barrel Alignment: Large vs. Small Sectors

31. Workshop of the Americas (NYU) – J. Chapman4-August-2009 31 Alignment in the Barrel 10 5 μ ± (20 GeV) enough to align at 30 μm (Small sectors: 5×statistics) Initial geometry + alignment traces displacement in relative mode Track + alignment parameters inside one global fit (correlations included) Tracks (magnetic field off runs) –Close to the IP (precision plane) –Traversing 3 stations –Straight line fit inner-outer MDT –Residuals in the middle chamber ~ sagitta = 22±7 μm

32. Workshop of the Americas (NYU) – J. Chapman4-August-2009 32 Alignment in the Endcap Corrected sagitta = 2±27 μm –3 segments tracks (EI-EM-EO) in the same sector –Angle segments-straight line EI-EO segments < 5/50 mrad (sagitta only) –At least 1 trigger phi hit (good 2nd coordinate measurement)

33. Workshop of the Americas (NYU) – J. Chapman Designed to trigger on and measure muons with Pt ≳ 3 GeV with resolution 3% < 250 GeV to 10% @ 1 TeV. Magnetic field from air-core torroids: barrel + 2 endcap Trigger detectors (trigger + 2nd coordinate measurement) –0< η <1.0 (Barrel) Resistive Plate Chambers (RPC) 373k chan –1.0< η <2.4 (Endcap) Thin Gap Chambers (TGC) 318k chan Precision detectors –0<η<2.0 Monitored Drift Chambers (MDT) 354k chan –Monitored ⇨ Positions monitored by an alignment system –2.0< η <2.7 Cathode Strip Chambers (CSC) 30.7k chan Alignment – determine chamber positions to ~50 μ m –Separate optical alignment systems for barrel & endcap complemented by alignment with tracks. Spectrometer Overview 4-August-2009 33