Upload
claire-butler
View
216
Download
0
Embed Size (px)
Citation preview
Status & ReadinessStatus & Readiness of the of the
ATLAS Muon SpectrometerATLAS 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 AmericasWorkshop of the Americas
NYU August 4, 2009NYU August 4, 2009
Workshop of the Americas (NYU) – J. Chapman
Overview StatusOverview 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
Workshop of the Americas (NYU) – J. Chapman 3
OutlineOutline
• Very Quick Detector Description
• Sub-detectors Status
• Detector Control System Status
• Challenges to Precision Calibration
• Alignment System – next talk
• Commissioning Results
• Conclusions4-August-2009
Workshop of the Americas (NYU) – J. Chapman 4
ATLAS Muon SpectrometerATLAS 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 + 2nd coordinate– Thin Gap Chambers (TGC): trigger 1.05<|η|<2.4 + 2nd coordinate
• Performance goal: stand-alone Δp/p~10% at 1 TeV sagitta ~ 500 μm along measured with a resolution ~50μm
#chambers #channels Resolution (RMS)
MDT 1150 354k 35 μm (z&R) -
CSC 32 30.7k 40 μm (R) 3-7 mm (φ)
RPC 606 373k 10 mm (z) 5 mm (φ)
TGC 3588 318k 2-6 mm (R) 10 mm (φ)
4-August-2009
Workshop of the Americas (NYU) – J. Chapman
Spectrometer LayoutSpectrometer Layout
4-August-2009 5
Beam View
Side View
Muons cross 3 layers of precisionchambers for sagitta measurementTrigger chambers are placed onboth sides of middle precision layer (+ a few elsewhere)
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 TubesMonitored Drift Tubes
4-August-2009 6
Chambers in DAQ (2009)
Workshop of the Americas (NYU) – J. Chapman
MDT OccupancyMDT Occupancy
4-August-2009 7
MDT Occupancy – chamber Φ vs ηHot spots due to access shafts circled
1090/1150 Chambers installed – 99.6% operational
TGC vs MDT correlationLines ↔ noisy channels
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 InstallationEE Chamber Installation
4-August-2009 8
Workshop of the Americas (NYU) – J. Chapman4-August-2009 9
RPC StatusRPC 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)
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 PerformanceRPC Performance
4-August-2009 10
Workshop of the Americas (NYU) – J. Chapman
RPC Performance with MDT RPC Performance with MDT trackstracks
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 4th layer when trigger justified offline by 3 layers
113860
BM113860
From: G.Aielli
Workshop of the Americas (NYU) – J. Chapman4-August-2009 12
TGC StatusTGC Status• All chambers installed with final gas CO2: n-C5H12 (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
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 PerformanceTGC Performance
4-August-2009 13
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 StatusCSC Status
4-August-2009 14
Workshop of the Americas (NYU) – J. Chapman
• Knowing the drift time R-T function & offset t0.– Depends on gas temperature, composition, & pressure– Depends on pulse amplitude (time walk) & wire sag
– Depends on electronics delays & trigger timing (t0)
• Knowing the chamber alignment & B-field• Sensitivity figures:
– Drift velocity at wall is ~20μm/ns (50μm in 2.5ns)– t of 7oC corresponds to ~ 17ns ( many )– Wire sag for largest chambers ~ 500m– Plots for other variables visible in gas monitor
Securing & Maintaining Securing & Maintaining PrecisionPrecision
4-August-2009 15
Workshop of the Americas (NYU) – J. Chapman4-August-2009 16
MDT Detector Control SystemMDT 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: 7oCvariation frombottom to top!
T>25°C
T<18°C
Workshop of the Americas (NYU) – J. Chapman
MDT Gas Monitoring & PromptMDT Gas Monitoring & PromptCalibrationsCalibrations
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)
Workshop of the Americas (NYU) – J. Chapman
MDT gas Drift-time (TMDT gas Drift-time (Tmaxmax ) & Cavern ) & Cavern HumidityHumidity
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.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
Workshop of the Americas (NYU) – J. Chapman4-August-2009 19
MDT Calibration with Cosmic-raysMDT 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 t0-tuning algorithm.
• Dedicated L2 stream 3 centers for all chambers in 24h
• Collision data critical to obtain final precision
Residuals vs. Radiust0 fit
Workshop of the Americas (NYU) – J. Chapman4-August-2009 20
Segment Reconstruction PerformanceSegment Reconstruction Performance
Fall 2008<ε>=98.4%
Performance from clean sample:• No shower (#segments/event<20)• Track passing at least 2 stations• Extrapolation pass the 3rd station• Segment on each stationInner
layer
Outerlayers
For cosmic rayso enlarged single-hit error (1 mm)o relaxed matching angleo minimum 3 hits per segment
Efficiency(ε)= #Seg(found)/#Seg(expect)
Workshop of the Americas (NYU) – J. Chapman4-August-2009 21
Track ReconstructionTrack 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
Workshop of the Americas (NYU) – J. Chapman4-August-2009 22
Inner Detector vs. SpectrometerInner 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 theEloss compared with ID tracks
Δp(top-bottom)2 x 3 Gev lossin calorimeters
Workshop of the Americas (NYU) – J. Chapman4-August-2009 23
ConclusionsConclusions• 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 improveStill a lot of work to do, but the ATLAS Muon
Spectrometer is ready for beam
Backup SlidesBackup Slides
Alignment Issues
Workshop of the Americas (NYU) – J. Chapman
Layers, Locations, & LabelsLayers, Locations, & Labels
4-August-2009 25
EOEM
EI
Workshop of the Americas (NYU) – J. Chapman4-August-2009 26
Fake SegmentsFake 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 2008avg=1.1
Fall 2008avg=2.3·10-4
Workshop of the Americas (NYU) – J. Chapman4-August-2009 27
ATLAS Muon DetectorATLAS Muon Detector
Barrel |η|<1.05: I=inner, M=middle, O=outer layersof RPC + MDT in S=small and L=large sectors
Endcap 1.05<|η|<2.7three wheels (Small, Big, Outer) of TGC + MDT/CSC
Workshop of the Americas (NYU) – J. Chapman4-August-2009 28
MDT/CSC StatusMDT/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 OuterMDT occupancy
(Fall 08): sector vs. ηID
Workshop of the Americas (NYU) – J. Chapman4-August-2009 29
Precision Chambers AlignmentPrecision 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
Barrel Endcap
Workshop of the Americas (NYU) – J. Chapman4-August-2009 30
Barrel Alignment: Large vs. Small SectorsBarrel Alignment: Large vs. Small Sectors
Workshop of the Americas (NYU) – J. Chapman4-August-2009 31
Alignment in the BarrelAlignment in the Barrel• 105 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
Workshop of the Americas (NYU) – J. Chapman4-August-2009 32
Alignment in the EndcapAlignment 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)
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 μm– Separate optical alignment systems for barrel & endcap
complemented by alignment with tracks.
Spectrometer OverviewSpectrometer Overview
4-August-2009 33