1. ATLAS Muon test beam, E. Etzion, NSS 2004 1 System Test of the ATLAS Muon Spectrometer in the H8 Beam at the CERN SPS Erez Etzion (Tel Aviv University), Stefano Rosati (CERN) On behalf of the ATLAS H8 Muon Test Beam Community IEEE, 2004 Nuclear Science Symposium Rome, Italy, October 17 2004

2. ATLAS Muon test beam, E. Etzion, NSS 2004 2 MUON Spectrometer To trigger on MUON’s, one needs: –Fast detectors to provide moderate Pt measurement and Bunch ID. –Azimuthal coordinate measurement for both, MUON tracking and correct the main tracking detectors. To track MUON’s with a precision similar or better than the ID, one needs: –Precision detectors, with deformations that can be followed – Precise magnetic field mapping – Alignment system over large distances, (relative position of chambers 30-40 microns.)

3. ATLAS Muon test beam, E. Etzion, NSS 2004 3 Monitored Drift Tubes The MDT chambers are made of two multilayers of pressurized aluminium drift tubes separated by 50 to 320mm high spacer and support structure. A multilayer consist of three (or four) layers of dense-packed drift tubes. Each tube determines the vertical distance between a charged particle track and the wire from the arrival time of the first ionization electron. Tubes: -outer diameter :30mm, wall thickness: 0.4mm; Wire:50  m(gold-plated) -370.000 channels Gas: -Ar:N2:CH4 -mixture (91:4:5) - pressure:3 bar(absolute) HV:3.25 kV

4. ATLAS Muon test beam, E. Etzion, NSS 2004 4 Cathode Strip Chambers Multiwire proportional chambers determine muon position by interpolating the charge on 3 to 5 adjacent strips Precision (x-) strip pitch ~ 5mm Measure Q1, Q2, Q3… with 150:1 SNR to get  x ~ 60  m. Second set of y-strips measure transverse coordinate to ~ 1 cm. Position accuracy unaffected by gas gain or drift time variations. Accurate intercalibration of adjacent channels essential. S = d = 2.54 mm W = 5.6 mm 32 four-layer chambers 2.0 < |  | < 2.7 |Z| ~ 7m, 1 < r < 2 m 4 gas gaps per chamber 31,000 channels Gas Ar:CO2:CF4 (30:50:20) High voltage :3.2 kV 32 four-layer chambers 2.0 < |  | < 2.7 |Z| ~ 7m, 1 < r < 2 m 4 gas gaps per chamber 31,000 channels Gas Ar:CO2:CF4 (30:50:20) High voltage :3.2 kV

5. ATLAS Muon test beam, E. Etzion, NSS 2004 5 Trigger Chambers The first level muon trigger is derived from three trigger stations formed of Resistive Plate Chambers (very fast detectors with moderate rate capabilities) in the barrel and Thin Gap Chambers (moderately fast detectors with high rate capabilities) in the end-caps. Each station is made of 2(or 3) planes of strips (or wires) with x or y readout. The trigger is based on a coincidence between a strip (or wire) hit in the 1 st station and a range of strips (or wires) in the 2 nd or 3 nd station. Typical momentum resolution is 20%.  Low p t trigger: p  >6GeV. High p t trigger: p  >20GeV.

6. ATLAS Muon test beam, E. Etzion, NSS 2004 6 Resistive Plate Chambers Resistive Plate Chambers are gaseous, self-quenching parallel-plate detectors. They are built from a pair of electrically transparent bakelite plates separated by small spacers. Signal are induced capacitively on external readout strips. - 420.000 channels in 596 double gap chambers. Gas: C2H2F4:isoC4H10 (97:3). HV : 9kV. Performance: -efficiency:>99%. -space-time resolution of 1cm1ns. -rate capability:~1kHz/cm². - 420.000 channels in 596 double gap chambers. Gas: C2H2F4:isoC4H10 (97:3). HV : 9kV. Performance: -efficiency:>99%. -space-time resolution of 1cm1ns. -rate capability:~1kHz/cm².

7. ATLAS Muon test beam, E. Etzion, NSS 2004 7 Thin Gap Chambers wires strips supports   -e +ion

8. ATLAS Muon test beam, E. Etzion, NSS 2004 8 Muon Test Beam setup BIL on rotating support CSC Magnet BOS MBPL TGCs Barrel Endcap

9. ATLAS Muon test beam, E. Etzion, NSS 2004 9 Barrel Stand 6 barrel MDT chambers (precision tracking) Fully instrumented with FE electronics, readout with 1 MROD Fully equipped with alignment system 6 RPC doublets (4 BML and 2 BOL) (LVL1 trigger + tracking) 1 Trigger PAD Being upgraded now to 2 PADS ( LowPt & HighPt) The setup is reproducing at full scale one ATLAS barrel sector with 6 MDT+RPC stations 2 additional barrel MDT chambers 1 BIL on rotating support for calibration studies 1 BOS station (MDT+RPC) upstream of muon wall for noise studies and CTB

10. ATLAS Muon test beam, E. Etzion, NSS 2004 10 BML BOL BIL - Rotating

11. ATLAS Muon test beam, E. Etzion, NSS 2004 11 Endcap Stand 11 MDT chambers (2 EI, 2EM, 2 EO) Fully instrumented with FE electronics, readout with 1 MROD Equipped with the complete alignment system (calibrated sensors for absolute alignment) Reproducing at full scale a muon spectrometer endcap sector 3 TGC chambers (2 doublets, 1 triplet) Fully instrumented with on-chamber electronics CSC : 1 chamber being installed during last week, should be integrated soon in the combined data taking

12. ATLAS Muon test beam, E. Etzion, NSS 2004 12 TGC Doublets TGC Triplet

13. ATLAS Muon test beam, E. Etzion, NSS 2004 13 Data collected until now A large sample of data has been collected since June Main tests performed on detectors: MDT LV tests in the ATLAS configuration (2 chambers/LV channel) Barrel alignment: large chambers rotations up to 8 mrad Endcap alignment: checks of sensors absolute calibration DCS – sensors, controls Noise and efficiency studies on a large scale (~1% of ATLAS) MDT-RPC cross talk studies MDT threshold scans RPC threshold and HV scans LVL1 trigger validation with TGC during the 25 ns run in June Muon system commissioning and integration Triggering during the muon standalone period with 10x10 or 60x100 cm 2 scintillators. Self-triggering with TGC or RPC during 25ns period Muon detectors are integrated in the Combined Test Beam data taking since mid of August

14. ATLAS Muon test beam, E. Etzion, NSS 2004 14 Online monitoring Channel vs Layer: Fast detection of Inefficiency and Noise Monitoring framework (GNAM) co-developed with the ATLAS Tile Calorimeter Data sampling at any level, Allow user libraries (decoding and histograms filling) Histograms published in the interactive presenter Monitoring in ATHENA Early studies algs and collected Monitor of Event Filter performance Online presenter (for both GNAM and EF-ATHENA)

15. ATLAS Muon test beam, E. Etzion, NSS 2004 15 Conditions DB CondDB DCS Temperature LV, B field Gas, CSM params Global Alignment Alignment End cap, barrel Run Parameters from DAQ IS ATHENA AMI Plot, Monitor PVSS interface to MySQL runs online and offline JTAG Use MySQL with dedicated interface software (MDT) or direct SQL (TGC) Nearly a complete loop of applications using the conditions data has been implemented All quantities needed are stored and read MDT - High rate access for raw alignment image results (~2 sec) TGC – Tested configuration via online and via DCS. Root, direct web access. Access from ATHENA analysis enviroenment under development.

16. ATLAS Muon test beam, E. Etzion, NSS 2004 16 Offline Software The ATHENA framework is used as offline monitoring, reconstruction and analysis tool Exploit the test beam data as test for the ATLAS software ByteStream converters: access to the raw data for all muon technologies (MDT, RPC, TGC, CSC, MUCTPI): same scheme as for ATLAS Preparing data using ATLAS Muon Event Data Model for: LVL2 (MuFast), EF (TrigMoore), offline (MOORE, Muonboy) algorithms Detector Description: same as for ATLAS (MuonGeoModel) Initialization from AMDB database primary numbers in NOVA DB, special AMDB version implemented for the CTB Using same DD for simulation and reconstruction (as in DC2) Offline algs (MOORE, Muonboy) as for DC and physics data Ntuples are produced with ATHENA for offline monitoring Useful tool for offline monitoring of detector performance Check events correlation among subdetectors Included in the Combined Ntuples Correlation Muon track InDet track

17. ATLAS Muon test beam, E. Etzion, NSS 2004 17 RPC preliminary results RPC efficiency can be evaluated comparing MDT segments extrapolation with the position of RPC clusters Tested cluster sizes and efficiecy for different HV and thresholds Tested correlation between MDT and RPC Efficiency vs HV and threshold Correlation MDT-RPC

18. ATLAS Muon test beam, E. Etzion, NSS 2004 18 TGC preliminary results TGC taking data during run with 25ns-bunched beam in June Validation of the design of the Endcap muon LVL1 trigger LVL1 trigger signal provided to the MUCTPI –Sector logic output and MUCTPI match perfectly DCS – operation and control Integration with the TGC conditions database Results on LVL1 trigger performance: –Low-Pt efficiency 99.4% –High-Pt efficiency 98.1% Correlation with MDT tracks

19. ATLAS Muon test beam, E. Etzion, NSS 2004 19 Beam momentum measurement Momentum GeV Mean=108 GeV Sigma=4 GeV Magnet OFF Magnet ON Exploit the bending in MBPL magnet upstream of barrel stand Reconstruction with MOORE Compare track angles in BIL upstream of MBPL and full barrel P=0.3BL/  BL=3.54 Tm

20. ATLAS Muon test beam, E. Etzion, NSS 2004 20 Beam momentum measurement Sigma – not tracking res. depends on collimators settings Energy loss due to material upstream of the muon area: calorimeters+3.2 m of iron (muon wall) Preliminary – MDT threshold 40 mV Sagitta Outer Middle Sagitta definition at the TB: Create r-z (MDT+RPC) and phi segments (only RPC), perform pattern recognition Segments fit on each station Combination of inner and outer, compare with middle station Misalignment affects mean value and width Multiple scattering affects width Nominal P(GeV) Measured P (GeV) Sigma (GeV) Sagitta resolution (  m) 10088.84.34102 120108.24.0694 150135.06.8478 180166.38.8373 220206.112.1166 250230.015.1162

21. ATLAS Muon test beam, E. Etzion, NSS 2004 21 Comparisons with G4 simulation Real data/G4 sim reconstruction comparison provides important feedback to the G4 validation effort First tests: generate muons in the CTB setup (only muon detectors activated for now) at beam energies measured in data Reconstruction with MOORE Compare fit residuals and sagitta resolution Data  =61  m G4  =57  m MDT fit residuals Data G4 Athena 8.8.0 Sagitta width

22. ATLAS Muon test beam, E. Etzion, NSS 2004 22 Results on alignment corrections Tests of the relative alignment system: perform chambers controlled movements and correct using the information from the optical alignment system – many tests successfully performed during 2003 test beam Results shown here are from barrel controlled movements performed during 2004 data taking (rotations about X axis – beam axis) Reconstruction with Muonboy in ATHENA Rotations at the limit of the dynamical range of the alignment system (~8 mrad) Absolute alignment is being validated (sensors calibrations) Similar studies ongoing for the endcap system

23. ATLAS Muon test beam, E. Etzion, NSS 2004 23 Conclusions The muon test beam has profited of many years of tests and experience of the muon group in H8 Many aspects of detectors integration and combined data taking have been tested Data taking is going on since June, Shown here: Detector and trigger performance Detector operation and control Use of the offline software framework (ATHENA) Reconstruction algs. studies Comparisons of G4 simulation with real data Alignment Further studies: Another run with 25 ns bunched beam (2 weeks ago) RPC and TGC LVL1 trigger Complete the integration of the muon trigger slice (LVL1-LVL2-Event Filter) Alignment of the muon system Combined data taking Combined alignment, reconstruction and physics studies

24. Thank you