HEP 2007 – 20 Jul 2007 · Manchester, England Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer F.Petrucci INFN Sezione di Roma Tre and Dipartimento di Fisica, Università Roma Tre On behalf of the ATLAS Muon Collaboration

2 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 2 Summary   The ATLAS Muon Spectrometer   Status of the installation   Commissioning   First results from commissioning in the pit   Conclusions

3 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 3 MDT chambers in the ATLAS Muon Spectrometer The research program of the ATLAS experiment at the Large Hadron Collider requires the detection of photons, electrons, hadron jets, missing energy and muons with good momentum resolution over a large acceptance.  3 large toroidal magnets (two end-cap and one barrel). Bending power ∫Bdl~3 T∙m in the barrel region and ~6 T ∙m in the endcap.  3 tracking stations (Inner, Middle and Outer) in 8 Large sectors and 8 Small sectors  Muon tracking detectors:  good space resolution (~80 μm per point)  robust and reliable operation for many years.  Dedicated trigger detectors that also measures the second coordinate. Muon momenta are measured with large toroidal magnets and tracking is done in air.

4 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 4 Trigger chambers: RPC Planes of 2 overlapping units. 2 gas gap and 2 planes of readout strips (  ) per unit. Saturated avalanche regime. Thin Gap Chambers (TGC) Multiwire proportional chambers in saturated mode. High Rate Capability. (  ) readout: wires and cathode strips Detectors Precision chambers: MDT (Monitored Drift Tubes) Two multilayers of staggered 3 cm diameter drift tubes. Gas mixture, 93%Ar−7%CO2, absolute pressure of 3 bar. Single point resolution ~80  m, drift time 700 ns. Low gas gain of 2×104 to avoid ageing effects. CSC (Cathode Strip Chambers) proportional wire chambers with cathodic strips. Single point resolution ~60  m; drift time ~30 ns

5 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 5 Installation Barrel spectrometer TGC wheel Endcap toroid

6 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 6 Installation (2) Barrel   Installation:   695/704 stations installed.   Missing few chambers in feet and lower sectors to permit Big-Wheels opening and access to the inner part of the detector.   Positioning:   Very well advanced (~95%). Mainly limited by interference with ID-Calo services. Endcap   6 out of the 8 Big Wheels installed: 4 BW sector C + 2 BW sector A (TGC1 and MDT1).   The 2 Small Wheels ready in Oct/Nov, the EO Wheels still missing (but all chambers are ready) Magnets   Barrel toroid: installed and tested   Endcap toroid: both EC toroids installed in June and July

7 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 7 Commissioning A level-by-level strategy was adopted :   Level I: Test of each station done on surface before installation   MDT tested for:   HV test, gas leak tightness, DCS functionality   Read-out via Test Pulse Runs   RPC tested for :   Leak tightness, Noise level   LVL-1 read-out via Test Pulse Runs   Level II: check basic functionalities with provisional services of the stations after installation in the cavern. Done for most of the stations.   DCS, FE electronics, noise runs   HV and gas leak tightness   Level III: check full functionality and sign-off of complete sectors (to be done with final services, power supplies and RO eltx) After level III full sectors are ready to be integrated in ATLAS

8 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 8 Commissioning (2) Status and plans:   Started from top sectors.   Finalize sectors 5 and 6 (partially commissioned)   Move to sectors 3–4 in August/September. Then sectors 1-2, 7-8, … Output of the level III sector commissioning:  Check general functionalities of single detectors.  Commissioning of power and DCS systems sector by sector.  Commissioning of sector alignment system.  List of dead and noisy channels.  Check of gas distribution.  Full test up to cosmic ray run  Fix of left over problems  Check/filling of the configuration DB for later use.

9 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 9 9 Sector 13 Sector 5 Sector June ’07 data taking period:  85 chambers:  71 Barrel MDT (sect. 5+6, side A+C) + 14 Endcap MDT (BW sect. 10, 11, 12). Apprx mdt tubes read-out.  No magnetic field  RPC trigger  Sector 5 side A  Fully operational alignment system  Services  MDT Gas: Barrel: recirculation mode (800lt/h) EC: open gas flow  LV-HV : power supplies and control system in final configuration November ’06 runs  Barrel Toroid at full field (20.5 kA nominal current reached at first cool down)  13 MDT stations (2% of the barrel) in sectors 12,13,4, side A  RPC trigger  Muon Barrel Alignment (15% of barrel system) First results from Barrel commissioning in the pit

10 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 10 First results from Barrel commissioning in the pit PX 14 D=18 m SX 1 Y Z PX 16 D=12.6 m 60 m 35 m 15.9 m 53 m Cosmic rays mainly form the shafts.  RPC trigger in Sector 13 side A. Measured rate: 5 Hz/m 2  Cosmics tracks from both shafts.  RPC trigger in Sector 5 side A. Mesured rate: Hz.  Cosmic tracks from PX14.

11 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 11 Runs with magnetic field (November ’06 runs)

12 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 12 Runs with magnetic field (November ’06 runs)  Clear separation of  + and  -  Angular distribution consistent with geometry (two peaks correspond to near and far access shafts)  Momentum spectra consistent with expectations  Ratio  + /  - ~ 1.5 Find more details on the simulation of cosmics in the presentation by Thijs CORNELISSEN.

13 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 13 Commissioning sectors 5 & 6 (June ’07) MDT hit map (example of one layer of a middle station in run 11533). Check dead/noisy tubes, trigger coverage,…   No trigger in eta region 5 in this run. The angle of incidence of the track segments and its dependence on Z coordinate (along the beam line) are consistent with cosmic tracks coming from the main shaft. Tube number ~10 m (half a sector length)

14 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 14 Commissioning sectors 5 & 6 (June ’07) Drift time parameters (MDT chambers test)   All t 0 ’s within a chamber are very close, as expected. t0t0 t max  Spectrum length (t max -t 0 ) is an estimator of drift properties. Spectrum length distribution for all the chambers is good.  One chamber with a much shorter spectrum (closed gas valve). mezzanine number Time (ns)

15 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 15 MDT space-time relation Space-time relations are computed in each MDT chamber with an auto- calibration procedure.   All r(t)’s for the chambers in sector 5A in a run in June `07 are within 30  m. Black = Magnet OFF Red = Magnet ON BIL3A13 Multilayer 1 Rt(Magnet Off) - rt(Magnet ON)  A measurement of the effect of magnetic field on r(t) relations has been performed during november runs with the magnet on. It is taken into account in the calibration procedure.  r(t) (mm) Time (ns)  r(t) (mm)

16 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 16 RPC efficiency and correlation with MDT Measurement of RPC efficiency with two independent methods:  Use only RPC information (RPC self-tracking).  Extrapolate MDT tracks in the RPC (MDT Tracking). Systematics are under investigation, the two methods are consistent and a good correlation between the detectors is shown. BML Confirm: inner RPC planes. BOL Confirm: outer RPC planes. Each point refers to two contiguous gas gap in η. Only η view can be used in coincidence with MDT. Thanks to the University and INFN groups of Roma Tor Vergata and Lecce

17 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 17 Conclusions   The installation of the barrel ATLAS muon spectrometer is finished. The endcap is well advanced.   The magnet system has been installed and the barrel toroid already tested at nominal current.   Sector commissioning of the spectrometer started.   Overall good behaviour of the chambers tested so far.   Trigger system, DCS, Alignment and DAQ systems well advanced.   Combined runs taken with the calorimeters.   We are working to have the full system commissioned and ready to be integrated in ATLAS... … many thanks to all the people involved in installation, DAQ, DCS, alignment, offline and online software for their efforts (the list is too long!)

18 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 18 BACKUP SLIDES

19 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 19  two multilayers of 3 (in Middle and Outer rings) or 4 (in the Inner ring) layers of staggered drift tubes each.  thin wall (400 μm thick) 3 cm diameter aluminum tubes.  Gold-plated W-Re anode wire, 50 μm diameter is tensioned at 350 g crimped in copper pins.  low longitudinal diffusion gas mixture, 93%Ar−7%CO 2, absolute pressure of 3 bar.  low gas gain of 2×10 4 (3080 V andode voltage) to avoid ageing effects. MDT chambers

20 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 20 RPC  Planes of 2 overlapping units. 2 gas gap and 2 planes of readout strips (  ) per unit.  Electrodes: graphite layer +2 mm Bakelite plates.  Gap gas: d = 2 mm, surface =1.72×0.75m 2 ÷ 2.96x1.2m 2.  Saturated avalanche regime C 2 H 2 F 4 (94.7%)C 4 H 10 (5%)SF 6 (0.3%), atmosferic pressure, HV~10 KV  Rate Capability ~ Qintegrated=0 > Qintegrated=210mC/cm2 = 7y LHC x 5 (Safety Factor) Trigger chambers Thin Gap Chambers (TGC)  Multiwire proportional chambers  2-D information: wires and cathode strips  Wire spacing: 1.8 mm, anode-cathode gap: 1.4 mm  50  m W anode wires  C0 2 /n-Pentane 55/45 in saturated mode  High Rate Capability

21 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 21 ATLAS RPC CHAMBERS Muon Barrel Spectrometer: LV1 RPC trigger   Pivot Hit Coincidence Window (Low Pt plane) Coincidence Window (High Pt Plane)  Identify  `s candidate tracks  On-detector trigger/readout electronics: Coincidence Matrix ASIC’s (CM)  Assign bunch crossing number (25 ns)  Select Region of Interest:  x  x   Programmable Pt thresholds   and  view trigger   second coordinate (pitch ~3 cm)

22 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 22 Alignment System - Barrel   5817 sensors in total   MDT inplane system monitor chamber deformations O(1)  precision   Proximity and Axial system align chambers within layer 10  precision   Projective system align chambers within sector 30  precision   Chamber-Chamber-Connect. System align small sectors to large 200  precision   Reference system absolute alignment 500  precision

23 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 23 Alignment system - EndCap   6416 sensors in total   Reference grid of monitored alignment bars - Internal optical straightness sensors - Temperature sensors   Polar sensors align bar to other wheel   Azimuthal sensors align bars within wheel   Planarity sensors align chamber to chamber   Proximity sensors align chamber to bar and align chamber to chamber   Inplane sensors: MDT chamber deformations

24 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 24 Cosmic rate high enough for polar angles up to 75 o : ~1Hz/strad for muons going through the ID (almost projective) and p m >10GeV => Study of all barrel sectors except sectors 1-9 Acceptance could be extended to sector 1-9 and part of the EI/EM end cap chambers by using non pointing tracks:

25 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 25 Black = Magnet OFF Red = Magnet ON Black = Magnet OFF Red = Magnet ON r-t(Magnet Off) - r-t(Magnet ON) RT Relations – B-field effect

26 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 26 RT Relations – B-field effect

27 HEP 2007 – 20 Jul 2007 · Manchester, England Fabrizio Petrucci Commissioning with Cosmic Rays of the ATLAS Muon Spectrometer 27 Particle background in ATLAS Total flux ~ 5 kHz/cm 2 (safety factor 5 applied to account for errors in simulations) MDT sensitivity   to neutrons ~ 5 ∙10 -4   to photons ~ 8·10 -3 Chambers have to operate in the harsh LHC background for about 10 years. Moreover, possibility for an upgrade for S-LHC (10 times higher luminosity). 10 years of ATLAS operation at LHC: 1) Integrated charge : 0.6 C/cm 2) Neutron integrated flux : 3.45 ∙10 11 n/cm 2 (Inner Barrel region) SLHC project : 10 times higher fluxes than LHC for 10 years. Fluxes (kHz/cm 2 ) NeutronsPhotons L=10 34 cm -2 s -1 Low energy secondary particles (charged particles, neutrons and photons in the MeV range) from hadron interactions with detector and machine elements. Uncorrelated to primary p-p collisions.