Presentation on theme: "Commissioning with cosmic rays of the Muon Spectrometer of the ATLAS Experiment at LHC Luca Spogli Università Roma Tre & INFN Roma Tre LNF Frascati Spring."— Presentation transcript:
Commissioning with cosmic rays of the Muon Spectrometer of the ATLAS Experiment at LHC Luca Spogli Università Roma Tre & INFN Roma Tre LNF Frascati Spring School 2007
2 Outline The ATLAS experiment at LHC Muon Spectrometer Commisioning Status Test with cosmic rays Summary
4 good space resolution (~100 μm per point) p t /p t p t <200GeV/c p t /p t p t 1TeV/c MDT (Monitored Drift Tubes) Tubes per layer Layer per multilayer Chamber lenght (mm) Chamber heigth (mm) ~1200 chambers / ~7000 m 2 MDT RPC TGC CSC ECT =1 =1.4
5 MDT Calibration: r(t) Drift time measurement Determination of space-time relationship r(t) via autocalibration Time measurement rt-relation with a typical accuracy of 10µm
6 Muon Reconstruction MDT mutilayer In a single multilayer Track segments Momentum measurement from sagitta determination p=0.3 Br
7 Installation and commissioning Installation in the pit started in Summer 2005 First tests with cosmic muons during Summer 2006 First curved muon (magnetic field on) in November 2006 MDT chamber installation completed in the barrel region
8 Installation It is not an easy task... It is not an easy task...
9 Cosmics November data Sector 13 with RPC timing informations Magnetic field on-off ~1 Mevents 9 chambers Many tests on MDTs Drift behavior Calibration Efficiency Noise Dead channels Preliminary alignment Some results in this talk Sector 13 Side A
10 Event Display BIL chamber
11 Fired tubes per event Accidental trigger coincidences 6 multilayers 4 multilayers 2 multilayers Number of Fired Tubes / event...after noise reduction cuts
12 Impact of magnetic field on r(t) B field parallel to the wire Electrons do not travel straight forward radially They travel under an angle ψ Drift time t for a certain radius r increases B field expected to change drift-to- radius relationship by Lorentz angle τ : mean time between collisions
13 µ- µ+ Ratio of µ+ / µ- = 1.48±0.27 Measured muon spectra Momentum (GeV) According to P.D.G Charge ratio of cosmic ray muons is between from 1 to 100 GeV Effects of geometrical acceptance have to be taken into account Z coordinate Big shaftSmall shaft
14 Big shaft ~18 m Small shaft ~12 m SIDE A SIDE C Surface-Pit ~100m Sector 13 Side A Muons coming from the shafts, are deviated in the upper part of Muon Spectrometer before ending in sector 13; due to the magnetic field µ+, µ- result in different angles.
15 Conclusions Barrel installations is completed Test with cosmic muons: complete analysis of sector 13 data Systematic study of the MDT performance over the all barrel sectors (magnetic field off) Further tests with cosmics in June with B field on.
16 Backup slides...
17 Energy per Proton7 TeV Bunch spacing25 ns Bunch size 15 m 12 cm Protons per bunch10 11 Bunches per ring2835 Beam mean life10 hours Project Luminosity10 34 cm -2 s -1 Circumference27 Km Collisions per bunch25 Detection of Higgs decay final states: H ZZ 4 µ Golden Channel 114.1GeV < m H < 1 TeV
18 two multilayers of 3 (in Middle and Outer rings) or 4 (in the Inner ring) layers of staggered drift tubes each. 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. thin wall (400 μm thick) 3 cm diameter aluminum tubes. low longitudinal diffusion gas mixture, 93%Ar7%CO2, absolute pressure of 3 bar. low longitudinal diffusion gas mixture, 93%Ar7%CO2, absolute pressure of 3 bar. Gold-plated W-Re anode wire, 50 μm diameter is tensioned at 350 g crimped in copper pins. Gold-plated W-Re anode wire, 50 μm diameter is tensioned at 350 g crimped in copper pins. low gas gain of 2×10 4 (3080 V andode voltage) to avoid ageing effects. low gas gain of 2×10 4 (3080 V andode voltage) to avoid ageing effects. good space resolution (~100 μm per point) robust and reliable operation for many years (no ageing problems). MDT (Monitored Drift Tubes) From F.Petrucci Tubes per layer Layer per multilayer Chamber lenght (mm) Chamber heigth (mm) ~1200 chambers / ~5500 m 2
19 Impact of resolution Space resolution ~100 micron Transverse momentum resolution Z mass resolution (combined with Inner Detector tracking) Z->µµ From TDR Invariant Mass (GeV)
20 ATLAS Installation Schedule 9.1
21 Setup 13 Muon stations read-out BIL BML BOL BOF BIL 1 BIL 3BIL 2 BOF1 BOF3 BML 3 BOL 3 Side A From R. Nikolaidou
22 TDC vs ADC spectrum Noise Signal ADC counts TDC counts Background double hits When a tube has a second hit in the same event. From C.Bini
23 Magnetic field map Magnetic field strongly inhomogeneous, in particular in BILs! From C.Bini
24 Angle of tracks µ- µ+ degrees Angle of tracks with respect to vertical axis. Shift in spectrum for different signs (run with magnetic field on) Muons coming from the small shaft Big shaft µ+µ- Angle of tracks: superposition of run with and without magnetic field µ- µ+ run with magnetic field on µ run with no magnetic field From R. Nikolaidou