CMS muon detectors and muon system performance Physics goals Muon system layout Barrel Drift Tubes Chambers (DT) Endcap Cathode Strip Chambers (CSC) Resistive Plate Chambers (RPC) Muon system performance Ezio Torassa – Sez. INFN di Padova LHC days in SPLIT – SPLIT (Croatia) – October 4-7 th 2000 E. Torassa

Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000 Physics goals The 4 lepton channel is crucial for the discovery of the SM Higgs boson Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000 Physics goals H g Z Z(*) g 4 m SM Higgs (mass resol. ~ 1 GeV) h, H, A g m+ m- SUSY Higgs q , g g multi-lepton + multi-jet + Etmiss Superpartners (muon recognition in multi-jet environment) Z’ g m+ m- New Gauge Bosons (Pt m measur. and sign determ. Above 1TeV) etc … ~ ~ Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000 Muon system layout E. Torassa Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000 Muon system layout Barrel (h<1.3) DT - RPC particle rates < 10 Hz/cm2 low B field < 0.8 T Endcap ( 0.9<h<2.4) CSC - RPC particle rates 10-100 Hz/cm2 high B field up to 3 T Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000 Muon system layout DT goals Measure f and z points along muons track segements in the barrel region to: identify muons and measure charge and momentum identify the bunch crossing associated to every muon track CSC goals Like DT but in endcap regions RPC goals Measure f points along muons track segements in the barrel and endcap regions to: identify muons and assign a bunch crossing to the tracks estimate their pt Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Barrel Drift Tubes Chambers 172200 Anode ch. Superlayer Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Barrel Drift Tubes Chambers Cell designed to have electric field as uniform as possible ò Drift velocity mm/ns Gas mixture Ar/CO2 ( 85/15 % ) Vc / Vs / Vw = -1.2/+1.8/+3.6 (kV) ò E = 1 - 2 kV/cm Electric field kV/cm Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Barrel Drift Tubes Chambers DT performance Results from July 1999 CERN-H2 test beam The prototype is a narrow MB2 type superlayer with the final cell design Single cell s ~ 170 mm Single cell efficiency ~ 99.8 % Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Barrel Drift Tubes Chambers DT performance in magnetic field Bz Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Barrel Drift Tubes Chambers DT trigger BTI front-end device TRACO device Bunch and Track Identifiers: Synchronous device with 80 MHz FIFO unit, it stores times with 12.5 ns resolution Track Correlator TMEAN = T MAX is independent to the angle and the position of tracks Output: x, y, TRGLEVEL Output: X, Y, CORR/TRGLEVEL The clock count identify the bunch crossing Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Endcap Cathode Strip Chambers 4 disks 2-3 rings (3 for ME1) ~ 2.5 million wires 210816 Anode ch. 273024 Cathode ch. (*)(ME4 staged) Chamber Trapezoidal shape covers 10o or 20o sectors Each Chamber has 6 gas gap planes Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Endcap Cathode Strip Chambers CSC gas gap plane is a multiwire proportional chamber H.V. wires 3.6 kV (Qcath. ~ 110 fC, Qanode ~ 140 fC) 3.2 mm 9.5 mm Wires measure r-coordinate Wires spaced by 3.2 mm ganged in groups of 5-16 Wires group width 16-51 mm (digital readout) Strips run radially to measure f coordinate 3 - 16 mm Strips width 3-16 mm (analog readout) Gas mixture Ar/CO2/CF4 ( 40/50/10 % ) Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Endcap Cathode Strip Chambers CSC performance Strips Single layer efficiency ~ 100 % Single layer resolution ~ 50 mm Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Endcap Cathode Strip Chambers CSC performance in magnetic field Br < 1 T |f| < 6o s < 150 mm s ~ 60 mm Bz < 3 T Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Endcap Cathode Strip Chambers CSC trigger Comparator device Cathode Local Charged Track Processor thresh Latch Latch Position Angle Bunch crossing ident. ò 4 comparators localize hits to within a half-strip Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Resistive Plate Chambers RPC MB RPC ME 360 Stations 252 Stations (6 shells , 12 sectors) (4 disks , 1 or 3 rings) 80640 strips 92162 strips FEB ME2 Strip orientation MB2 MB1, MB3, MB4 Strip orientation 30o AL bars Each station has 2-3 double-gap modules Chamber Trapezoidal shape covers 10o or 30o sectors RPC ME2 station has 6 double-gap modules Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Resistive Plate Chambers RPC double gap module Avalanche created inside the gap, charge induced on strips Electrode resistivity ò Rate capability ò Gap width Time performance Avalanche operation mode (higher rates w.r.t. streamer mode) Operating H.V. 8.5 - 9.0 kV Gap width 2 mm Bakelite bulk resistivity 1-2 1010 W cm Bakelite thickness 2 mm strip width ~ 35 mm Gas 95% C2H2F4 , 5% i-C4 H10 Double gap improves efficiency and time resolution Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Resistive Plate Chambers RPC performance Trigger efficiency Trigger efficiency s < 3 ns Efficiency ~ 100 % RPC time resolution (ns) RPC efficiency Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Resistive Plate Chambers RPC trigger Pattern comparator trigger device Because of energy loss fluctuations and multiple scattering there are many possible patterns in RPC chambers for similar muons The PACT electronic performs two functions: requires time coincidence in 3 or 4 stations compares hits to predefined patterns for muons of various momentum (obtained from simulation) Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Muon system performance Muon Identification Precision dpt/pt for pt<100 GeV Charge assignment correct to 99% confidence Unambiguous bunch crossing identification Requirements Muon system with inner tracker dpt/pt ~ 1 % Muon system with vertex constraint dpt/pt ~ 10 % Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Muon system performance Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Muon system performance Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000 Conclusions Madrid MB2: glue on top of 1st layer of I-bemas Legnaro table for MB3 q SL FNAL CSC wire winding station FNAL CSC assembling station Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000

Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000 Conclusions CMS muon system is designed to achieve the LHC physics goals Required performances were obtained with tests of detector prototypes Mass production of chambers has begun Ezio Torassa - LHC days in SPLIT - October 4-7 th 2000