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Gaseous detectors in CMSReadiness for operation at LHC

Armando LanaroU. of Wisconsin & INFN LNF

on behalf of the CMS Collaboration

IPRD08 Siena 1-4 October, 2008

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Intense magnetic field return flux through iron yokes

Hermeticity compact large detector surfaces

Detector modularity, handling, robustness, affordable

+

at LHC

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Clean final states 4µ (Higgs/SUSY search)

Muon system high resolution, high rate capability, radiation hardness, triggerable

Detector technology adapted to LHC requirements

=

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Gaseous

Muon Detector System

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system conditions

Barrel η<1.3

Particle rates < 10 Hz/cm2

Low magnetic field

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Endcap 0.9<η<2.4

Particle rates 100-1000 Hz/cm2

Punch-through ~100 Hz/cm2

High Magnetic field

Uniform axial >3T in η>2, z~5m Highly non-uniform radial field up to 1T in

iron yokes

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system requirements

Muons Trigger

Unambiguous BX identification

Trigger on single, multi-muons with

pt thresholds

between ~10 GeV to ~100 GeV

Momentum measurement

Charge assignment correct to

99% confidence level up to 7 TeV

Position resolution: <150 µm

Momentum measurement

Global momentum resolution(including inner Tracker)

∆p/p = 1 - 1.5% at p = 10 GeV∆p/p = 5 - 15% at p = 1 TeV

Alignment to <100 µm required

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Central BarrelDrift Tube Chambers (DT)

Resistive Plate Chambers (RPC)

Forward Endcap Cathode Strip Chambers (CSC)

Resistive Plate Chambers (RPC)

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Drift Tubes (DT)Barrel

250 Chambers, 180k channelsEconomical for use in low rate region

Large wire spacing long drift time slower response (<400 ns)

Good Resolution rΦ ~100 µm, Z ~150 µm, Angle ~1 mrad

Gas: Ar (85%) CO2 (15%)

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Cathode Strip Chambers (CSC)Endcap

468 chambers, 450k ch Close wire spacing fast

response good for high rates

Good spatial resolutionrΦ ~ 75 µm – 150 µm, < 2 mm at trigger level

4 ns timing resolution Gas: Ar (40%) CO2 (50%) CF4 (10%)

Trigger Track Finder Efficiency >99% per chamber

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Resistive Plate Chambers (RPC)Barrel & Endcap

1020 RPC Dedicated to first level trigger

Double gap (2mm) technology

Fast response, relatively inexpensiveGood timing resolution (<3ns)

spatial resolution rφ~1.5 cmGas: 95% Freon, 5% Isobutane

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Expected Standalone Muon Recon Expected Global Muon Recon(including inner Tracker)

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With B=4T objects deform!

(endcap yoke center bends-in by 16mm, edges out by 6mm)

Muon Alignment

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Option1: Photogrammetry of elements & detectors (B=0)

Excellent starting pointPrecision: ~1 mm rms

Option2: Optical system (analog/digital)Barrel+endcap+link global geometry

Reduce uncertainty to ~250 mm

Option3: Muon-track based alignmentRequires large/clean track samples

17Detector construction & assembly sites

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Production sitesCIEMAT AACHEN

LEGNAROTORINO

DT Production Sites

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PNPI

DubnaFermilab

IHEP

Dubna

Chamber with on-board electronics

CSC Production Sites

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Korea Pakistan

Cern ISR Test of first chambers

RPC Production Sites

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Installation at CERN - completed in October 2007

barrel

22endcap

23Detector commissioning with cosmic

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Local commissioning

Assess readiness of infra servicesDevelop diagnostic tools

Test detector functionalityMeasure efficiencies

Deploy timing proceduresValidate local reconstruction

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Global commissioning(w and w/o magnetic field)

Subsystem integrationSystem validation tests

DAQ, Trigger systems deploymentSynchronization

Global reconstruction

CMS

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September 10, 2008 12h30

First LHC Beam (450 GeV)

w/o RF- debunched after 250 turns

RF- wrong phase RF- wrong freq. RF – phase & freq OK

2 turns

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Wednesday, Sept 10 - CMS recording dataGigantic splash events observed when beam 1 sent onto collimator 150m

upstream of CMS. 100-1000 TeV deposited energy observed in ECAL-HCAL.

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~2.109 protons on collimator ~150 m upstream of CMSHB,HE: light blue - HO,HF: dark blue

ECAL: pink – Muon DT: greenTracker Off

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Events in barrel RPC

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ME−4ME−3ME−2ME−1

ME+1 ME+2 ME+3 ME+4

Beam Halo Events seen by CSC (beam through CMS)

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10-Sep-2008 10:30 Run 620642nd CMS run, with proton beam 1

First run with CSCs in, timed to beam

O u t l in e s o f C S C s in b lu eC S C s w it h h i t s in g r e e n - s t r ip s y e l lo w & w ir e s p u r p leR e c o n s t r u c t e d m u o n t r a c k in b lu e .

R e c o n s t r u c t e dR e c o n s t r u c t e dm u o n t r a c km u o n t r a c k

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Track polar angular distribution. Combination of beam halo & cosmic

rays.

CSC: single beam data

Un-normalized spectra

preli

minary

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September 19, 2008

During commissioning (without beam) of the final LHC sector (sector 34) at high current for operation at 5 TeV, an incident occurred at mid-day resulting in a large helium leak into the

tunnel. The implication of that is several months downtime for LHC operation.

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The CMS Muon system is complete and operated successfully for first LHC beam. All Muon subsystems took data and provided remarkable highlights of the first instants of beam operation.

... we’ll be back on stage soon!

2 reconstructed muons

11-Sep-2008 Run 62232 Event 1831882Beam 2 RF captured