The CMS muon system

The CMS muon system

Borislav Pavlov

(University of Sofia “St. Kliment Ohridski”)

for

the CMS Collaboration

6th BPU Conference B. Pavlov Istanbul, 22-26 August 2006

Introduction

Introduction CMS Muon System DT CSC RPC Moun Trigger Summary


CMS: design & construction

Muon System

CMS


System Conditions & Requirements

Barel < 1.3

Particle rates < 10 Hz/cm2

Low Magnetic field

Endcap 0.9 < < 2.4

Particle rates 100-1000 Hz/cm2

Magnetic field

Uniform axial > 3 T in ME1/1

Highly non-uniform radial field

Up to 1 T in ME1/2

Muon identification Muon Trigger

Unambiguous BX identification Trigger single and multimuon with well

defined pt thresholds few GeV to 100 GeV

Muon momentum measurement Charge assignment correct to 99%

confidence level up to 7 TeV Momentum resolution

Stand alone

dpt/pt = 8 - 15% at pt = 10 GeV

dpt/pt = 20 - 40% at pt = 1 TeV Global

dpt/pt = 1 - 1.5% at pt = 10 GeV

dpt/pt = 6 - 17% at pt = 1 TeV

System Conditions Requirements


Reduced RE system|| < 1.6

1.6

ME4/1 restored

MB1

MB2

MB3

MB4

ME1ME2 ME3

¼ longitudinal slice

CMS Muon System


Requirements

Resolution (per station)

Position R : 100 m Z : 150 m Angle: 1 mradBX identification Efficiency

>98% per station

Drift Tubes - DT Cathode Strip Chambers - CSC

Spatial resolution () (per station) 75 m ME1/1 and ME1/2 150 m for the others

(At the trigger level < 2mm)Correct BX identification

> 92% per chamber ( 99% global)

Trigger Track Efficiency >99 % per chamber

BARREL ENDCAP

Resistive Plate Chambers - RPC

(Dedicated Trigger Detector) Good timing : Resolution < 3ns (RMS), 98% within a 20ns window Good Rate capability Low cluster size High efficiency > 90% per chamber ( 95% global) r resolution ~ 1cm


Drift Tube Chambers

MylarMylar

Electrode Electrode StripStrip

Cathode Al Strips

Wire

42mm

13 mm

GASGAS: Ar/CO2 (85/15))

HV: HV: Wires 3600 V Strips 1800 V I-beams -1200 V

Tmax: Tmax: 380 ns Single Wire Single Wire 100m Drift Velocity :Drift Velocity : ~ 55m/ns Resolution : Resolution : < 300 m 150m

4 Layers = 1 4 Layers = 1 SuperlayerSuperlayer (SL) (SL)

Independent SubunitIndependent Subunit

(Gas tightness, HV, Front End)

SL SL

Honeycomb SL


DT Local trigger - Bunch Track Identifier (BTI)

Based on meantime technique

MT is independent on the track angle and position

MT1 = 0.5 * (T1 + T3) + T2MT2 = 0.5 * (T2 + T4) + T3

Signals are shifted in registersBTI looks for coincidence every clock period

hits in ≥ 3 planes At a time T=Tmax after muon crossing the drift times are aligned i.e. the hits form an image of the muon track

Allows effective bunch crossing identification


Barrel Muon DT

1

4

2

35

6

7

89 10

11

12

60 MB1 3SL 2 RPC ~2.0 x 2.54 m2 960kg60 MB2 3SL 2 RPC ~2.5 x 2.54 m2 1200kg60 MB3 3SL 1 RPC ~3.0 x 2.54 m2 1300kg

40 MB4 2SL 1 RPC ~4.2 x 2.54 m2 1800kg

10 MB1 2SL 1 RPC 10 MB2 2SL 1 RPC10 MB3 2SL 1 RPC

The Barrel Muon system comprises 250 chambersIn 7 flavors for 5 wheels Total 1700 m2


Production sitesCIEMAT AACHEN

LEGNAROTORINODT Production

Sites


Cosmic Event in a CMS sector


Magnetic field = 1T Cosmic muon trajectory in the barrel DTs

http://cms.cern.ch/


Cathode Strip Chambers (CSC)

Gas:Ar(40%) + CO2 (50%) + CF4(10%)

Gas gap 9.5mm

Wire spacing ~3mm

HV wires ~ 3.6 kV

Trapezoidal Chambers (100 or 200 in ), 6 layers

Radial cathode strips – measure (75-150 m)

Wires orthogonal to strips

Precise timing measurement (BX) - ~4.5 ns

Coarse measurement of the radial position (16-54 mm)


CSC

ME1/1 –special design

Inserted in endcap

Calorimeter support

Outer section of 4’th station staged

6 planes per chamber

468 chambers

6000 m2 sensitive area

2 Million wires

220 K cathode channels

1 chamber ~ 1000 readout chanels


PNPI – 114 assembled

DubnaFNAL – 148 assembled

IHEP – 148 assembled

Dubna – 72 assembled

Chamber with on-board electronics


ISR FAST Site

Final Testing before installation at SX5


YE+1 YE-1

14 June, 2006CSCs on YE+1 and YE-1


Cosmic Ray

using test pulses and cosmic rays

First particles detected by installed “CMS” subsystem!!

Chamber commissioning at SX5


Resistive Plate Chambers

Resistive PlatesResistive Plates – – bakelite with bulk bakelite with bulk resistivity (2 ± 1).resistivity (2 ± 1).10101010ΩΩcmcm

Gas gapGas gap ( (2mm ± 202mm ± 20μμm widem wide) )

Gas mixtureGas mixture, containing , containing

96% C96% C22HH22FF44(Freon), (Freon),

3,5 % isobutan, SF3,5 % isobutan, SF66 – 0,5 % – 0,5 %

Graphite electrodesGraphite electrodes with resistivity with resistivity 300 k300 kΩΩ / cm / cm

Insulating PET filmInsulating PET film ( (0.3 mm thick0.3 mm thick))

Detecting copper stripsDetecting copper strips

4040μμm thick,2–4 cm wide and 1250 m thick,2–4 cm wide and 1250 mm longmm long

Spacers (Spacers (cylinders withcylinders with

diameter 10 mm and height 2mmdiameter 10 mm and height 2mm))

Copper shielding Copper shielding

Linseed oil treatmentLinseed oil treatment


RPC - Principle of Action


CMS RPC

Fast detectors for the first level trigger of the experiment

Considerably good space resolution

Able to work in areas with background ~ 10 3 Hz/cm 2

Price – as low as possible

RequirementsTime resolutionTime resolution ≤ 1.8 ns≤ 1.8 ns

(98 % within 20 ns)(98 % within 20 ns)

EfficiencyEfficiency > 95 %> 95 %

Rate capabilityRate capability ≤ 1kHz/cm2≤ 1kHz/cm2

•Average cluster sizeAverage cluster size < 2 strips < 2 strips •Number of streamersNumber of streamers < 10%< 10%•Operation plateauOperation plateau > 300V> 300V•Power consumptionPower consumption 2-3 W/m2-3 W/m22

•Operational voltage 8.5 –10 kVOperational voltage 8.5 –10 kV


Main Barrel RPC Types

RB4

RB3

RB2

RB1

Length: 2.455 m Width: 1.5, 2.0 , 2.5 mPitch: 40.8, 40.6, 41.0 mm# Strips for Gap: 48, 36, 48, 60

Left Right

Left Right

Out

Out

In

In

Width: 1.48 mPitch: 34.8 mm# Strips for Gap: 42

Width: 1.5, 2.0 , 2.5 mPitch: 27.3, 29.3 mm# Strips for Gap: 84, 90

Width: 1.5, 2.0 , 2.5 mPitch: 22.7, 24.3 mm# Strips for Gap: 84, 90


Barrel RPC Production

GT

HT

Bari

Pavia SofiaChambers production and quality certification involve several steps.

Chambers production and quality certification involve several steps.

ISR

Chamber test Sites

Double gap

GTSingle gap

RB1 in PaviaRB2 & RB4 in BariRB3 in Sofia (& Bari)

Chamber assembling Sites 120 RB1 at HT240 RB2 and RB4 at GT120 RB3 in Sofia (& Bari)


RPC Production Sites

Bari Sofia

Pavia


RPC tests at ISR

ISR RPC storage and test area


Installation of DT and RPC

At SX5

Installation in the CMS Detector

Started in June

At ISR

Coupling RPC to DT

Fast test

Transportation to SX5( CMS surface hall)


Cosmic event in the RPCs


RE1/1

RE1/2

RE1/3

RE2/1

RE2/2

RE2/3

RE3/1

RE3/2

RE3/3

RE4/1

RE4/2

RE4/3

No. of chambers 36*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2

ChinaChina

KoreaKorea

PakistanPakistan

Gap production

Korea

Gap production

Korea

Front-end electronics

Pakistan

Front-end electronics

Pakistan

CERN

Project Co-ordination

ISR Assembly Station

CERN

Project Co-ordination

ISR Assembly Station

Endcap RPC


RPC Production Sites

Korea Pakistan

ISR Lab

Test of first chambers


Muon Trigger


Summary

CMS Muon System – big international project - 3 Continents

DT ChambersDT production ended (266 out of 250)

Delivered to CERN - 262

Installed - 146

CSC ChambersProduction finished (496 out of 468 CSCs)

Delivered to CERN – 495

Installed - 432

RPC Chambers460 (out of 480) barrel RPCs assembled.

End of production - December.

Delivered to CERN – 380

Installed - 278

Endcap RPC – YE+1 and YE+2 installed

Endcap RPC - YE+3 and YE-1 will be installed until the end of the year

Magnet test and Cosmic runs are going now

Documents

The CMS muon system