The CMS Construction - Infn

infn.it

The CMS Construction - Infn

The CMS Construction


(CMS) Design Criteria

Very good muon identification and momentum

measurement

Trigger efficiently and measure sign of TeV muons dp/p < 10%

High energy resolution electromagnetic calorimetry

~ 0.5% @ E T ~ 50 GeV

Powerful inner tracking systems

Momentum resolution a factor 10 better than at LEP

Hermetic calorimetry

Good missing E T resolution

(Affordable detector)

Transparency from

the early 90’s


High Interaction Rate

Experimental Challenge

LHC Detectors (especially ATLAS, CMS) are radically

different from the ones from the previous generations

pp interaction rate 1 billion interactions/s

Data can be recorded for only ~10 2 out of 40 million crossings/sec

Level-1 trigger decision takes ~2-3 μs

electronics need to store data locally (pipelining)

Large Particle Multiplicity

~ superposed events in each crossing

~ 1000 tracks stream into the detector every 25 ns

need highly granular detectors with good time resolution for low occupancy

large number of channels (~ 100 M ch)

High Radiation Levels

radiation hard (tolerant) detectors and electronics


The CMS Detector


The CMS Collaboration (2007)

Member States

Non-Member States

USA

Total

Member States

Non-Member States

USA

Total

Number of

Laboratories

59

67

49

175

# Scientific

Authors

1084

503

723

2310

Associated Institutes

Number of Scientists

Number of Laboratories

Oct. 3rd 2007/gm

62

9

Uzbekistan

Russia

USA

Austria

Belgium

CERN

France

Bulgaria

Italy

Finland

Ukraine

Georgia

Belarus

UK

Poland

Armenia

Portugal

Turkey

Brazil

Serbia

China, PR Spain

Pakistan

China (Taiwan)

Lithuania

Switzerland

Mexico

Korea

Iran Colombia

New-Zealand

Croatia

Ireland India Cyprus

Estonia

2310 Scientific Authors

38 Countries

175 Institutions

Germany

Greece

Hungary


Exploded View of CMS

Plus Side

Minus Side


Assembly of Iron Yoke

2003


Assembly of the Coil


Assembly of the Coil

Sept 05

Coil: 230 tons

Outer vacuum tank:

13 m long SS tube, φ=7.6 m


Surface Hall: Barrel Muons


Lowering of Heavy Elements

YE+1 (Jan’07)


Lowering of Heavy Elements

Feb 2007


Insertion of Barrel ECAL

Jul’07


Completion of Services on YB0

Nov. ‘07


Dic. ‘07

Lowering of Tracker


Dic. ‘07

Tracker Insertion


Dic. ‘07

Tracker in CMS


Extreme engineering: 4T, big dimensions & large magnetic deformation

E/M (kJ/kg)

12.0

10.0

8.0

6.0

4.0

2.0

0.0

ZEUS

TOPAZ

SDC-model

ATLAS -sol.

ALEPH

CDF

H1

CLEO2

DELPHI

VENUS

The CMS SC Solenoid

Design Goal: Measure 1 TeV/c muons with < 10% resolution

5 modules Φ 6900 mm ; L 2500 mm ; W= 50 t

ATLAS End-caps

10 100 1000 10000

Stored Energy (MJ)

CMS

ATLAS Barrel

Solenoid composed by

5 modules

(CB-2, CB-1, CB0,

CB+1, CB+2)

I = 20kA


Winding of the Coil

Specific winding technology developed by INFN Genova

in collaboration with Ansaldo Superconduttori

Winding


24 July

Test of the Magnet (2006)

Magnet Current Cycles achieved

during August

28 August

19 kA, 4 Tesla!

2 days

stable

operation

at 3.8 T


Tracking at LHC

Need factor 10 better momentum resolution than at LEP

1000 particles emerging every crossing (25ns)

Fluence over

10 years of

LHC

Operation


Layout of CMS Tracking

120 cm

CMS

TOB

TEC

TIB

TID

Pix

300 cm

Si pixels surrounded by silicon strip detectors

Pixels: ~ 1 m 2 of silicon sensors, 65 M pixels, 100x150 μm 2 , r = 4, 7, 11 cm

Si μstrips : 223 m 2 of silicon sensors, 10 M strips, 10 pts, r = 20 – 120 cm


The CMS Tracker

• Pixel

• Silicon Strip Tracker

Largest Silicon Strip Detector

ever built:

~200m 2 of silicon,

instrumented volume ~24m 3

TIB (4 layers )

TID (3 disks, 3 rings )

TOB (6 layers)

TEC (9 disks, 7 rings )


Si Modules and Electronics Chain

Si Sensors

Ride on

technology wave

75k chips using

0.25μm technology

Detector

TTCrx

CLK

CCU

Tx/Rx

Tx/Rx

T1

I2C

Control

module

digital

optical

link

μP

PLL

Front End Controller

APV

Optical

transmitter





analogue

optical

link








ADC


FPGA

Front End Module

TTCrx

DCU

256:1

APV

MUX

FPGA

RAM

Front End Driver


System Components

• Module


Sensor + FE Hybrid

• chip: APV25 (128 strips) - analog

• Optical converter (AOH)


one laser/fiber = 256 strips

• Controls/Clock/Trigger



Control chip (CCU)

• I2C protocol with modules

• rings of CCUs

Digital optical converted (DOH)

• optical link to VME controller (FEC)

Hybrid+AOH

Controls

String


System Components

Modules (all)

AOH (Perugia)

DOM (Firenze)

CCUM (Cern)

Mother cable (Bari)


The Start of the TIB Integration

Apr. ‘05

The first string


Si Tracker

TIB

TEC


Si Tracker


Si Tracker


Tracker Readied for Installation

Dead channels ~ 0.5 ‰ stable in time

Noisy channels ~ 0.5 % stable in time


Lead Tungstate ECAL

Design Goal: Measure the energies of photons from a decay of

the Higgs boson to precision of ≤ 0.5%

CMS chose scintillating crystals

To CMS

m 3

10

CMS

75000 PWO

Cleo II

7800 CsI(Tl)

Belle

8816 CsI(Tl)

From Crystal Ball

5

Babar

6580 CsI(Tl)

Crystal Ball

672 NaI(Tl)

L3

12000 BGO

Crystal Barrel

1380 CsI(Tl)

TAPS

600 BaF2

KTeV

3100 CsI

Alice

17920 PWO

P. Lecoq

1972

1985

1986

1989

1990

1999

2008


CMS Requests and PWO

To comply with LHC and CMS

conditions ECAL must be:

• fast

• compact

• highly segmented

• radiation resistant

1995 1998

2

T dependent: -2%/°C

Very low light output

Very effective in high

energy γ containment


ECAL layout

PWO: PbWO 4

about 10 m 3 , 90 t

barrel cystals

Pb/Si

preshower

Barrel: |η| < 1.48

Barrel: | < 1.48

36 Super Modules

61200 crystals (2x2x23cm(

2x2x23cm 3 )

barrel

Super Module

(1700 crystals)

endcap

supercystals

(5x5 crystals)

EndCap “Dee”

3662 crystals

EndCaps: 1.48 < |η| | | < 3.0

4 Dees

14648 crystals (3x3x22cm

(3x3x22cm 3 )


Choice of the Photodetector

20

d eff ~6μm

40μm

Avalanche photodiodes (APD)

Two 5x5 mm 2 APDs/crystal

- Gain: 50 QE: ~75% @ λ peak = 420 nm

- Temperature dependence: -2.4%/ O C

- Gain dependence on bias V: 3%/V


PWO Production

BARREL ingot

EE INGOT

ENDCAPS ingots

Delivered Barrel crystals

63000

61000

59000

57000

55000

53000

51000

49000

47000

45000

BARREL CRYSTALS ~ 1150 xl/m

Dec-05 Mar-06 Jul-06 Oct-06 Jan-07 Apr-07


EB Construction: Regional Centers

Submodule

2x5 crystals

Module

400 crystals

CERN Lab.27

EP-CMA

&

Casaccia

Assembly and test of modules in RC: ENDED in March 2007


INFN/ENEA Regional Center

Check crystals in Rome RC

Glue subunits and check APD gain

The first submodule!

Y 2002

The first module!


EB Construction: Super Modules

Cooling and electronics integration: completion by May 2007

Supermodule

1700 crytsals

Dead channels: 19/61200


Response to high energy electrons

ECAL Performance

0.5%

Temperature Stability: ≤ 0.1 °C

Light response stability: ≤ 0.1%


ECAL: Cosmics Signal in CMS


Layout of CMS Muon System

250 DTs 468 CSCs 480 RPCs


Muon System: Drift Tubes

42mm

Wire

Mylar

Electrode

Strip

13 mm

Spatial resolution:

Single cell ∼ 200 μm

Chamber ∼ 100 μm


DT Chambers Assembly

Legnaro Assembly Hall

Assembly of 250 DT chambers:

70 Aachen, 70 Madrid

70 Padova, 40 Torino

•1 layer= 70 wires

• 27 gluing operations/chamber

• 1 gluing operation = 1 day

Precision of 100 μm over 5-10 m 2

Torino Assembly Hall


Muon System: Start of Installation

First installation Aug.03

CERN ISR

Salvato

First installation test Aug. 2002

Peghin


Muon System Completed

ISTALLATION OF THE LAST

OF THE 250 DT CHAMBERS

IN THE CAVERN. IN WHEEL

YB0

26 Oct. 2007


Muon System: YB0 DTs in Operation!

30Hz

S03

15Hz

S01

3Hz

S12

10Hz

17Hz

S11


Muon System: Resistive Plate Chambers

Gas mixture

95.5 C2H2F4

95.5 C

3.5 iC4H10

0.3 SF6

+ RH 50%

Main Unit of a RPC:

Single Gap (SG)

Two SG coupled with

readout plane in between

Main characteristics of the RPCs

used in CMS:

•Bakelite thickness: 2 mm

•Bakelite bulk resistivity :

2-6 10 10 Ωcm

• Gas Gap width: 2 mm

•Operating voltage: 9.2-9.8 kV


RPC chamber layout

480 RPCs coupled with DTs and inserted

into the iron return yoke of the magnet

RB4 120 chambers (2 double gaps/chamber)

RB3 120 chambers (2 double gaps/chamber)

RB2 60 chambers (2 double gaps/chamber) +

60 chambers (3 double gaps/chamber)

RB1 120 chambers (2 double gaps/chamber)

Forward UP

Backward UP

Double

Gap DG

Double

Gap DG

Forward Down

Backward Down


RPC Performance

Cluster size

Efficiency

Counting rate

All parameters are

compatible with the

results obtained during

the production tests


RPC: First Events in CMS


First Closure of the CMS Experiment

(2006)


Magnet Test & Cosmic Challenge

(MTCC)

ECAL

Magnet

HCAL

Tracker

Muon chambers


Run 2605 / Event 3981 / B 3.8 T / 27.08.06


Cosmics in the Tracker (Bat 186)

A cosmic at -15°C

Validated clusters shown

Example of Performance

Normal Strips 99.852 %

(241 313 Strips)

Dead Strips 0.116 %

(275 Strips)

Noisy Strips 0.032 %

(76 Strips)

The Quality of the CMS Tracker is Excellent:

• Dead or Noisy Strips < 3 / 1000

• Signal: Noise > 25:1 in Peak Readout Mode

• Enormous experience gained in operating the Tracker at TIF


Performance of CMS: Overview

Tracking

HCAL

b-tagging

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