The ATLAS Detector

(see http://atlas.web.cern.ch/Atlas/Welcome.html)

ATLAS

The Large The Large HadronHadron ColliderCollider at CERN (LHC)at CERN (LHC)

7+7 TeV pp collider25 ns bunch spacing≈ 20 int./crossing

at high luminosity⇒ ≈ 800 million pp collisions per second

Example data sets10 fb-1 (one yr. at

low lumi.)6x1012 b-bbar2x109 W5x108 Z8x106 ttbar2x105 H (mH=150)

Scheduled to begin running in 2007

Particle Detection Principles

The ATLAS Detector

Overall length = 42 m, diameter = 22 m, weight = 7000 tons

Components under construction in over 35 countries around the world

ATLAS Underground Cavern

civil engineering finished April 2003installation of detector components is underway

Webcam picture from May 28/2004

ATLAS Inner Detector

TRT

Pixels SCT

Barrelpatch panels

End-cappatch panels

Services

Beam pipe

r = 1.15 m, length = 7 m ( |η| < 2.5 ), 2 T solenoidal magnetic field

3 layers (r = 4, 11, 14 cm) of 50 µm X 300 µm Si pixels (140E6 in total)4 layers of 80 µm X 12.8 cm Si strips (6.2E6 in total)36 layers of 4 mm dia. X 1.5 m (max) straws (420k in total)

Barrel SCT

ATLAS Inner Detector

Integration of SCT into Barrel TRT

ATLAS Inner Detector Performance

ATLAS Barrel Inner DetectorH→bb

–

b

b–

ATLAS Barrel Inner DetectorH→bb

–

b

b–

Low luminosity Design luminosity

ATLAS Inner Detector Performance (cont’d)

0

50

100

150

200

1 10 102

With B-layerWithout B-layer

|η| < 0.25

pT (GeV)

σ(d 0)

(µm

)

0

100

200

300

1 10 102

With B-layerWithout B-layer

|η| < 0.25

pT (GeV)

σ(z 0)

(µm

)

ATLAS Calorimeters

Calorimeters

Calorimeters

Calorimeters

Calorimeters

Hadronic Tile

EM Accordion

Forward LAr

Hadronic LAr End Cap

The ATLAS Liquid Argon Electromagnetic Calorimeter

47 cm

readout electrode absorber

P

leadglue

kapton

outer copper layer

outer copper layer

inner copper layer

stainless steel

HVHV

liquid

argo

n gap

liquid

argo

n gap

(~2 m

m)

0.7%E

10%E

σ(E)⊕≈

The ATLAS Liquid Argon Calorimeter

0

10

20

30

40

0 1 2 3Pseudorapidity

X0

Barrel-Endcap crack

Presampler

Scintillator

ID services+ patch panel

warm flange

cables + passive liquidMaterialin front of Presampler

Materialin front of Accordion

B A R R E L E N D C A P

Materialin front ofAccordion

Material up to the end of active BarrelMaterial up to the end of active Endcap

Total active depth

The ATLAS LAr Barrel Wheel Assembly

The ATLAS Barrel Cryostat and Superconducting Solenoid

The ATLAS Barrel Cryostat Installation

At Columbia, we have designed and are starting production of the readout electronics for the ATLAS LAr calorimeters

LAr Calorimeter Readout Electronics

read out ≈ 170k channels of calorimeterdynamic range ≈ 16 bitsmeasure signals at bunch crossing frequency of 40 MHz (ie. every 25 ns)store signals during L1 trigger latency of ≈ 2.5 µs (100 bunch crossings)digitize and read out 5 samples/channel at L1 rate of ≈ 100 kHz

measure deposited energies with resolution < 0.25%measure times of energy depositions with resolution << 25 ns

high density (128 channels per board)low power (≈ 0.8 W/channel)high reliability over expected lifetime of > 10 yearsfor on-detector electronics, be tolerant of significant levels of radiation due to intense particle collisions

Requirements of ATLAS LAr Readout

functionality includes:receive input signals from calorimeteramplify and shape themstore signals in analog form while awaiting L1 triggerdigitize signals for triggered eventstransmit output data bit-serially over 1.6 Gbps optical link off detector

Overview of ATLAS Overview of ATLAS LArLAr calorimeter calorimeter frontendfrontend board (FEB)board (FEB)

Overview of main FEB components

32 SCA 16 ADC 8 Gain Select.

1 Glink

1 Config.2 SCAC

1 SPAC

1 MUX

32 Shaper

1 TTCRx

2 CLKFO

20 Regulators 4 LSB

32 0T

128input

Signalsfm calo

1 fiberTo RODs

8 sumsTo TBB

DMILL

DSM

AMS

COTS

FEB Prototype Results

DAC setting-Equivalent Energy Channel(GeV)

RMS = 50MeV RMS = 500MeV

101

102

103

10-1

100

0 20 40 60 80 100 120 140 160 180 200

100

10-1

10-2

2

5

2

5

Electron Energy (GeV)

Tim

ing

Res

olut

ion

(ns)

/E(%

)σ E 2

5

2

5

Time (ns)

Am

plitu

de (

AD

C c

ount

sx10

00)

200 300 400 500

0.0

-0.5

0.5

1.0

1.5

2.0

ATLAS Tile Hadronic Calorimeter

Doublereadout

Hadrons

zr

φ

3%E

30%E

σ(E)⊕≈

ATLAS Calorimetry Depth and Missing ET

0

5

10

15

20

0 1 2 3 4 5Pseudorapidity

Abs

orpt

ion

Len

gth

Tile barrel

Tileextended barrel Hadronic endcap Forward calorimeter

EM barrel EM endcap

Material in front of Muon System

End of activehadronic

cryostat walls

0

5

10

15

0 100 200 300 400 500ΣET in calorimeters (GeV)

σ(p xm

iss ,

p ymis

s ) (

GeV

)

low luminosity new data

ATLAS Toroidal Muon Spectrometer

2

4

6

8

10

12 m

00

Radiation shield

MDT chambers

End-captoroid

Barrel toroid coil

Thin gap chambers

Cathode strip chambers

Resistive plate chambers

14161820 21012 468 m

3 superlayers of tracking chambers (370k drift tubes, 67k CSC) and trigger chambers (355k RPC, 440k TGC)total detector area > 12k m2

toroidal magnetic field provided by array of air-core toroids

ATLAS Muon Detectors

170 t (90 km) superconductor, 700 t cold masstotal stored energy 1.55 GJ

ATLAS Toroidal Magnet System

0

2.5

5

7.5

10

0 1 2η

∫Bdl

(T

m)

φ = π/8

φ = 0

Barrel region End-cap region

Tran

sitio

n re

gion

ATLAS Barrel Toroid Installation

ATLAS Endcap Toroids

ATLAS Muon Momentum Resolution

Energy loss fluctuationsMultiple scattering

Chamber resol and align.

Muon spectrom.standalone

Inner trackerstand alone

The The muonmuon spectrometer resolution spectrometer resolution dominates for Pt > 100 dominates for Pt > 100 GeV/GeV/cc

ATLAS Status Today

Follow progress on Webcams at Follow progress on Webcams at http://atlaseyehttp://atlaseye--webpub.web.cern.ch/atlaseyewebpub.web.cern.ch/atlaseye--webpub/webwebpub/web--sites/pages/UX15_webcams.htmsites/pages/UX15_webcams.htm