ALICE experiment

• Detectors – Photon spectrometer– Central tracking detectors

• ITS, TPC, TRD

– Particle identification

• Data acquisition and trigger

ALICE - general view

In action...• Full simulation of ALICE (shown is a 20 slice)

with Pb-Pb events at max multiplicity

For full event:

ALICE @ Point2: Ready to move in!

ALICE @ Point2: The TPC assembly hall

The ALICE Inner Tracking System

• 6 Layers, three technologies (keep occupancy ~constant ~2%)

– Silicon Pixels (0.2 m2, 9.8 Mchannels)

– Silicon Drift (1.3 m2, 133 kchannels)

– Double-sided Strip Strip (4.9 m2, 2.6 Mchannels)

Rout=43.6 cm

Lout=97.6 cm

SPD

SSD

SDD

Tracking in the ITS:PbPb central event, slice

83o-87o - primary vertex - secondary vertices => for Hyperons => for Charm and Beauty - dE/dx for particle identification (@low momenta)- improve TPC momentum resolution- stand-alone tracking for low-Pt particles

ALICE Silicon Pixel Detector (SPD)

32 columns

Ladder 2: 70.72 mm Ladder 1: 70.72 mm

Half stave ~193 mm

425 m

50

m

Pixel Cell

Frontend chip

Pixel detector

Carrier bus

Power supply ~1m

1 data and 2 control links (~200m)

PCMCM

16.8

mm

15.8

6 m

m

2mm

12

34

56

READOUT CHIP

PIXEL DETECTOR

AluminiumPolyimide

CARBON FIBER SUPPORT

1 ANALOG_GND 25µ2 ANALOG_ POWER 25µ3 HORIZONTAL LINES 10µ4 VERTICAL LINES 5µ5 DIGITAL_POWER 25µ6 DIGITAL_GND 25µ7 RES + CAPA PADS 15µ

12

56

Glue

COOLING TUBE

11mm

600µm

235µm

?

PIXEL_BUS

7 77 7SMD component

=> 150µm +200µm final ?

19/10/01 PR/GS/PG/LHC Pys. & Det., Chia 10

ALICE Pixel Chip • 50 µm x 425 µm pixel cell

• 8192 cells: 32 columns x 256 rows

• Active area: 12.8 x 13.6 mm

• Mixed signal (analogue, digital)

• Commercial 0.25µm CMOS process

• Radiation tolerant design (enclosed gates, guard rings)

• 13 million transistors

• 10 MHz clock

• ~100 µW/channel

• Prototype works to ALICE specs!

• detector final– tender completed, production starts

early ‘02

• 47 detectors pre-production– confirms ~ 70% yield

• Calibration methods compensate for T variations and inhomogeneity of Si

SDD

Drift time (25 ns)

Ano

de n

umbe

r t =0

Pos

itio

ns

of H

V d

ivid

ers

Pos

itio

ns

of H

V d

ivid

ers

Charge injectors event

• FEE final prototype (PASCAL)– design review passed, eng. run 2Q 2002

• event buffer prototype (AMBRA)– design review passed, eng. run 2Q 2002

SDD: frontendP

ream

plif

iers

Analoguememory A

DC

s

SDD electronic chain in beam test• Test of final detectors + electronics with beam @ PS

One MIP

Noise levels

Signal vs. drift distance

• R&D essentially complete• Detector tender completed

– Three companies share the 1800 detector production • New, radtol FEE chip prototype works fine

– very fast development (<one year) by Strasbourg, only minor adjustments needed

– Eng. run first half of 2002

• Hybrid design defined• RO electronics and controls being finalized• NOW: tune production/test/assembly procedures and go into

construction

SSD

SSD assembly• TAB bonding on Al/polyimide flexible microcables • Microcables serve as multilayer hybrids• Known Good Die principle to be applied• Microcables are produced in one of the collaborating institutes

(Kharkov, Ukraine)• Assembly has been proven in labs and in industry => now setting up

the assembly chains (France, Italy, Finland, The Netherlands) to produce the 2000 modules and 72 ladders

• A similar assembly procedure has been developed for the STAR SSD, involving some of the same groups, and applied to ~ 400 detector modules

ISSD front end chip assembly

IISSD Hybrid assembly

IIISSD module assembly

SDD/SSD Supports

• Carbon ladders SSD (St. Petersburg, Russia)

– ~ 80 produced• 100% of strip ladders

• now spares and SDD

– next: assembly of ancillary components

Sag (um) under center load for 11, 130 and 249 gr

020406080

100120140

1 4 7 10 13 16 19 22 25 28 31 34 37 40

Serial number

TPC layout

510 cm

EE

88us

GAS VOLUME88 m3

DRIFT GAS90% Ne - 10%CO2

Readout plane segmentation

18 trapezoidal sectors

each covering 20 degrees in azimuth

TPC readout

TPC status: Field Cage

Cylinders are fabricated from three 120-

degree-‘panels’ glued together (lashing).

Production has started in September 2001

Cylinders are fabricated from three 120-

degree-‘panels’ glued together (lashing).

Production has started in September 2001

Hand lay-up of composite

structureNomex®

Tedlar®

Fiber Pre-Pregs

Aluminum

Honeycomb Core

BEING MANUFACTURED!

TPC status: RO chambers• R&D completed, in production

– Inner RO Chambers 1/4 production done (GSI, Heidelberg, later Bratislava)– Out. RO Chambers start prod. 1st Q02

In assembly

CLOSE-UP ON THE PADS

Pad Plane: 5504 pads (4x7.5 mm2)

CONNECTOR SIDE

TPC status: electronics

• Ion tail cancellation performed digitally

• Commercial ADC integrated on custom digital chip => very substantial saving in power, complexity and $!

• All being prototyped, engineering runs mid 2002

anode wire

pad plane

drift region88s

L1: 5s 200 Hz

PASA ADC DigitalCircuit

RAM

8 CHIPS x

16 CH / CHIP

8 CHIPSx

16 CH / CHIP

CUSTOM IC(CMOS 0.35m) CUSTOM IC (CMOS 0.25m )

DETECTOR FEC (Front End Card) - 128 CHANNELS(CLOSE TO THE READOUT PLANE)

FEC (Front End Card) - 128 CHANNELS(CLOSE TO THE READOUT PLANE)

570132PADS

1 MIP = 4.8 fC

S/N = 30 : 1

DYNAMIC = 30 MIP

CSA SEMI-GAUSS. SHAPER

GAIN = 12 mV / fCFWHM = 190 ns

10 BIT

< 10 MHz

• BASELINE CORR.

• TAIL CANCELL.

• ZERO SUPPR.

MULTI-EVENT

MEMORY

L2: < 100 s 200 Hz

DDL(4096 CH / DDL)

Powerconsumption:

< 40 mW / channel

Powerconsumption:

< 40 mW / channel

gat

ing

gri

d

TPC electronics: ALICE TPCE READOUT CHIP (ALTRO)

0 100 200 300 400 500 600 700-50

0

50

100

150

200filter inputthreshold

0 100 200 300 400 500 600 700-50

0

50

100

150

200Filtered data and fixed threshold

filter outputthreshold

DIGITAL TAIL CANCELLATION PERFORMANCE

AD

C c

ou

nts

AD

C c

ou

nts

Time samples (170 ns)

AdaptiveBaselineCorrect.

I

AdaptiveBaselineCorrect.

I

ADCADC TailCancel.

TailCancel.

DataFormat.

DataFormat.

Multi-EventMemory

AdaptiveBaselineCorrect.

II

AdaptiveBaselineCorrect.

II

+-

10- bit20 MSPS

11- bit CA2arithmetic

18- bit CA2arithmetic

11- bitarithmetic

40-bitformat

40-bitformat

SAMPLING CLOCK 20 MHz READOUT CLOCK 40 MHz

DIGITAL PROCESSOR & CONTROL LOGIC

8 A

DC

s 8 A

DC

s

ME

MO

RY

0.25 m (ST) area:64mm2

power:29 mW / ch SEU protection

Dimuon Spectrometer • Study the production of the J/, ', ,

' and '' versus the centrality of the reaction

• Resolution of 70 MeV on the J/ and 100 MeV on the

• overall performance improved with updated detector design (TDR addendum)

Plot of 1-month Pb run result, showing the good separation of the various resonances, allowing a systematic study of Debye screening

• The spectrometer is taking shape:

– Production of magnet started (yoke and coil)

– Trigger chambers final prototype tested in GIF with final electronics

– Begin of detector production in 2002

The absorber design is being revised to try to overcome a major cost overrun

Transition Radiation Detector (TRD)• main aims:

– high pt (> 1 GeV) electron identification

– trigger on high pt (>3 GeV) electrons and jets

– physics: heavy quarks (c, b), quarkonia (J/Psi, Y), jets

• detector:– fiber radiator to induce TR ( > 2000)

– large (800 m2), high granularity (> 1M ch.) drift detectors

– online trigger electronics to select stiff tracks (measure sagitta)

x6

TRD

ALICE Photon Spectrometer (PHOS)• Physics

– Thermal radiation– High pt physics– Tagged jets

• Detector – Dimensions: 0.12,

100(18 m2) at radius R 4.6 m

– PbWO4 crystals, X0 = 0.89 cm, int = 19.5 cm, Moliere radius: 2.0 cm

– Granularity: 2.22.2 cm2 (, length: 18 cm

0 identified from 3 to > 50 GeV/c– Energy resolution 2% above 3 GeV/c

• Starting pre-production

Forward detectorsPMD

T0R 2.6 < || < 3.3

T0 for the TOF (~ 50 ps time res.) Two arrays of 12 quartz counters. Also backup to V0

FMD Measure Multiplicity and dist. over 1.6 < < 3, -5.4 < < -1.6 Silicon pad detector disks (slow readout) with 12k analog channels (occ.>1)

V0 1.6 < |< 3.9 Interaction trigger, centrality trigger and beam-gas rejection. Two arrays of 72 scintillator tiles readout via fibers

T0L

ZN

ZP

Proton

ZDC (ZP) Neutron

ZDC (ZN) EM

ZDC

Dimensions (cm3)

12x21x150 7x7x100 7x7x21

Absorber brass W-alloy lead

Fibre angle wrt LHC axis

0O 0O 45O

Fibre (m) 550 365 550

Aim: determination of the impact parameter of the collision by measuring the energy carried by the spectator nucleons

Where: hadronic calorimeters at ~ 116 m from IP e.m. calorimeter at ~ 8 m from IP

Central events selected with both: -Energy in hadronic calorimeters < E0

-Energy in e.m. calorimeter >E1

E0

E1

Ehad vs Ee.m.

ALICE ZDC Calorimeters

PCI

MEMCPU

RORC

LDC/L3CPU

NIC

L2 Trigger

PDS

36 TPC Sectors

FEE

DDL

L1 Trigger

Switch

TriggerData

Trigger Decisions

Detector busy

FEEFEE

PDS PDS PDS

L0 Trigger

FEE

FEE

FEE

Trigger Detectors: Micro Channelplate- Zero-Degree Cal.- Muon Trigger Chambers

- Transition Radiation Detector

RORCRORC

PCI

MEMCPU

RORC

LDC/FEDC

NIC

RORCRORC

PCI

MEMCPU

RORC

LDC/FEDC

NIC

RORCRORC

PCI

MEMCPU

RORC

LDC/FEDC

NIC

PCI

MEMCPU

RORC

LDC/L3CPU

NIC

FEE

PCI

MEMCPU

RORC

LDC/L3CPU

NICPCI

MEMCPU

RORC

LDC/L3CPU

NICPCI

MEMCPU

RORC

LDC/L3CPU

NIC

FEE

PCI

MEMCPU

RORC

LDC/L3CPU

NICPCI

MEMCPU

RORC

LDC/L3CPU

NICPCI

MEMCPU

RORC

LDC/L3CPU

NIC

RORCRORC

PCI

MEMCPU

RORC

LDC/FEDC

NIC

LDC: Local Data Concentrator; Software running on standard CPUFEDC: Front-End Digital Computer - generic commercial off-the-shelf CPURORC: ReadOut Receiver Card (PCI based)L3CPU: L3 Processor - generic commercial off-the-shelf CPUGDC: Global Data Concentrator - generic commercial off-the-shelf CPUNIC: Network Interface Card

PCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NIC

PCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NIC

L3/DAQ/Processor Farm Switch FabricEDM

PCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NIC

PCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NIC

PCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NIC

PCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NICPCIMEMCPU

GDC/L3CPU

NIC

Computer centre

InnerTrackingSystem

MuonTrackingChambers

ParticleIdentification

PhotonSpectrometer

DAQ and Trigger

TPC event

(only about 1% is shown)

Data volume and event rate

TPC detector

data volume = 300 Mbyte/event, data rate = 200 Hz

front-end electronics

DAQ – event building

realtime data compression & pattern recognition

PC farm = 1000 clustered SMP

permanent storage system

bandwidth

60 Gbyte/sec

15 Gbyte/sec

< 1.2 Gbyte/sec

< 2 Gbyte/sec

parallel processing

HLT trigger

• Trigger rates ptsingle > 1 GeV/c ptsingle > 0.8 GeV/c

ptpair > 3 GeV/cJ//event 0.007 0.0006

background/event 0.39 0.15

TRD @ 1kHzTPC @ 150 Hz

Online track reconstruction:1) selection of

e+e—pairs (ROI)

2) analysis of e+e—pairs

(event rejection)

HLT system

HLT trigger

TRDTrigger~2 kHz

GlobalTrigger

Zero suppressed TPC Data

Sector parallel

Other Trigger Detectors,L0pretrig.

L1

L2 accept(180 Links, 83 MB/evt)

L0

ReadoutTPC

Readoutother detectors

L1

Tracking ofe+e- candidates

inside TPC

Selectregions of

interest

Verify e+e-

hypothesis

TRDe+e- tracks

Rejectevent

Track segmentsAnd space points

e+e- tracksPlus ROIs

On-line Data reduction(tracking, reconstruction,

partial readout,compression)

seed

s

enable

L0

L1

L2

HLT

DAQ

Tim

e, c

ausa

lity

0.5-2 MB/evt) 4-40 MB/evt)

Detector raw data readout for debugging

Binary loss less Data compression (RLE, Huffman, LZW, etc.)

45 MB/evt)

Event sizes and number of links TPC only

Event sizes and number of links TPC only