Post on 11-Jan-2016
Riken, Nov. 2002 ALICE at LHC J. Schukraft 1
Heavy Ions @ LHC Heavy Ions @ LHC Heavy Ions @ LHC Heavy Ions @ LHC
Heavy Ion Physics Heavy Ion Physics at LHCat LHC
LHC machineLHC machine
ALICEALICECollaborationDetectorPerformance
RIKEN 10/2002 J. Schukraft2
Physics@LHC: Physics@LHC: CaveatCaveat
long distance QCD is difficult to predictlong distance QCD is difficult to predict Theory well known, not so its consequences or manifestation HEP@LHC: Theory unknown, but each candidate makes precise predictions
the fate of 'expectations' at SPS and RHICthe fate of 'expectations' at SPS and RHIC some expectations turned out right: SPS: strangeness enhancement RHIC: particle ratios, jet-quenching(?)
some turned out wrong: SPS: large E-by-E fluctuations RHIC: multiplicity dN/dy
a number of unexpected surprises: SPS: J/Psi suppression RHIC: elliptic flow, 'HBT-puzzle'
lesson when preparing ALICE at LHClesson when preparing ALICE at LHC guided by theory and expectations, but stay open minded !
'conventional wisdom''conventional wisdom' soft physics: smooth extrapolation of SPS/RHIC necessary, but boring ???
hard physics: new domain at LHC
Predictions are notoriously difficult, Predictions are notoriously difficult, in particular if they concern the future..in particular if they concern the future..
BIG Step ahead: BIG Step ahead: SPSSPS RHICRHIC LHCLHC x 28x 28 x 12x 12
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Hard Probes @ Hard Probes @ LHCLHC
LHC: the full 'spectrum' LHC: the full 'spectrum' soft -> semihard -> hard (>> 20 GeV) difficult to overcome power law with Luminosity !
high pt important in order to leave even tails of 'hydrodynamics'
factor 10 every 2-3 GeVfactor 10 every 2-3 GeV
X 2000X 2000
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Jets in ALICE |Jets in ALICE ||<0.9|<0.9
Reasonable rate up to ET ~300 GeV
2.8 102.8 1044
1.2 101.2 1055
8.1 108.1 1055
1.5 101.5 1077
4.9 104.9 101010
accepted accepted jets/monthjets/month
1.1 101.1 10-4-4200200
4.8 104.8 10-4-4150150
3.5 103.5 10-3-3100100
7.7 107.7 10-2-25050
3.5 103.5 102255
jets/eventjets/eventppt t jet >jet >
(GeV/c)(GeV/c)
First TRD studies ~ 1Hz trigger rate for central PbPb collisions and pt jet > 100 GeV/c
real jets triggers 0.7/sfalse triggers 0.3/s
Pb Pb rates:
ppL = 1030cm-2s-
1
ideal energy for jet-quenching:ideal energy for jet-quenching: around 100 GeVaround 100 GeV pQCD applicable jets measurable above soft background energy loss still relatively large effect E/E ~ O(10%), decreasing with E !
RIKEN 10/2002 J. Schukraft5
Heavy Quarks & QuarkoniaHeavy Quarks & Quarkonia copious heavy quark productioncopious heavy quark production charm @ LHC ~ strange @ SPS hard production => 'tracer' of QGP dynamics (statistical hardonization ?) 2 mc ~ saturation scale => change in production ? jet-quenching with heavy quarks visible in inclusive spectra ?
Y dY d/dy LHC ~ 20 x RHIC/dy LHC ~ 20 x RHIC Y will probably need higher Lumi at RHIC even at LHC Y'' is difficult
Y productionY production
RHICRHIC LHCLHC
R. Vogt, hep-ph/0205330
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few hundred per month(from K.Kajantie, K.Eskola)
dNch/d ~ 2500
What multiplicity do we expect?What multiplicity do we expect? old estimates: dN old estimates: dNchch/dy 2000 - 8000, /dy 2000 - 8000, can we extrapolate from RHIC data ?can we extrapolate from RHIC data ?
RIKEN 10/2002 J. Schukraft7
Initial Initial ConditionsConditions
<0.2<0.2~0.5~0.5~1~10 0 (fm/c)(fm/c)
4-104-101.5-4.01.5-4.0<1<1QGP QGP (fm/c)(fm/c)
2x102x1044(?)(?)7x107x1033101033VVff(fm(fm33))
15-4015-403.5-7.53.5-7.52.52.5 (GeV/fm(GeV/fm33))0=1fm0=1fm
22-8 x10-8 x1033700700-1500-1500430430dNdNchch/dy/dy
550055002002001717ss1/21/2(GeV) (GeV)
LHCLHCRHICRHICSPSSPSCentral collisionsCentral collisions
my pre-RHIC guess (QM2001)my pre-RHIC guess (QM2001) still expect conditions to be significantly different only LHC will give the final answer !
Significant gain in Significant gain in , V, , V, x 10x 10 SPS -> LHC SPS -> LHC
x 3-5x 3-5 RHIC -> LHC RHIC -> LHC
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The Soft StuffThe Soft Stuff
Freeze-out Hyper surfaceFreeze-out Hyper surface
SPSSPS
LHCLHC
changes in expansion dynamics & freeze-out ARE expectedchanges in expansion dynamics & freeze-out ARE expected will the measured transverse HBT volume (finally) increase ? thermal freeze-out temperature ? how will charm fit into particle ratios ? will anisotropic flow change shape of freeze-out volume ? Event-by-Event fluctuations ? measurement accuracy increases ~ #particles
AGSAGS RHICRHIC LHC ?LHC ?
Biggest surprise Biggest surprise would be none..would be none..
RIKEN 10/2002 J. Schukraft9
LHC LHC StatusStatus
the long & winding road to LHCthe long & winding road to LHC first discussion on HI in LHC: 1990 LHC approved 1994 /1996 start-up several times postponed
CERN financial problemsCERN financial problems some 20% cost overrun (~800 MCHF) solution in sight reduce non- LHC program, bank loans, savings, 1 year delay
machine well into constructionmachine well into construction civil engineering almost finished ~ 20 production magnets tested
LHC start-up: LHC start-up: April 2007April 2007
first short heavy ion run: end 2007
External Machine External Machine Review Committee: Review Committee:
'Tight, but feasible''Tight, but feasible'
Atlas cavernAtlas cavern
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LHC LHC MagnetsMagnets
Main DipoleMain Dipole Transfer LinesTransfer Lines
MQWMQWInsertion (Japan)Insertion (Japan)
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Heavy Ions in LHCHeavy Ions in LHC energyenergy Ebeam = 7 x Z/A [TeV]s = 5.5 TeV/A (Pb-Pb), 14 TeV (pp)
beamsbeams possible combinations: pp, pA, AA constant magnetic rigidity/beam ('single magnet')
expected heavy ion running ~ 6 weeks heavy ion runs, typically after pp running (like at SPS) initial emphasis on Pb-Pb pp and pA comparison runs intermediate mass ion (eg Ar-Ar) to vary energy density
later options: different ion species, lower energy AA and pp
luminosity luminosity low L runs: avoid pile-up in TPC
high L runs: max rate in muon arm
RIKEN 10/2002 J. Schukraft12
ALICE Set-upALICE Set-up
HMPID
Muon Arm
TRD
PHOS
PMD
ITS
TOF
TPC
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-6-4-3-2-101234 90o 180o 270o 360o
Rap id ity
Azimuth
FMD -5.4 < <-1.6-2.3<<-3.5
1.6<<32.4<<4
+++:-0.9<<0.9-2<<2
-.45<<0.45φ=57ο-.12<<0.12φ=100ο
-6
-4
-3
-2
-1
0
1
2
3
4
90o 180o 270o 360o
Rapidity
Azimuth
FMD -5.4 < <-1.6
PMD-2.3<<-3.5
FMD1.6<<3
Muonarm2.4<<4
ITS+TPC+TRD+TOF:-0.9<<0.9
ITSmultiplicity-2<<2
HMPID-.45<<0.45
φ=57ο
PHOS-.12<<0.12φ=100ο
ALICE ALICE AcceptanceAcceptance
central barrelcentral barrel -0.9 < -0.9 < < 0.9 < 0.9 tracking, PID single arm RICH (HMPID) single arm em. calo (PHOS)
forward muon armforward muon arm 2.4 < 2.4 < < 4 < 4 absorber, dipole magnettracking & trigger chambers
multiplicitymultiplicity -5.4 < -5.4 < < 3 < 3 including photon counting in PMD
trigger & timingtrigger & timing dets dets Zero Degree Calorimeters T0: ring of quartz window PMT's V0: ring of scint. Paddles
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ALICE CollaborationALICE Collaboration
UKPORTUGAL
JINR
GERMANY
SWEDENCZECH REP.
HUNGARYNORWAY
SLOVAKIA
POLANDNETHERLANDS
GREECE
DENMARKFINLAND
SWITZERLAND
RUSSIA CERN
FRANCE
MEXICOCROATIA ROMANIA
CHINA
USAARMENIA
UKRAINE
INDIA
ITALYS. KOREA
937 Members
(63% from CERN MS)
28 Countries
77 Institutes
0
200
400
600
800
1000
1200
1990 1992 1994 1996 1998 2000 2002 2004
ALICE Collaboration statistics
LoI
MoU
TP
TRD
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ALICE Technical BoardALICE Technical Board
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ALICE Design PhilosophyALICE Design Philosophy General Purpose Heavy Ion DetectorGeneral Purpose Heavy Ion Detector one single dedicated HI expt at LHC ATLAS/CMS have some interest, but priority is pp physics AGS/SPS: several (6-8) 'special purpose expts' RHIC: 2 large multipurpose + 2 small special purpose expts
cover essentially all known observables of interestcover essentially all known observables of interest comprehensive study of hadrons at midrapidity large acceptance, excellent tracking and PID
state-of-the-art measurement of direct photons excellent resolution & granularity em calo (small but expensive !)
dedicated & complementary systems for di-electrons and di-muons cover the complete spectrum: from soft (10's of MeV) to hard (100's of GeV) more recent design feature, still incomplete ...
stay open for changes & surprisesstay open for changes & surprises high throughput DAQ system + powerful online intelligence ('PC farm') flexible & scalable: minimum design prejudice on what will be most interesting
RIKEN 10/2002 J. Schukraft17
Reality is more difficult..Reality is more difficult.. technical and financial constraints lead to compromisestechnical and financial constraints lead to compromises acceptance is limited to about y = 2 fragmentation region is not addressed in any case, difficult at LHC (beam rapidity = 9)
robust tracking <-> rate capability limited by pile-up in TPC to some 8 kHz in AA
no large area calorimeters at least, not yet…
RIKEN 10/2002 J. Schukraft18
L3 magnetL3 magnet still largest magnetstill largest magnet magnet volume: 12 m long, 12 m high 0.5 T solenoidal field
Adding door plugsRemoving L3
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The ALICEThe ALICE Magnet: Magnet:
ready for the experiment to move in!ready for the experiment to move in!
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ALICE ALICE R&DR&D
Inner Tracking System (ITS)Inner Tracking System (ITS) Silicon Pixels (RD19) Silicon Drift (INFN/SDI) Silicon Strips (double sided) low mass, high density interconnects low mass support/cooling
TPC TPC gas mixtures (RD32) new r/o plane structures advanced digital electronics low mass field cage
em calorimeterem calorimeter new scint. crystals (RD18)
PIDPID Pestov Spark counters Parallel Plate Chambers Multigap RPC's (LAA) low cost PM's solid photocathode RICH (RD26)
DAQ & ComputingDAQ & Computing scalable architectures with COTS high perf. storage media GRID computing
miscmisc micro-channel plates rad hard quartz fiber calo. VLSI electronics
1990-1996:Strong, well organized, well funded R&D activity
• R&D made effective use of long (frustrating) wait for LHC• was vital for all LHC experiments to meet LHC challenge !
??
?
RIKEN 10/2002 J. Schukraft21
Time of Flight DetectorsTime of Flight Detectors aim: state-of-the-art TOF at ~1/10 current price ! aim: state-of-the-art TOF at ~1/10 current price ! requirements: area > 150 m2, channels ~ 150,000, resolution < 100 ps existing solution: scintillator + PM, cost > 120 MSF ! R&D on cheaper fast PM's in Russia failed to deliver
gas TOF counters + VLSI FEEgas TOF counters + VLSI FEE Pestov Spark Counter (PSC)
100 m gap, > 5 kV HV, 12 bar, sophisticated gas < 50 ps, some 'tails' (?), but only (!) ~ 1/5 cost technology & materials VERY challenging
Parallel Plate Chamber (PPC) 1.2 mm gap, 1 bar, simple gas & materials 1/10 cost, but only = 250 ps unstable operation, small signal
Multigap Resistive Plate Chambers (MRPC) breakthrough end 1998 after > 5 years of R&D ! many small gaps (10x250 m), 1 bar, simple gas & materials ~ 1/10 cost, < 100 ps , simple construction & operation,..
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The RHIC connection..The RHIC connection.. already used at RHICalready used at RHIC HMPID 2 years sabbatical at STAR double sided SSD being installed @ STAR PMD ALICE copy @ STAR ROOT (offline) all 4 expts
concrete upgrade plansconcrete upgrade plans TOF MRPC finally, a 2 TOF for STAR... TPC FEE replace existing FEE in STAR silicon pixels SPD PHENIX, fallback for STAR
of potential interest ..of potential interest .. high resolution PbW04 calo PHENIX ? TRD test module PHOBOS ??? high bandwidth DAQ ?? distributed GRID computing ??
RIKEN 10/2002 J. Schukraft23
Inner Tracking System (ITS)Inner Tracking System (ITS)
6 Layers, three technologies 6 Layers, three technologies (keep occupancy ~constant (keep occupancy ~constant ~2% ~2% for max mult)for max mult)
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
Major technological challenge!Material Budget: < 1% X0 per layer !
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ITS Electronics DevelopmentsITS Electronics Developments(all full-custom designs in rad. tol., 0.25 (all full-custom designs in rad. tol., 0.25 m process)m process)
Pre
ampl
ifie
rs
Analoguememory
AD
Cs
ALICE PIXEL CHIP50 µm x 425 µm pixels 8192 cells Area: 12.8 x 13.6 mm2
13 million transistors ~100 µW/channel
ALICE SDD FEEPascal chip:64 channel preamp+ 256-deep analogue memory+ ADC Ambra chip:64 channel derandomizer chip
ALICE SSD FEEHAL25 chip:128 channelsPreamp+s/h+ serial out
And extreme lightweight interconnection techniques:
SSD tab-bondable Al hybrids
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System testing and setting up of series System testing and setting up of series productionproduction
Pixel ladder Strip moduleassembly
Drift cooling system
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ITS Support Acceptance TestITS Support Acceptance Test
Deformation < 200 m under load of 1 kg
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25 µm aluminized Mylar on Al frameCentral Electrode PrototypeCentral Electrode Prototype
~ 3 m diameter
drift gas90% Ne - 10%CO2
Field Cage Inner Vessel
TPTPCC
largest everlargest ever 88 m3, 570 k channels
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TPC Field TPC Field CageCage
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TPC R/O chambersTPC R/O chambers
~ 1/2 of inner R/O chambers ~ 1/2 of inner R/O chambers readyready
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TPC: TPC: ElectronicsElectronics
STAR/NA49: STAR/NA49: precise tail cancellation, analogue storage, digital processing off det. precise tail cancellation, analogue storage, digital processing off det. ALICE: ALICE: simple shaping, fast ADC, digital shaping & filtering on detectorsimple shaping, fast ADC, digital shaping & filtering on detector
ALTRO: ALTRO: commercial ADC integrated with custom digital chip: commercial ADC integrated with custom digital chip: SoCSoC 0.25 micron technology (ST), 64 mm2, 29 mW/ch, SEU protection System-on-Chip challenge: integrate analogue & digital functions w/o degradation of performance !
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
RIKEN 10/2002 J. Schukraft31
ZERO SUPPRESSION THRESHOLD: 5 ADC COUNTS
TPC Electronics:TPC Electronics: ALALICE ICE TTPCE PCE RREADEADOOUT CHIPUT CHIP (ALTRO)(ALTRO)
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
ALTRO OUTPUTFILTER DISABLED
ALTRO OUTPUTFILTER ENABLED
THE TEST INPUT SIGNAL IS A CONVOLUTION OF
THE SIGNAL MEASURED ON THE TPC PROTOTYPE
WITH THE AMPLITUTE AND ARRIVAL TIME
DISTRIBUTIONS GENERATED BY ALIROOT
ALTROtest result
RIKEN 10/2002 J. Schukraft32
ALTRO: Better-Smaller-ALTRO: Better-Smaller-CheaperCheaper
4cards16 ch
13
5 m
m
1998channels per chip: 1
ADC: 1 externalDigital Filter: no
1999channels per chip: 4
ADC: 4 externalDigital Filter: no
2001channels per chip: 16
ADC: 16 internalDigital Filter: yes
Integrated ADCs
20
mm
4 PQFP 100
8 SSOP 28
24 mm
Under discussion for STAR TPC !
DIGITAL PROCESSOR & CONTROL LOGIC
8 A
DC
s 8 A
DC
s
ME
MO
RY
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Tracking ChallengeTracking Challenge
STARSTAR
NA49 ALICE 'worst case' scenario:
dN/dych = 8000
RIKEN 10/2002 J. Schukraft34
TrackinTrackingg robust, redundant tracking from 60 MeV to 100 GeVrobust, redundant tracking from 60 MeV to 100 GeV
modest soleniodal field (0.5 T) => easy pattern recognition long lever arm => good momentum resolution silicon vertex detector (ITS) 4 cm < r < 44 cm stand-alone tracking at low pt
Time Projection Chamber (TPC) 90 cm < r < 250 cm Transition Radiation Detector (TRD) 290 cm < 370 cm
p/p (%) for B=0.4T TPC+ITS
TPC+ITS+TRDTracking efficiency in TPC vs. multiplicty
p/p ~ 16% at 100 GeV
(~ 11% at dN/d = 2000)
RIKEN 10/2002 J. Schukraft35
Vertex FindingVertex Finding little material + good resolution + close to vertexlittle material + good resolution + close to vertex primary vertex: 15 m (r) x 5 m (z)
secondary vertices: heavy quarks (100's m) hyperons (cm)
ITS Primary vertex
d0 < cut resonancesd0 > cut D,B mesons
impact parameter d0 (r)
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stable hadrons (stable hadrons (, K, p): 100 MeV < p < 5 GeV, K, p): 100 MeV < p < 5 GeV dE/dx in silicon (ITS) and gas (TPC) + Time-of-Flight (TOF) + Cerenkov (RICH) dE/dx relativistic rise under study => extend PID to several 10 GeV ??
decay topology (Kdecay topology (K00, K, K++, K, K--, , )) still under study, but expect K and decays up to at least 10 GeV
leptons (e, leptons (e, ), photons, ), photons, 00
electrons in TRD: p > 1 GeV muons: p > 5 GeV 0 in PHOS: 1 < p < 80 GeV
Particle IdentificationParticle Identification
0 1 2 3 4 5 p (GeV/c)
1 10 100 p (GeV/c)
TRD e / PHOS /0
TPC + ITS (dE/dx)
/K
/K
/K
K/p
K/p
K/p
e /
e /
HMPID (RICH)
TOF
Alice uses ~ all known techniques!
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DOUBLE STACK OF 0.5 mm GLASS
Edge of active area
cathode pick up pad
cathode pick up pad
anode pick up pad
Resistive layer (cathode)
Resistive layer (cathode)
Resistive layer (anode)
Resistive layer (anode)
5 gaps
5 gaps
160 m2, 160 k channelsr = 3.7 m, < 100 ps
for , K, p PID , K for p <2 GeV/cp for p <4 GeV/c
full size TOF modules under test
Multigap Resistive Plate Chambers
Time Of FlightTime Of Flight
96 readout pads per
strip
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TOF Test ResultsTOF Test Results
0 500 1000-500-1000
1200
1000
800
600
400
200
0
STRIP 10 H.V. +- 6 kV
Time with respect to timing scintillators [ps]
= 53 ps minus 30 ps jitter
of timing scintillator = 44 ps
Entries/50 ps
404550556065707580
5.0 5.5 6.0 6.5
0
20
40
60
80
100
5.0 5.5 6.0 6.5
Efficiency [%]
Applied voltage [kV]Resolution [ps]
strip 12strip 10
Applied voltage [kV]
strip 12strip 10
Typical performance
Typical time spectrum
other expts using ALICE MRPC technologyother expts using ALICE MRPC technology HARP @ CERN (expt. finished) STAR @ RHIC (proposal) FOPI @ GSI (planning)
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7 modules, each ~1.5 x 1.5 m2
STAR data
RICH
High Momentum Particle IdentificationHigh Momentum Particle Identification
First Modulein production
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HMPID Proto-2: Excursion to BNLHMPID Proto-2: Excursion to BNL
Proto-2 @ CERN, tested in 1997
Arrival at BNL, August 1999 Into STAR, November 1999
July 2002: Back home again
STAR datapions
kaons
protons
p > 1 GeV
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ITS
TPC
TOF
Particle Identification performanceParticle Identification performance
HMPID
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dE/dx relativistic dE/dx relativistic rise ?rise ?
combine TPC and TRD dE/dx capabilitiescombine TPC and TRD dE/dx capabilities pion ID up to several 10 GeV ? K/p on a statistical basis ?
8<p<10GeV/c
RIKEN 10/2002 J. Schukraft43
Photons & LeptonsPhotons & Leptons PhotonsPhotons LHC: high particle density + large combinatorial background for 0, high granularity => dense material + large distance from vertex good resolution => scintillation crystals
compromise: acceptance ( ok for -> @ 1GeV)
MuonsMuons classical muon spectrometer (NA50, Phenix) high performance chambers: ~ 106 channels, very thin, small dead area goal: m/m ~ 1% @ 10 GeV (separate Y'')
challenge: integrate with central barrel ! very complex & sophisticated absorbers
Electrons Electrons (later addition to ALICE)(later addition to ALICE) combine TPC tracking with e-ID: Transition radiation detector TRD large area (800 m2) , high granularity (> 106 channels) challenge: triggering on high pt electrons
requires on-line tracking in < 6 s !!!
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for photons, neutral mesons and -jet tagging
PbW04: Very dense: X0 < 0.9 cmGood energy resolution (after 6 years R&D):stochastic 2.7%/E1/2
noise 2.5%/Econstant 1.3%
Photon SpectrometerPhoton Spectrometer
PbW04 crystal
single arm em calorimetersingle arm em calorimeter dense, high granularity crystals novel material: PbW04
~ 18 k channels, ~ 8 m2
cooled to -25o
RIKEN 10/2002 J. Schukraft45
PHOSPHOS mass production of crystals startedmass production of crystals started Apatity, Russia
Light Read-out Light Read-out APD's (Avalanche Photo Diodes) FEE still in design phase
PHOS 256-Channel Prototype
Collaboration:- Russia + Norway- China (tbc)Needs strengthening !
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• identify & trigger on electrons• used also in tracking• trigger on jets (high pt hardons)
largest chamber: 1200 x 1600 mm
Full scale prototype
currently ~ 60% funded
Transition Radiation DetectorTransition Radiation Detector
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Dimuon SpectrometerDimuon Spectrometer Study the production of the J/Study the production of the J/, , ', ', , , ' and ' and
'’ decaying in 2 muons, '’ decaying in 2 muons, 2.4 <2.4 < < 4 < 4 Resolution of 70 MeV at the J/Resolution of 70 MeV at the J/ and 100 MeV and 100 MeV
at the at the
Dipole Magnet: bending power 3Tm
Complex absorber/small angle shield system to minimize background(90 cm from vertex)
RPC Trigger Chambers
5 stations of high granularity pad tracking chambers, over 800k channels
RIKEN 10/2002 J. Schukraft48
Muon ChambersMuon Chambers Station 3-4: Slats
Trigger RPC
Station 1&2: Quadrants
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Muon MagnetMuon Magnet Dipole Magnet Dipole Magnet 0.7 T and 3 Tm 4 MW power, 800 tons World’s largest warm dipole
Progress:Progress: Coil production in progress in France Yoke finished end 2002 in Russia
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Proposed EMCAL||<0.7 ~ 120o
US proposal: large emcalUS proposal: large emcal large area electromagnetic calorimeter (a la STAR)large area electromagnetic calorimeter (a la STAR) hadronic energy in TPC + em energy in calorimeter trigger on jets, improve energy resolution, -jet coincidences (with PHOS)
(PT) ~15%
100 GeV Jet in Central PbPb
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T0L
Forward Forward DetectorsDetectors
V0 1.6 < |< 3.9 Interaction trigger (beam-gas rejection), centrality trigger and beam-gas rejection. Two arrays of 72 scintillator tiles readout via fibers
T0R 2.6 < || < 3.3 measure
event Time (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)
PMD pre-shower detector
2.3 < < 3.5, measures ncharged and nphotons
(DCC's)
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PMD for STARPMD for STAR
• STAR-PMD design is identical to ALICE-PMD TDR version• Fabrication mostly done – lab testing in progress• being installed – will be complete by Nov 2002
RIKEN 10/2002 J. Schukraft53
Zero Degree Zero Degree CalorimeterCalorimeter
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
First ZDC finished
6 small & dense calorimeters6 small & dense calorimeters trigger on impact parameter (spectators) located between 8m (em calo) and 116 m (ZP, ZN) from IP
RIKEN 10/2002 J. Schukraft54
High Level Trigger High Level Trigger (HLT)(HLT)
online PC farmonline PC farm FPGA co-processors in RORC ~ 500 - 600 dual CPU PC’s ~300 LDC’s (DAQ+HLT)~ 300 dedicated PC’s
test clusters running (Heidelberg, Oslo, Bergen) FPGA algorithm development
Task: BE FLEXIBLE !Task: BE FLEXIBLE ! selective R/O (RoI, eg e+e- pairs) event selection high mass lepton pairs (e, ) jets (high pt tracks)
data compression factor 2 to > 10 with online tracking in TPC
RIKEN 10/2002 J. Schukraft55
ALICE DC III
Computing Phase Computing Phase TransitionTransition
Online:Online: storing up to 1.2 Gbyte/s storing up to 1.2 Gbyte/s whole WWW in few hours on tape ! ~ 10 x RHIC !
Offline:Offline: 1800 kSI95 1800 kSI95 300,000 PC's in 2000 (500 Mhz) ~ 100 x RHIC !!
The Problem:
The Answer:
cheap mass market componentscheap mass market components Industry & Moore's law
The Challenge:
make 10,000 mice do the make 10,000 mice do the
work of one elephantwork of one elephant
new computing paradigm: The GRID
RIKEN 10/2002 J. Schukraft56
Performance Monitoring
ALICE Data ChallengesALICE Data Challenges
Regional TIER 1 TIER 2
DAQ
Simulated Data
ROOT I/OCERN TIER 0 TIER 1
Raw Data
GEANT3GEANT4FLUKA
AliRoot
CASTOR
GRID
ROOT
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ADC ADC Performance/plans:Performance/plans:
0
50
100
150
200
250
300
350
1999 2000 2001
DAQ
Mass Storage (sust)
Mass Storage (peak)
MB
/s
0
500
1000
1500
2000
2500
3000
1999 2000 2001 2002 2003 2004 2005 2006
DAQ
Mass Storage
MB
/s
RIKEN 10/2002 J. Schukraft58
2002: ADC IV Hardware Setup2002: ADC IV Hardware Setup
2 2 23 3 3 3
3 3 3 3
Total: Up to 192 CPU servers, Up to 36 DISK servers, 10 TAPE servers
2
10 TAPE servers(distributed)
CERN Backbone(4 Gbps)
8
TOTAL: 32 ports TOTAL: 18 ports
CPU servers on FE
TBED00 01-12 13-24 25-36 37-48
49-60 61-72 73-77
01D-12D13D-24D25D-36DLXSHARE
4 Gigabit switches 3 Gigabit switches
4 Gigabit switches
20 DISK serversCPU servers on GE
CPU servers on GE
90-100
RIKEN 10/2002 J. Schukraft59
ADC IV ADC IV performancesperformances
DATE event-building
1.8 Gbytes/s:
target 1 Gbyte/s
Data recording to disk
350 MBytes/s.
target 300 MBytes/s
Outperforming the plan, with commodity hardware!
In stable operation
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ADC II (2000)ADC II (2000)
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Yerevan
CERN
Saclay
Lyon
Dubna
Capetown, ZA
Birmingham
Cagliari
NIKHEF
GSI
Catania
BolognaTorino
Padova
IRB
Kolkata, India
OSU/OSCLBL/NERSC
Merida
Bari
The CORE GRID functionality existsThe CORE GRID functionality exists Distributed production in action for the PPRDistributed production in action for the PPR
ALICE GRID is there: ALICE GRID is there: ALIENALIEN
RIKEN 10/2002 J. Schukraft62
Production StatusProduction StatusTotal jobs per site
42%
15%
17%
5%
6%
1%
8%
2%4% 0%0%0%
0%
0%
CERN
Torino
LBL
Lyon
Catania
OSC
FZK
Padova
CNAF
GSI
Utrecht
Zagreb
Budapest
Prague
ALICE Productions
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
2001-02 2002-02 2002-03 2002-04
CPU
15100 jobs,~12CPUh/job, ~1GB output/job
up to 450 concurrently running
jobs
Number of concurrent jobs
0
50
100
150
200
250
300
350
400
450
500
2001-02 2002-02 2002-03 2002-04
Production round
#of jobs
Series1
RIKEN 10/2002 J. Schukraft63
Hadronic Observables IHadronic Observables Iparticle spectra (single event) two particle HBT correlations
multiplicity, pseudorapidity reconstructionreaction plane resolution
multiplicity in ALICE central detector
RIKEN 10/2002 J. Schukraft64
Hadronic Observables IIHadronic Observables II
K+K
p
K0 +-
Reconstruct (dN/dy~6k): ~
30 K0/central event ~ 3 /central event
p,K,K*, , D, d, T, , ..
RIKEN 10/2002 J. Schukraft65
Heavy Heavy QuarksQuarks
Hadronic charm: D -> KHadronic charm: D -> K uses sec. vertex & PID acceptance to ~ 0 pt => tot
full kinematic reconstruction => 'quark quenching'
under study: D*, D, Bc, b, ...
RIKEN 10/2002 J. Schukraft66
QuarkoniaQuarkonia
Acceptance Acceptance down to pt = 0
J/
J/
+-
e+e-
RIKEN 10/2002 J. Schukraft67
Di-MuonsDi-Muons
• M =94.5 MeV/c2
at the • Separation of , ’, “• Total efficiency ~ 75%• Expected statistics (significance – 1 yr): central min. bias J/ 310 574 ’ 12 23 39 69 ‘ 19 35 “ 12 22from min. bias events:~ 8k and ~700k J/ /yr
RIKEN 10/2002 J. Schukraft68
Jet QuenchingJet Quenching jet quenching = energy loss of leading particlejet quenching = energy loss of leading particle lost energy appears in soft particles => change of jet fragmentation function ! total jet-energy does not change ! => calorimeter only is insufficient
30-50 GeV 50-80 GeV
120-170 GeV
230-330 GeV
440-600 GeV
80-120 GeV
170-230 GeV
330-440 GeV
0 < pT < 50 GeV/c
Jet fragment pT distribution in jet cone
Normalized background pT distribution in jet cone
ALICE handles on jet quenchingALICE handles on jet quenching leading hadrons inclusive pt spectra & correlations identified hardons (, 0, , K)
leading heavy quarks inclusive b, c, D, B b, c tagging in jets (high pt electrons in TRD)
jet fragmentation function (TPC,TRD,emcal) correlations -jet (PHOS-emcal) jet1(emcal)-jet2(TPC)
RIKEN 10/2002 J. Schukraft69
SummarSummaryy
LHC is the LHC is the ultimate machineultimate machine for Heavy Ion Collisions for Heavy Ion Collisions very significant step beyond RHIC excellent conditions for experiment & theory (QCD) not only latest, but possibly last HIC at the energy frontier
ALICE is a powerful ALICE is a powerful next generation detectornext generation detector first truly general purpose HI experiment addresses most relevant observables: from super-soft to ultra-hard
many evolutionary developments SSD, SDD, TPC, em cal, …
some big advances in technology electronics, pixels, TOF, computing
Heavy Ion Community can look forward toeventually
exploit this unique combination !