alice experiment detectors –photon spectrometer –central tracking detectors its, tpc, trd...
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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
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