Pixel baseline op.on: MAPS (state of the art: ALICE ALPIDE) - CERN Indico
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Pixel baseline op.on: MAPS (state of the art: ALICE ALPIDE)
1
ALICE ALPIDE performance
very good
very good
very good
very good
very good
reasonable
reasonable
2
Rate requirements for NA60+ sensor (vs ALPIDE)
Assume Pb-Pb interac.on rate: 1 MHz
o Max par.cle rate ≈ 100 MHz/cm2
Es.mate of flux hits/cm2s in pixel tracking
sta.ons based on Fluka simula.on with
primary π, K, p mbias mul.plici.es in Pb-Pb at
Elab=40 GeV
To be completed for Elab=160 GeV
Z=7 cm
Reading out all interac.ons:
o Max readout rate ≈ Readout rate ≈ 100 MHz/cm2
ALPIDE present performance
3
High rate opera.on (int rate ≈MHz) Con.nuous mode: readout of pixel hits sampled during periodically repea.ng strobing intervals, with a dura.on equal to the interval between two consecu.ve ones Framing intervals should be few hundred ns: strobe dura.on O(100 ns), strobe gaps O(100 ns) Chip priori.ses newly received frame requests over data that are already stored within the matrix è frame must be readout within few hundred ns (might be mi.gated by MEB) èSimula.ons of chip performance required 4
Present ALPIDE: Behavioural simula.on
o Matrix par..oned in 32 regions
(each 16 double-column), working
in parallel
o Region readout: ZS with priority
encoders, data compression,
storage in local buffer
o TRU: Local buffers read
sequen.ally for event building
sent to serializer
Behavioural simula.on:
o Input: hit rate/cm2 assuming
Poissonian int rate and hit
mul.plici.es from physics
o Performance in terms of:
• Framing intervals
• In-pixel MEB depth
• Region readout (based now on
PE at 20 MHz)
• Par..oning of regions (parallel
readout)
• Number of serializers 5
Large area sensor with S.tching
1.5x14 cm2 sensor: same column length as in ALPIDE (PE readout)
data are transmieed from the boeom of the columns along one long side of the
sensor to the periphery
Region control logic presumably at boeom of regions
6
periphery: contains the interfaces for the configura.on of the chip and serial data
transmieers
Large area sensor with S.tching
Technology: possibility to design in 65
nm TowerJazz
Explora.on of smaller pixels possible
è spa.al resolu.on of ≈ 1 µm possible
Thickness: 50 µm silicon
Wafer-scale sensor obtained replica.ng
this sensor chip several .mes along the
periphery side
≈5000 x 5000 pixels
Material budget and resolu.on crucial
in par.cular for open charm
è Further simula.ons with improved
material budget and resolu.on
ALICE ITS super-upgrade aier LS3
Expression of interest: Study of an almost “massless” ITS Inner Barrel based on the
s.ched sensors (upgrade foreseen during LS3)
8
The vertex spectrometer so far
Field integral: 1.2 Tm
3 T dipole
field along x
40 cm
Ø angular coverage down to η≈1.8 at 20
AGeV (ϑ~0.3 rad)
x
Ø 5 silicon pixel sta.ons at 7
Looking for exis.ng dipoles
AMS supercoduc.ng dipole
Not sent to space because too heavy
(did not meet NASA launch requirements)
Presently stored at CERN
Informal contacts established for possible use
10≈1 m
≈1 m
Dipole coils
≈1 m
Bx≈0.9 T x
Flux return coils
The magne.c dipole field is achieved by an arrangement of 14 superconduc.ng coils
The magnet system consists of a pair of large Helmholtz coils together with two series of six
racetrack coils, circumferen.ally distributed between them
All superconduc.ng coils are wound from a high purity aluminium-stabilized mono-strand NbTi
conductor with rectangular shape of 1.55 mm 2.00 mm
11≈1 m
Dipole coils
≈1 m
Bx≈0.9 T x
Flux return coils
The coils are located inside a toroidal-shaped vacuum vessel. They are indirectly cooled by
superfluid helium at 1.8 K
This cooling loop is thermally connected with a 2500 l vessel for superfluid helium which serves
as a cold reservoir
1213
Defining the geometry of tracking sta.ons
Small sta.ons
periphery
periphery
periphery
periphery
14
≈ 15 cmDefining the geometry of tracking sta.ons
Possibility of having beam passing through sensors?
periphery
periphery
periphery
periphery
15
≈ 15 cmDefining the geometry of tracking sta.ons
Large sta.ons: arrangement has
to be studied in detail
Tracking sta.on: one inner and
one external plane?
Support frames within
acceptance?
16
≈ 30 cmDefine requirements of vertex spectrometer
o Requirements for high rate opera.on: behavioural simula.ons of chip opera.on in
con.nuous mode
o Define dipole magnet (simula.on od AMS superconduc.ng dipole)
o Finalize requirements for material budget and resolu.on: inves.gate 50 µm/sta.on; spa.al
resolu.on ≈ 1µm
o Finalize pixel tracker in terms of tracking sta.ons (number/size)
o Define pixel planes in terms of possible arrangement of large area sensors
o Define system in terms of support frames, cooling, etc.
èFrom this qualita.ve drawing to a quan.ta.ve setup
17backup
18ALICE hybrids: NA60 workhorse
Ø Radia.on tolerant silicon pixel detectors became available only recently (original
slide wrieen in 2004)
Ø NA60 uses sensor + readout chips developed for the ALICE collabora.on
Pixel sensor
• 12.8 x 13.6 mm2 ac.ve area
• 32 x 256 cell matrix
• 50 x 425 µm2 cell size
sensor
15 mm ALICE1LHCb read-out chip
• Operated at 10 MHz clock
25 µm solder bump • Radia.on tolerant up to ~ 30 Mrad
• 32 columns parallel read-out 19
Read-out chip 14 mm 19ALICE hybrids: the
Dipole magnet
NA60 workhorse
Target system
Absorber
Beam Tracker
(micro-strips
operated at
130 K)
x8
Ø 12 tracking points with good acceptance
8 “small” 4-chip planes, plus
8 “big” 8-chip planes (4 tracking sta.ons)
x8 Ø ~ 3% X0 per plane
750 µm Si read-out chip
300 µm Si sensor
ceramic hybrid
NA60 pixel detector planes 20
Ø 800’000 R/O channels - 96 pixel assembliesState of the art : CMS(ATLAS) upgrades
21Pixel ROC
22Pixel sensor design parameters
23CMS forward pixel geometry
15 cm
160 readout chips organized in modules 232 readout chips organized in modules
24State of the art Hybrids: CMS(ATLAS) pixel
upgrades
25You can also read
