howard matispixel 20051 a high resolution vertex tracker for the star experiment using active pixel...
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Howard Matis Pixel 2005 1
A High Resolution Vertex Tracker for the STAR Experiment using Active Pixel Sensors
andRecent work using APS Sensors
A High Resolution Vertex Tracker for the STAR Experiment using Active Pixel Sensors
andRecent work using APS Sensors
F. Bieser, R. Gareus, L. Greiner, J. King, J. Levesque, H.S. Matis, M. Oldenburg, H.G. Ritter, F. Retiere, A. Rose, K. Schweda, A. Shabetai, E. Sichtermann, J.H. Thomas, H. Wieman, Lawrence Berkeley National Laboratory
S. Kleinfelder, S. Li, University of California, Irvine
H. Bichsel, University of Washington
F. Bieser, R. Gareus, L. Greiner, J. King, J. Levesque, H.S. Matis, M. Oldenburg, H.G. Ritter, F. Retiere, A. Rose, K. Schweda, A. Shabetai, E. Sichtermann, J.H. Thomas, H. Wieman, Lawrence Berkeley National Laboratory
S. Kleinfelder, S. Li, University of California, Irvine
H. Bichsel, University of Washington
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physics motivation for a thin vertex detectorphysics motivation for a thin vertex detector
Study initial properties of a nuclear collision
u, d, s quarks gain mass become thermalized Final state effects Measures later/cooler
times of the collision d, b quarks produced at
early time Intrinsic mass Measure of early
collision
Study initial properties of a nuclear collision
u, d, s quarks gain mass become thermalized Final state effects Measures later/cooler
times of the collision d, b quarks produced at
early time Intrinsic mass Measure of early
collision
deconfinement
Phase and Chiral transitions
u-, d-quarks and ‘bound-states’ gain mass
PART I - DETCTOR
Need to measure particles above 0.5 GeV/c High collision density - more than 2000 tracks
Measures secondary particles >100 µm from collision point
Need to measure particles above 0.5 GeV/c High collision density - more than 2000 tracks
Measures secondary particles >100 µm from collision point
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detector requirementsdetector requirements
Study D0 measurement Multiple scattering in
beam pipe sets fundamental limits
“Dream” Detector Thickness 240 µm Si
equivalent Position resolution 8
µm
Study D0 measurement Multiple scattering in
beam pipe sets fundamental limits
“Dream” Detector Thickness 240 µm Si
equivalent Position resolution 8
µm
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star micro vertex detectorstar micro vertex detector
Two layers 1.5 cm radius 4.5 cm radius
24 ladders 2 cm 20 cm each < 0.3% X0
~ 100 Mega Pixels
Two layers 1.5 cm radius 4.5 cm radius
24 ladders 2 cm 20 cm each < 0.3% X0
~ 100 Mega Pixels
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close-up viewclose-up view
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sensorsensor
Efficiency for min ionization 98%
Accidental rate < 100 /cm2
Position resolution < 10 m
Pixel dimension 30 m 30 m
Detector chip active area 19.2 mm 19.2 mm
Detector chip pixel array 640 640
•Sensor under development at IReS•First prototype made using 0.25 µm process by TSMC•Second version in production using 0.35 µm by AMS
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ladderladder
10 thinned APS detectors Top of a matching row of
thinned readout chips Three-layer aluminum
Kapton cable Silicon cable structure is
bonded to a carbon composite v, closing the beam to make a rigid structure
Wire bonding to the cable
10 thinned APS detectors Top of a matching row of
thinned readout chips Three-layer aluminum
Kapton cable Silicon cable structure is
bonded to a carbon composite v, closing the beam to make a rigid structure
Wire bonding to the cable
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ladderladder2 carrier candidates – X0 =0.11 %
Top layer = 50 µm CFC
Middle layer = 3.2 mm RVC
Bottom layer = 50 µm CFC
Outer shell = 100 µm CFC (carbon fiber composite)
Fill = RVC (reticulated vitreous carbon foam)
RDO Chip
APS
Cable
Carrier
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ladder prototypesladder prototypes
Mechanical Prototype with 4 MIMOSA-5 detectors glued to the Kapton cable assembly. Tested for Vibration Stiffness
• A prototype cable (Cu) has been designed, constructed and tested.
• Prototype ladder using thinned 50 µm MIMOSA-5 detectors. Currently under test with DAQ
Mechanical Prototype with 4 MIMOSA-5 detectors glued to the Kapton cable assembly. Tested for Vibration Stiffness
• A prototype cable (Cu) has been designed, constructed and tested.
• Prototype ladder using thinned 50 µm MIMOSA-5 detectors. Currently under test with DAQ
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heavy flavor tracker (hft) parametersheavy flavor tracker (hft) parameters
Total number of pixels 98 106
Number of pixels per chip 640 x 640
Pixel Readout rate 100 ns
Readout time per frame 4 ms
Dynamic range of the ADC 10 bits
Raw data from one sensor using a 10 bit ADC 1 Gb/s
Fixed pattern noise 2000 e
Noise after Correlated Double Sampling 10 e
Maximum signal 900 e
Dynamic range after Correlated Double Sampling 8 bits
Total power consumption 90 W
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mechanical requirementsmechanical requirements
Geometry Maintain position resolution of ~ 10 µm Low mass / radiation length (X0~ 0.3% / layer) Coverage of -1 < < 1
Function
• Easy to calibrate
• Easy to align
• Easy to remove, repair and replace electronics (ladders will need to have a local survey)
• Fit easily into the existing detector and infrastructure at STAR
Geometry Maintain position resolution of ~ 10 µm Low mass / radiation length (X0~ 0.3% / layer) Coverage of -1 < < 1
Function
• Easy to calibrate
• Easy to align
• Easy to remove, repair and replace electronics (ladders will need to have a local survey)
• Fit easily into the existing detector and infrastructure at STAR
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conceptual mechanical designconceptual mechanical design
•Mounted to SVT cone
•Slides in and out on one end
•Ladders moves as beam pipe diameter increases
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kinematic support structurekinematic support structure
•Support bolts unto STAR
•Green structure provides stable support for the ladder
•Three point kinematic mounts assure accurate positioning
•Can move detector in and out with reproducibility
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studies with scanning electron microscopestudies with scanning electron microscope
12 µm
Access to 5 - 30 keV scanning electron microscopeThought needed to punch through 2-3 µm Believed could detect these electrons
PART II - APS RESEARCHPART II - APS RESEARCH
30 keV electrons
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cross sectional view(Tilt at 520)
cross sectional view(Tilt at 520)
Pt Layer
Top of ICArtifact dueto charge
Epi-layer
Top coating
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element analysiselement analysis
AlAl
TiTi
WW
PtPt
SiSi
OOGaGa
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30 kev electrons do not penetrate to the epilayer30 kev electrons do not penetrate to the epilayer
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can detect “electrons” with reasonable accuracy
can detect “electrons” with reasonable accuracy
Can see microscope Measuring
Bremsstrahlung Maximum intensity
~3000 /frame
Evaluate charge sharing of cell
Evaluate position resolution algorithms Best
Can see microscope Measuring
Bremsstrahlung Maximum intensity
~3000 /frame
Evaluate charge sharing of cell
Evaluate position resolution algorithms Best
µm
x3 x1
x1 x2 /2 x3
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track efficiency is critical with noise leveltrack efficiency is critical with noise level
Monte Carlo study two different algorithms with MIMOSA 5 Look for seed pixels Smooth data and then
look for seed pixels Real pedestal data with
imbedded electron spectrum Efficiency algorithm
dependent Algorithm choice dependent
on noise
Monte Carlo study two different algorithms with MIMOSA 5 Look for seed pixels Smooth data and then
look for seed pixels Real pedestal data with
imbedded electron spectrum Efficiency algorithm
dependent Algorithm choice dependent
on noise
Howard Matis Pixel 2005 20
how much signal do you get out of an aps sensor?how much signal do you get out of an aps sensor?
Calculations show that energy loss in thin materials much less than thicker Bichsel & Saxon, Phys.
Rev. A 11, 1286 (1975).
Observed in aluminum Perez & Sevely, Phys.
Rev. A 16, 1061 (1977).
Calculations show that energy loss in thin materials much less than thicker Bichsel & Saxon, Phys.
Rev. A 11, 1286 (1975).
Observed in aluminum Perez & Sevely, Phys.
Rev. A 16, 1061 (1977).
Energy Deposited - eV
Landau
Bichsel & Saxon
0.76 µm Al1 MeV e-
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study at lbnl advanced light sourcestudy at lbnl advanced light source
Study 1.5 GeV/c electrons
Calculated expected energy Use Bichsel formalism 0.25 µm TSMC 8 µm epitaxial layer
Need to shift theory by 1.5 for good agreement
Study 1.5 GeV/c electrons
Calculated expected energy Use Bichsel formalism 0.25 µm TSMC 8 µm epitaxial layer
Need to shift theory by 1.5 for good agreement
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some checkssome checks
Epitaxial (epi) layer 8 µm (error perhaps 1 µm)
Use Bichsel formalism on 8.5 µm aluminum data 1.66 keV scales to 1.43
keV silicon (most probable)
Bichsel predicts 1.43 keV
Total systematic error 10 - 20 %
Cannot explain 50% excess
Epitaxial (epi) layer 8 µm (error perhaps 1 µm)
Use Bichsel formalism on 8.5 µm aluminum data 1.66 keV scales to 1.43
keV silicon (most probable)
Bichsel predicts 1.43 keV
Total systematic error 10 - 20 %
Cannot explain 50% excess epitaxial layer
p++
substrate
P epitaxial layer
n-wellp-well MIP
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a hypothesisa hypothesis
Extra charge equivalent to 4 µm
Electrons could be coming from upper p-well and p++ substrate
Check with Mimosa-5 data (AMS 0.6 µm) Most Probable - 996 e-
Bichsel - 746 e-
Equivalent to extra 4.7 µm over nominal 14 µm
Extra charge equivalent to 4 µm
Electrons could be coming from upper p-well and p++ substrate
Check with Mimosa-5 data (AMS 0.6 µm) Most Probable - 996 e-
Bichsel - 746 e-
Equivalent to extra 4.7 µm over nominal 14 µm
p++ substrate
P epitaxial layer
n-wellp-well MIP
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scaling of cell sizescaling of cell size
UCI design a multi-spacing chip 5 µm, 10 µm, 20 µm and
30 µm All cell sizes on one chip
Minimize systematic errors
Charge sharing very similar Can see small absorption of
charge in epitaxial layer Good scaling
UCI design a multi-spacing chip 5 µm, 10 µm, 20 µm and
30 µm All cell sizes on one chip
Minimize systematic errors
Charge sharing very similar Can see small absorption of
charge in epitaxial layer Good scaling
5 10
20 30
Linear Scale
5 10
20 30
Log Scale
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summarysummary
Proposal for a vertex detector with APS technology Awaiting funding Transmission scanning microscopes can be used
to probe sensors Software algorithms important to get high hit
reconstruction - choice very sensitive to absolute noise
Cell scales from 5 to 30 µm More charge then expected coming from APS
Proposal for a vertex detector with APS technology Awaiting funding Transmission scanning microscopes can be used
to probe sensors Software algorithms important to get high hit
reconstruction - choice very sensitive to absolute noise
Cell scales from 5 to 30 µm More charge then expected coming from APS
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A Heavy Flavor Tracker for STAR
Z. XuBrookhaven National LaboratoryY. Chen, S. Kleinfelder, A. Koohi, S. Li University of California, IrvineH. Huang, A. TaiUniversity of California, Los AngelesV. Kushpil, M. SumberaNuclear Physics Institute AS CRC. Colledani, W. Dulinski, A. Himmi, C. Hu, A. Shabetai, M. Szelezniak, I. Valin, M. WinterInstitut de Recherches Subatomique, StrasbourgM. Miller, B. Surrow, G. Van NieuwenhuizenMassachusetts Institute of TechnologyF. Bieser, R. Gareus, L. Greiner, F. Lesser, H.S. Matis, M. Oldenburg, H.G. Ritter, L. Pierpoint, F. Retiere, A. Rose, K. Schweda, E. Sichtermann, J.H. Thomas, H. Wieman, E. YamamotoLawrence Berkeley National LaboratoryI. KotovOhio State University
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endend
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backup slidesbackup slides
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precision tie points coupling the hft system to the star support coneprecision tie points coupling the hft system to the star support cone
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thin beam pipethin beam pipe
Central beryllium region 14.5 mm radius
10 beam size 500 µm thick walls
Outer region 30 mm radius aluminum
Exoskeleton caries load
Central beryllium region 14.5 mm radius
10 beam size 500 µm thick walls
Outer region 30 mm radius aluminum
Exoskeleton caries load
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end view showing the hft ladders between spokes of the inner beam pipe supportend view showing the hft ladders between spokes of the inner beam pipe support
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data flow and processing stages in the readout chipdata flow and processing stages in the readout chip
Each stage can be bypassed to allow raw or partially unprocessed data to be routed to the DAQ
The first stage is a CDS preprocessor which is followed by pedestal subtraction and a pixel masking filter
Further processing allows us to sum up the value of 1, 4 or 9 pixels before a threshold cut is applied.
The last stage includes zero suppression and transcoding to hit positions.
Each stage can be bypassed to allow raw or partially unprocessed data to be routed to the DAQ
The first stage is a CDS preprocessor which is followed by pedestal subtraction and a pixel masking filter
Further processing allows us to sum up the value of 1, 4 or 9 pixels before a threshold cut is applied.
The last stage includes zero suppression and transcoding to hit positions.
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readout layoutreadout layout sketch of the
readout-topology on a detector ladder
one of ten APS and the corresponding readout chip layout.
sketch of the readout-topology on a detector ladder
one of ten APS and the corresponding readout chip layout.
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rdo asicrdo asic
• ADC – 10 bit ADC for signals from sensor chip
• CDS – Chip will perform correlated double sampling
• High speed LVDS output
• Configuration, control, clock, synch functions
• ADC – 10 bit ADC for signals from sensor chip
• CDS – Chip will perform correlated double sampling
• High speed LVDS output
• Configuration, control, clock, synch functions
• Both chips thinned to 50 µm thickness.
• X0 = 0.053 % each
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daqdaq
Figure5:
ladders can be combined to one optical link.
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hit loadinghit loading Au+Au Luminosity 1 1027 cm-2s-1
dN/d (min bias) 170
Min bias cross section 10 barns
Interaction diamond size, σ
30 cm
Outer Layer Inner Layer
Radius 5 cm 1.5 cm
Hit Flux 4.3 kHz/cm2 18 kHz/cm2
Hit Density 4 ms Integration 17/cm2 72/cm2
Projected Tracking Window Area 0.6 mm2 0.15 mm2
Probability of Tracking Window Pileup
10 % 10 %
HFT Hit Resolving Area 0.001 mm2 0.001 mm2
Probability of HFT Pileup 0.14% 0.58%
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Comparison with mimosa-5Comparison with mimosa-5
Parameter Detector MIMOSA-5
Detection efficiency 98% @30 – 40 C ~ 99% ≤ 20 C
resolution < 10 µm ~ 2 µm
pixel pitch) 30 µm 17 µm
Read-out time 4 – 10 ms 24 ms ( 20 ms possible)
Ionizing radiation tolerance
2.6 kRad/yr 100 kRad
Fluence tolerance 2 1010 neq/cm2 ≤ 1012 neq/cm2
Power dissipation 100 mW/cm2 ~ 10 mW/cm2
Chip size ~2 2 cm2 1.9 1.7 cm2
Chip thickness 50 m 120 m
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material budgetmaterial budget
MaterialMaterial Thickness
(µm of Si)% X0
Beryllium beam pipe 500 µm of Be 0.1417
MIMOSA detector 50 0.0534
Adhesive 13 0.0143
RDO chip 50 0.0534
Adhesive 13 0.0143
Cable assembly 84 0.0896
Adhesive 13 0.0143
Carbon fiber / RVC beam 103 0.1100
Total for the ladder components
327 0.349
Howard Matis Pixel 2005 39
using an aps as a camerausing an aps as a camera