hft pixel detector pre-practice cdr-1 review 3-sept.-2009 wieman 1
TRANSCRIPT
HFT PIXEL Detector
Pre-practice CDR-1 Review
3-Sept.-2009
Wieman
1
Topics
• Pixel detector system requirements and properties
• detector chip and readout development
• Mechanical development
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Pixel geometry. These inner two layers provide the projection precision
2.5 cm radius
8 cm radius
Inner layer
Outer layer
End view
One of two half cylinders
20 cm
coverage +-1
total 40 ladders
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Some pixel features and specificationsPointing resolution (13 22GeV/pc) m
Layers Layer 1 at 2.5 cm radiusLayer 2 at 8 cm radius
Pixel size 18.4 m X 18.4 m
Hit resolution 10 m rms
Position stability 6 m (20 m envelope)
Radiation thickness per layer
X/X0 = 0.37%
Number of pixels 436 M
Integration time (affects pileup) 0.2 ms
Radiation tolerance 300 kRad
Rapid detector replacement
< 8 Hours
criticalanddifficult
more than a factor of 2 better than other vertex detectors (ATLAS, ALICE and PHENIX)
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Monolithic Active Pixel Sensors
• Standard commercial CMOS technology • Only NMOS transistors inside the pixels• Room temperature operation• Sensor and signal processing are integrated in the same silicon wafer• Signal is created in the low-doped epitaxial layer (typically ~10-15 μm) → MIP signal is limited
to <1000 electrons• Charge collection is mainly through thermal diffusion (~100 ns), reflective boundaries at p-well
and substrate → cluster size is about ~10 pixels (20-30 μm pitch)• 100% fill-factor • Fast readout• Proven thinning to 50 micron
MAPS pixel cross-section (not to scale)
Detector chips developed by Marc Winter’s group at IPHC in Strasbourg, France
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Sensor generation and RDO attributes
Mimostar–2 30 µm pixel, 128 x 128 array1.7 ms integration time1 analog outputMimostar–330 µm pixel, 320 x 640 array2.0 ms integration time2 analog outputsPhase–130 µm pixel, 640 x 640 array640 µs integration time, CDS4 binary digital outputsFinal (Ultimate)18.4 µm pixel, 1024 x 1088 array≤ 200 µs integration time, CDS,zero suppression2 digital outputs (addresses)
Sensor Sensor RDO
50 MHz readout clockJTAG interface, control infrastructureADCs, FPGA CDS & cluster findingzero suppression ≤ 4 sensor simultaneous readout
160 MHz readout clockJTAG interface, control infrastructurezero suppression120 sensor simultaneous readout
150 MHz readout clockJTAG interface, control infrastructure400 sensor simultaneous readout(full system)
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2
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Silicon development
• Phase 1– for use in the engineering run– on pixel CDS– on chip discriminators– binary hit read out– integration time 640s
• Ultimate– for full installation run– functionality of Phase 1 plus zero suppression– integration time <200 s – suitable for full luminosity
operation7
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HFT PIXEL MAPS120 GeV π- beam test at CERN
Efficiency and Fake hit rate for Mimosa-16. 25um pixels at 20º C. This is the sensor design that is the basis for the HFT Phase-1 Pixel sensors.
Efficiency and Fake hit rate for Mimosa-22. This sensor has the same design as the final HFT Pixel sensor. This sensor has been tested to 150k rad and maintained 99.5% efficiency with < 10-4 fake hit rate.
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Phase - 1
• Extensively tested and characterized by the LBNL group– Multiple chips have been studied doing scans of operating
parameters to determine optimum operation mode and determine permissible operation limits
– Readout, firmware, testing tools mature, ready for probe testing of diced and thinned chips
– so far ~100% yield of chips sampled from different locations on the wafer
– Noise levels suitable for engineering run, but potential improvements have been identified and a second run is planned
– near future – build a multi chip telescope and test in a minimum ionizing beam
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640 x 640 pixels, 30 um pitch, 160 MHz RDO clock, column level discriminators, 4 binary outputs, 640 us integration time
Phase-1 – full reticle binary output prototype
Phase-1 prototype sensors have been fabricated and tested at LBNL
Phase-1 prototype on testing board. Initial observations of Phase-1 operation
Digital output
Analog output
Example parameter scan (Vref2)
(one half of the chip seems to be sensitive to the parameter value)issue to be studied further at IPHC to understand cause
Chip D1 (parameter scan)VREF2 = 81 0.887 VVREF2 = 82 0.898 VVREF2 = 83 0.909 VVREF2 = 84 0.920 VVREF2 = 85 0.931 V(@ ICLPDISC = 80)
Mean noise value
Threshold dispersion
Discriminator threshold voltage identified by 50% pixel hits (half below threshold half above threshold)
Ultimate status
• design is nearing completion
• will be submitted for first fabrication Feb 2010
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Readout studies: LVDS Data Path Testing•Significant test of system data path at up to 200 MHz with 3 streams of pseudo-random data•Xilinx Virtex-5 IODELAY element allows fine tuning of all individual input latching in 75 ps increments. Only system jitter affects data latching.•Measured BER (bit error rate) of <10-14 for 1 m 42 AWG and 6 m twisted pair data cables at 200 MHz and for 2.3 m 42 AWG at 160 MHz.•The RDO system architecture is considered to be validated and we then worked on the design of the full functionality prototype system.
2 ns eye patternopening for 1 m 42 AWG cables at 200 MHz
Ladder mock-up with 1-to-4 LVDS fanout buffers
Mass termination board + LU monitoring
42 AWG wires
24 AWG wires
Virtex-5 based RDO system with RORC link to PC
http://rnc.lbl.gov/hft/hardware/docs/LVDS/LVDS_test_report_1.pdf
current readout development work
• Preparing for probe test
• Develop multi chip readout capability (a modification of the current system)
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HFT PIXEL mechanical development
• Stability analysis
• Thermal analysis
• Air flow vibration tests
• Thermal tests
• Fabrication development
• Installation mechanics
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vertex projection from two points
212
21
22
rr
rrxv
0
6.13X
pc
Mevm
1rv m detector layer 1
detector layer 2
pointing resolution = (13 22GeV/pc) m
fromdetectorpositionerror
fromcoulombscattering
r2r1
true vertexperceived vertex
x
x
v
r2r1
true vertexperceived vertex
v
m
expectations for the HFT pixels
%37.00 X
first pixel layer
more than 3 timesbetter than anyoneelse
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Mechanical Stability
• Movement from temperature changes• Movement from humidity changes• Deflection from gravity• Movement induced by cooling air (to be
addressed after thermal discussion)– how much air is required– vibration and static displacement
Once the pixel positions are measured will they stay in the same place to within 20 µm? Issues that must be addressed:
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Stability requirement drives design choices
• The detector ladders are thinned silicon, on a flex kapton/aluminum cable
• The large CTE difference between silicon and kapton is a potential source of thermal induced deformation even with modest 10-15 deg C temperature swings
• Two methods of control– ALICE style carbon composite
sector support beam with large moment of inertia
– Soft decoupling adhesive bonding ladder layers
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Ladder design with soft adhesive (6 psi shear modulus)
cable bundle
drivers
pixel chips
adhesive
wire bonds
capacitors
adhesive
composite backer
kapton flex cable
adhesive:3M 200MP2 mil, film adhesive
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FEA analysis of thermally induced deformation of sector beam
• FEA shell elements• Shear force load
from ladders • 20 deg temperature
rise• Soft adhesive
coupling• 200 micron carbon
composite beam• end cap
reinforcement• Maximum
deformation 9 microns (30 microns if no end cap)
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FEA analysis - sector beam deformation – gravity load
• FEA shell analysis• 120 micron wall
thickness composite beam
• gravity load includes ladders
• maximum structure deformation 4 microns
• ladder deformation only 0.6 microns
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Air cooling of silicon detectors - CFD analysis
air flow path – flows along both inside and outside surface of the sector
• Silicon power: 100 raised to 170 mW/cm2 (~ power of sunlight)
• 350 W total Si + drivers
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Air cooling – CFD analysis• air flow velocity 9-10 m/s• maximum temperature rise above
ambient: 12 deg C• sector beam surface – important
component to cooling• dynamic pressure force 1.7 times
gravity
stream lines with velocity
silicon surface temperature
velocity contours
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vibration modes with reinforced end cap
• The message– Lots of complicated modes
close in frequency
– End cap raises frequencies a bit
259 Hz
397 Hz
276 Hz
441 Hz
497 Hz
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air velocity probetwo positions shown
capacitance vibration probetwo positions shown
carbon fiber sector beam
wind tunnel setup to test vibration and displacement
adjustablewall for airturn around
air in
air out
C:\Documents and Settings\Howard Wieman\My Documents\aps project\mechanical\PXL phase 1 sept 2008\sector ph1 wind tunnel.SLDASM
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Ladder vibration induced by cooling air
30m
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20m
12
system resolution limitall errors
desired vibration target
0 2 4 6 8 10 120
2
4
6
8
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measured vibration with negative pressure modemeasured vibration with positive pressure mode
Ladder Vibration
air velocity (m/s)
vibr
atio
n R
MS
(m
icro
ns)
5.77
8.66
8
no reinforcement at the end
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-167 µm
6 µm
17 µm17 µm
-179 µm
-248 µm
measured static deformation from 9 m/s air flow
-156 µm
-163 µm-113 µm
9 µm11 µm
1 µm
open end
reinforcedend
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measured vibration (RMS) induced by 9 m/s air flow
13 µm14 µm
14 µm
4 µm 6 µm6 µm
8 µm
3 µm3 µm
2 µm
11 µm
4 µm
openend
reinforcedend
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Full scale cooling tests
Thermal camera window not shown
> 300 CFPM air flow for verification of cooling capability
9 inch diameter tube mocks up MSC
29dust collector for air supply
cooling test setup
• ladders with heaters mocking up expected heat loads– Flex pc with heater traces on
most surfaces
– One sector with ladders equipped with 50 micron silicon with platinum heater strip
– ladders equipped with thermistor temperature sensors
– thermal camera monitoring thinned silicon heaters
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12.2 m/s, ~300 W
Thermistor temperature map for all the ladders on the inner and outer cylinders
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Thermal test results
Hot spots for images at location 0-21 cm (3 cm step): 41.2, 42.5, 41.4, 41.6, 41.4, 40.5, 40.1, 38.3 ºC
“sensor” heaters: ~230 W
Pt heaters: ~25 W
Driver heaters: ~40 W
Total: ~295 W
Airflow 12.2 m/s
max
min
room
∆T above ambient room temperature: 11.5 deg C
Temperature in hot spots and averaged across approximately a die surface(location at 3 cm)
y = -1.2076x + 55.904
y = -1.2924x + 55.224
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50
6 7 8 9 10 11 12 13
airflow (m/s)
sili
con
tem
per
atu
re (
ºC)
hot spot
average
Linear (hot spot)
Linear (average)
input air temperature ~31 ºC
Silicon temperature as a function of cooling air velocity
Thermal test conclusions
• Results reasonably consistent with CFD calculations
• Can handle the increased heat load of sensors with 30% increased air flow
• Need to recheck vibration with this 30% increase in air velocity
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Ladder and sector manufacturing
• Tooling has been developed and tested for efficient fabrication of ladders and bonding of ladders to sectors
• Sector production demonstrated, will possibly work on improved shape control
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Sector structures
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ladder fabrication and tooling
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ladder fabrication and tooling
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ladder fabrication and tooling
39finalizing mechanical designs and developing rapid production methods
ladder fabrication and tooling
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ladder withsilicon heaterchips(50 m thick)
wire bonding 50 m silicon to flex PC
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vacuum chuck tosecure flex and siliconflat against solid surfaceto remove bounce
Any bounce then no bond
Good Newsafter a couple of minor modifications to the vacuum chuck thewire bonding machine is happyRhonda is happy
ladder to sector tooling fixtures (4 stations)
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Designs for installation of PXL
• a well controlled method for installation of the pixel detector is being developed with emphasis on ease of operation and avoidance of detector risk
• The PXL assembly will be enclosed in a carrying box that is equipped for transfer of the detector assembly into the PXL support tube
• The operation should work with and without the pole tip installed
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PXL installation
• PXL supported in carrying box on rails
• assembly designed to position around beam pipe and supports
• box can moved into the MSC such that rails in the box couple to the support rails in the MSC
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box positioning video
box alignment and PXL transfer• box positioned to align
rails, but rails have a slightly flexible joint so that less than perfect alignment is required to move box forward to engage taper pins
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with rails connected, slide PXL until carriage is engaged on the MSC rails
final installation steps
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remove box rails
slide detector home
remove box and connect services