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Staves:
An Integrated Tracking Structure for
the ID
Carl Haber
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Outline
• Issues from Genoa
– Derived specifications
• Progress on Phase 1 program
• Plan for future work
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Genoa Meeting
• Basic configuration “consensus”
– Pixel region
– Intermediate region: 3 SS layers 3cm x 80mm
– Outer region: 2 DS layers ~10cm x 150mm,
• Z measurement provided by stereo
• Radiation issues: implication for S/N and
operating temperature
– ~-25C suggested
• Strong emphasis on material and services
reduction: alternate powering schemes
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Basic Genoa Layout
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pixel region
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2 Types of Staves
16 modules/side
18 modules/side
• 20<R<50cm: 1 meter stave, 6.4 x 3 cm strips, alternate along
Z, top/bottom provides full coverage
• R>50cm: 2 meter stave, 6.4 (12.8) x 12 cm strips,
axial/stereo – top/bottom design to provide Z at large radius
– Width driven by economics and electrical issues (voltage drops…)
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Mechanical Core
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Stave End View
Silicon Sensors
4mm separation
Peek Cooling
channels
2.9 x 5.6 mm
Carbon Fiber Skin
Hybrid electronics
Foam Core
Material/stave:
• 1.8% RL
•(compare 2.5% ATLAS)
• 124 grams
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Fraction of Total RL:
• Hybrids 13%
• Sensors 39%
• Bus Cable 17%
• CF/Coolant 29%
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Integrated
support
structure:
2 int bulkhead
3 outer bulkheads
2(3) barrels
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Structure with one
outer barrel and
maximum of 1 meter
unsupported staves
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Details of CDF Bulkhead
See stave core mechanical samples
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Stave Specifications
• Electrical
– Power distribution
– Signal transmission
– HV
• Mechanical: advocate a monitored approach with
software corrections implicit. There are many
examples of large scale precision systems done that
way.
– Accuracy in plane
– Sag effects
– Operating temperature and gradients
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10-Nov-2005
Property
Short stave
Long Stave
width
6.4 cm
6.4 cm (12.8 cm)
length
98 cm
192 cm
detector width
6.4 cm
6.4 cm (12.8 cm)
detector length
3 cm
12 cm
detectors per side
18
16
gap between detector along the stave
2.4 cm
3 mm
detector thickness
280 microns
300 microns
number of strips
768
384 (768)
strip pitch
80 microns
160 microns
Power in front end chips
3 watts
1.7 watts (3.3 watts)
Power in silicon – no dose
1 milliwatt
1 (2) milliwatt
Power in silicon – high dose
1 watt
1 (2) watt
Maximum temperature at silicon
-25 C
-10 C
Maximum temperature variation
<5 C
<5C
Max detector position shift from nominal Dy
30 microns
30 microns
Max detector position shift from nominal Dx
30 microns
30 microns
Survey accuracy Sy
5 microns
5 microns
Survey accuracy Sx
10 microns
5 microns
Survey accuracy Sq
0.13 mRad
0,13 mRad
Ladder sag maximum
250 microns
500 microns
Ladder sag stability
50 microns
50 microns
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Operating Temp – S/N
• At Genoa values quoted -15 to -25 C
• Depends on how the spec’d S/N (10?) is
achieved, many variables at play
–
–
–
–
–
Leakage current vs dose well known
Silicon thickness
CCE, orientation (n in p, n in n, p in n)
Strip pitch: cluster size, capacitance
FE noise, integration time
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Continued…
• p bulk gives us high field at collection, good for CCE
issue
• Wide pitch (150 um) gives us large volume for
current generation (bad) but favors single strip
clusters (good), and lower capacitance
• Fast electronics allows us to reduce integration time
(good for shot noise) but has larger series noise (bad,
but how bad?) and required more power (bad for
cooling).
• Etc….
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Comments on Monitoring
• Stave sag and other deformations
(temperature) will be present
• Position monitoring and readout should be
designed into the system from the start.
– A number of precise and long range position
sensing technologies are commercially available
• We should be prepared to apply software
corrections to the alignment extensively
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Phase 1 Stave
•An ATLAS version of the CDF Run2b device
•1 sensor + hybrid = 1 module (hybrid glued to Si)
• 6 modules per side
• Modules linked by embedded bus cable and
readout token passing scheme
• 2 sided – axial/stereo or axial/axial
• 1 Interface Card /stave
• Total length 66 cm
• 6144 channels /stave
•Built around carbon fiber/foam laminate
Purpose is do demonstrate low noise multi-module performance with ATLAS electronics
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Phase 1 Milestones (completion dates given):
full electrical specification and schematic for Phase 1 stave
10/04
done
establishment of test stands at LBNL, BNL, and Hampton
11/04
done
validation of test stand operation on test parts
12/04
done
design and layout of Phase 1 hybrid
12/04
done
fabrication of hybrid
03/05
done
assembly and test of hybrid
04/05
done
re-commission and tests with existing fixtures
03/05 done
assembly of ATLAS staves
06/05
11/05
initial test of ATLAS staves at LBNL
07/05
11/05
transfer to and test of staves at BNL/Hampton
08/05
12/05
irradiation studies of staves
10/05
02/06
transfer of assembly methods to BNL
07/05
12/05
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Bus cable detail shows bonding region
The bus cable runs UNDERNEATH the sensors. Connections to the
hybrids made with wirebonds in small Z gaps between consecutive
crystals
Bus cable is copper/kapton/Al laminate with 100 micron lines/spaces
and thin Al shield layer
Electrical isolation of bus from detectors by grounded shield and
diagonal traces (not parallel to strips)
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ABCD Hybrid
• Fabricated in BeO
• Fine pitch (100 micron)
etched line-work
• 7 micron Au thickness
• Bond to pc card for test
• Re-bond on stave
• No connectors
• Schematic similar to
standard SCT hybrids
• Electrically OK
• 64 fabricated
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Module Assembly/Hybrid Mount
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Module Test
Conducting rubber
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Main Technical Issue: Clock Distr.
• Existing bus cable design: individual clock/com to each of 6
modules
• This was at the edge of practicality (layout)
• Genoa: long staves with N  modules
• Prefer to use a multidrop configuration

–
–
–
–
This may be the only practical solution for longer staves
Stave bus cable has been redesigned, layout revision in progress
Timing and reflections have been studied
Implications for ABCD-Next design, etc.
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Bus Cable Geometry and Impedance
Materials: Al foil 2mil, Dupont LF0100, Shinetsu CA333 2 mils, Cu 18 um,
Kapton 1 mil, Adhesive
2
Al
1
1
~1
ADHESIVE
Cu
0.7
1
1
KAPTON
CF
>>Matches measured impedance
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Issue of timing
•
•
•
•
Hybrid stubs = 12 pf
LVDS risetime = 3.5 ns
Bandwidth = 0.35/3.5 = 100 MHz
Impedance of hybrid stub due to capacitance
• 1/(2pi * 100 MHz * 12 pf) = 130 ohms
• Propagation time = 60 ps/cm (3 ns for 50 cm)
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Measurements
• Literature available on
LVDS multidrop
performance
– Application reports from TI,
National, Fairchild…
– TI study of 36 receivers
• Need to understand this
configuration as part of the
ongoing study
– Significant impact on
cabling
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40 MHz, No Bus
Bus Cable Test
4.00E-01
3.00E-01
2.00E-01
1.00E-01
Series1
0.00E+00
-1.00E-01 1
50 99 148 197 246 295 344 393 442 491
No Bus
-2.00E-01
-3.00E-01
75 W
termination
-4.00E-01
12+12 W
40 MHz at pos 5
40 MHz, at pos 1
40 MHz at pos 3
4.00E-01
4.00E-01
3.00E-01
3.00E-01
4.00E-01
3.00E-01
2.00E-01
2.00E-01
2.00E-01
1.00E-01
1.00E-01
Series1
0.00E+00
-1.00E-01
1
57 113 169 225 281 337 393 449
ref 3 at pos 5
1.00E-01
Series1
ref2 at pos 3
0.00E+00
1
56 111 166 221 276 331 386 441 496
-1.00E-01
-1.00E-01
-2.00E-01
-3.00E-01
-2.00E-01
-3.00E-01
-4.00E-01
-3.00E-01
-4.00E-01
-2.00E-01
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Series1
0.00E+00
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54 107 160 213 266 319 372 425 478
ref1 at pos 1
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Implications
• Bus cable test results imply that Phase 1 test stave with 6
hybrids (4 ABCD chips/hybrid) will probably work with a
single clock line.
• For large N staves need to consider an LVDS receiver chip at
the hybrid input to reduce capacitance seen by the bus drivers
• This is consistent with reduced services model
–
–
–
–
AC coupling
Regulators
Current monitor
Addressing issues (A.G. note)
• The module receiver chip (MRC) definition and specification
should become an important aspect of the ABCD-next
discussion.
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Continued Activity FY06
• Complete Phase 1 stave
– Apply a multidrop configuration
• Alternative powering: add to a second version of the Phase 1 stave
– Serial
– DC-DC?
– Study of bussing and system issues.
• Development of stave readout electronics
– Evaluate performance of SCTDAQ for multi-module tests
• Development of detectors
– BNL is pursing the 3 cm design
• Study of mechanical concepts for long staves – Bill Miller
–
–
–
–
Material
Geometry, cross-section
Cooling
Fabrication
• ABCD-next
– MRC definition?
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Complete Phase 1 Stave
• Fabricate bus cable
• Continue fabrication and test of remaining
hybrids and modules
• Assemble and test 2-3 staves for LBNL and
BNL, Hampton
• Costs within FY05 funding
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Alternate Powering
• Development of specs (LBNL)
• Add serial powering test to the Phase 1 stave
– New version of the bus cable (LBNL)
– Add power interface hybrid (LBNL, RAL)
– Use commercial components
• Investigate a “universal” configuration for serial and DC-DC
tests (LBNL)
• System issues – bypass, failure, noise (BNL)
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Readout System
• Need to understand how well current UK test
stand works for multi-module staves tests,
issue of concurrent operation
• Alternative is a simple pattern generation
approach similar to LBNL “Patt Board”
developed by MGS for CDF
• Engineering on this would be done at BNL and
is included in FY06 budget
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Detectors
• To go beyond the Phase 1 stave based upon
CDF Run2b surplus detectors required ATLAS
specific devices
• Candidate is the 3cm short strip design
• BNL will do a design and fabricate.
• For the outer stave the CDF devices may still
be useful – need to do inventory and
availability
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Mechanics
• 1m and 2m designs require new ME effort for design
and fabrication
– Laminates
– Boxes
– Extrusions
•
•
•
•
•
•
Low temperature operation
Materials
B.Miller effort – LBNL
Fixture studies – LBNL (FNAL connection)
BNL engineering
RAL engineering
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Conclusions/Actions
• Complete phase 1 stave
– Near term
• Develop serial powering modification to stave
– Summer 06
• ABCD-next effort
– Define interface aspect, MRC
• Continue mechanical studies
– Include monitored alignment concepts
• Develop test detectors for phase 2 stave
• Readout electronics study
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4.6°
R1000.000
R500.000
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