Silicon strip staves and petals for the ATLAS Upgrade tracker of the HL-LHC
Sergio Díez Cornell, Berkeley Lab (USA),
On behalf of the ATLAS Upgrade strip tracker Collaboration
HSTD-8, Taipei, Taiwan, Dec 5th-8th, 2011
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 2
Motivation: ATLAS Phase II Upgrade (HL-LHC)
Numerous challenges for silicon sensors on ATLAS Phase-II Upgrade Higher granularity to keep same low occupancy Higher radiation tolerance to deal with increased radiation environment Novel powering solutions to power efficiently x7.5 more channels Maintain low cable count to keep detector performance Reduce cost per sensor to cover larger area (~ 200 m2)
Replacement of ATLAS Inner detector by an all-silicon tracker:
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Strips tracker: 3 layers of short strips (2.5 cm) staves2 layers of long strips (9.6 cm) staves10 disks of endcap petals
Si tracker (Utopia Layout)300 cm
75 cm
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 3
Stave concept layout and current prototypes
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1.2 m
12 cm
Ti coolant tube
Carbon honeycomb
Carbon fiber facing
Readout ICs
Si Strip sensor
Kapton flex hybrid Cu bus tape
Barrel strip stave (short strip version):
Designed to minimize material•Shortened cooling paths•Module glued to stave core with embedded pipes•No substrate or connectors, hybrids glued to sensors
Designed for large scale assembly•Simplified build procedure
All components testable independently Aimed to be low-cost
•Minimize specialist components
Short strip module:•1 n-in-p strip sensor with
4 x2.5cm strips•2 hybrids, each with 10
ABCN130 (256 ch) + 1 HCC/hybrid•Binary readout•Current prototypes:
ABCN250 (128 ch/chip) + BCCs
“Stavelets”:
Stave cross-section:
•Stave prototype with 4 modules per side•Single-sided stavelets (serial and DC-DC powered)
already built and under test at RAL[1]
High T conductivity foam
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 4
Stave/petal powering
LV: Two powering distributions under study for n hybrids, each with current I
HV: Parallel power limited by cable reuse and/or material limitations HV rad-hard switching for multiplexing under study recently (early stage)[2]
Current module and stave prototypes have proven to be a powerful test bench for the different powering options considered
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……Constantcurrent source
1 2 3 4 5 6 n-1 n
Constantvoltage source
1 2 3 4 5 6 n-1 n
……+-
Serial powering• Total current = I• Different GND levels per hybrid• AC coupling of data lines• Bypass protection required
DC-DC powering• Total current = n·(I/r*)• Switching system• Can be noisy• High mass*r = voltage conversion ratio
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 5
Other components of the stavelet prototypes
Basic Control Chip (BCC) boards for data I/O (1 per hybrid) AC coupled multi-drop system LVDS reception Generates 80 MHz DCLK and handles 160Mb/s
multiplexed data from each hybrid
Serial powering: Power Protection Board (PPB)[3]
Fast response and slow-control bypass of modules within an SP chain
Allows alternate SP shunt circuits Excellent performances demonstrated on SP stavelet SPP ASIC submitted Aug 2011
DC-DC powering: buck DC-DC converter Custom low-mass inductor and shield[4]
AMIS 4 ASIC: • Over current, over temperature, input under-
voltage, and soft start state machine for reliable start-up procedure[5]
New prototype circuits underway
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All hybrids onV = 22.7 V, I = 5.09 A
Slow control disables odd hybridsV = 12.7 V, I = 5.09 A
39x6 mm2
13x28 mm2
AMIS4
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 6
Stave modules production and tools
Scalability for large scale production even at prototyping stage Panelization of laminated hybrids
• Designed for machine placement of passives and solder reflow
• Tools developed for controlled gluing and wire bonding of ABCNs
• Conservative design rules for high yield and volume, and low cost
• Final hybrids testable on panels, ready for module assembly
Diverse tools developed for uniform gluing of hybrids to sensors• Numerous options investigated: glue spread on
sensor or hybrid backplane, different glue stencils,…
• Optimized glue thickness for best module performances: ~ 120 μm
Automated wire bonding of ASICs to sensor and hybrids to test frames
Fully testable modules, ready for stave assembly
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S. Díez Cornell, HSTD-8, Taipei (Taiwan) 7
Stave module testing
PCB test frames: cheap and flexible test benches for testing Different power configurations, G&S, added circuitry …
DAQ system for stave modules and stavelets: HSIO Generic DAQ board (ATCA form factor) with single (large)
Virtex-4 FPGA for data processing & connection to controller PC Interface board: connectors & buffers for connectivity to FEE Currently supports up to 64 streams (>64 streams with larger
FX100 FPGA in future) Upgraded sctdaq software
Allows standard 3ptGain, Response Curve, Noise Occupancy, DT Noise,… on ABCN-250 modules
Expected noise performances for parallel, serial, and DC-DC powered modules Similar ENC noise performances obtained at the different sites
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Berkeley, serial Freiburg, serial
Liverpool
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 8
Stave module construction and test
Numerous institutes involved in the construction and test of stave modules and stavelets[6]
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Up to 31 modules built so far(Nov 2011)
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 9
Proton irradiations of stave modules
Irradiated at CERN-PS 24 GeV proton beam scanned over
inclined modules Module biased, powered, and clocked
during irradiation Up to 2x1015 cm-2 reached Sensor and module behave as expected
• Noise increase consistent with shot noise expectations
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Slide borrowed from T. Affolder, TIPP2011, June 2011
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 10
Stavelets
Stave prototypes with 4 modules per side
Sensors directly glued to bus tape with “soft” glue for easy module replacement or removal
Key test bed for electrical testing Powering, protection, G&S, …
Single-sided serial and DC-DC powered stavelets built and tested so far SP stavelet tested with custom constant
current source (0-6A, OVP), excellent performances[7]
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Custom Cu bus tape
Power and PPBs
EOS board
EOSboard
BCCs
SP stavelet
DC-DC staveletPower and Buck DC-DC converters
Custom Cu bus tape BCCs
11
Stavelet bus tape layout
06/12/2011 S. Díez Cornell, HSTD-8, Taipei (Taiwan)
SP Trace Layer (Cu)
LVDS Clock/Command/Data & NTC
SP Current Return
HV
11100μm track/gap over 40cm (1.2m)
SP shield Layer (Al)
For DC-DC, the power section of the SP tape is cut off and replaced by a custom section
Slide borrowed from P. Phillips, TWEPP2011,Sept2011
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 12
Electrical tests on stavelets
ENC noise close to noise on individual modules for both stavelets Approximately ~ 20e higher in both cases SP stavelet: PPB and bypassing hybrids does not affect noise performances
Double Trigger Noise clean at 1 and 0.75fC with appropriate current routing Slightly better DT Noise performances at 0.5fC for DC-DC stavelet
Still work in progress[1]
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H0 H1 H2 H3 H4 H5 H6 H7
Column 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
ENC 661 623 628 675 650 636 697 760 687 646 640 666 680 661 624 656
DTN @1.0fC 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
DTN @0.75fC 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
DTN @0.5fC 130 40 1 58 3 1 255 1181 32 4 56 102 50 26 50 237
H0 H1 H2 H3 H4 H5 H6 H7
Column 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
dENC 8 1 27 26 11 2 17 26 -10 -9 28 31 -26 -23 -2 -2
DTN @1.0fC 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
DTN @0.75fC 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
DTN @0.5fC 0 1 6 36 18 5 12 38 12 2 4 9 0 0 0 4
Serially powered stavelet
DC-DC powered stavelet
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 13
Stave material estimates
Stave material estimates for 130 nm stave[8, 9]: Based on as-built stavelets
Titanium cooling tube: 2.2mm OD x 0.14mm wall Tapes contribution could be significantly reduced (~50%) by removing Al
screen + one glue layer: under investigation Sensor dominates module material (~ 63%) Power components will add 0.03 - 0.15 %X0, depending on power scheme
(first approximation: changes in bus tape not considered)
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%X0
Stave core 0.55%
Bus tapes 0.30%
Modules 1.07%
Module to stave adhesives 0.06%
TOTAL 1.98%
Stave core
Bus tapes
Modules
Module to stave adhesives
Modules54%
Stave core28%
Tapes15%
Adhesives3%
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 14
Endcap petals: Petalet program
The endcap petal follows closely the barrel stave design
First petal cores already been produced First endcap hybrids (ABCN-250 ASICs)
produced and tested Petalet prototype underway
Combines innermost radius sensors and region where petal splits in 2 sensor columns[10]
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“Petalet”Endcap hybrid
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 15
Conclusions
Stave program has shown significant progress Module prototypes built and shown to work after irradiation at higher
fluences than expected on the Si tracker Both LV powering architectures being studied in detail with stavelet
prototypes Up to 20 groups involved in the module/stave/petal construction and test Up to 31 modules and 2 single-sided stavelets, with both powering
schemes implemented, have been built and tested so far, more underway: Double-sided stavelets at RAL Stavelets at other construction sites Petalets
Full-size, next generation stave prototypes will be designed and built as soon as ABCN-130 ASIC is ready (6 months from now?)
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S. Díez Cornell, HSTD-8, Taipei (Taiwan) 16
Thank you! References
[1] P. Phillips, Stavelet status, ATLAS Upgrade week, CERN, Nov 2011
[2] D. Lynn, Possible Approaches to HV Distribution to Atlas Strip Staves, ATLAS Upgrade week, CERN, Nov 2011
[3] D. Lynn et al., Serial power protection for ATLAS silicon strip staves, NIM-A 633, pp. 51-60 (2011)
[4] G. Blanchott, DC-DC converters: gained experience, ATLAS Upgrade Week, CERN, Nov 2011
[5] S. Michelis, DC-DC powering ASICs, ATLAS Upgrade week, CERN, Nov 2011
[6] S. Wonsak, Stave module status, ATLAS Upgrade week, CERN, Nov 2011
[7] J. Matheson, Progress and advances in Serial Powering of silicon modules for the ATLAS Tracker Upgrade , JINST 6 C01019, 2010
[8] T. Jones, Strip stave radiation lengths, Local Support Working Group (LSWG) – Mechanics, Berkeley, Sept 2011
[9] A. Affolder, Material study , ATLAS Upgrade Week, Oxford, March 2011
[10] I. Gregor and C. Lacasta, The petalet, ATLAS Upgrade week, CERN, Nov 2011
Backup slides: Radiation hard n-in-p short strip sensors Thermo-mechanical stave demonstrator Short strip module Stavelets
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Radiation-hard short strip sensors
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Slide borrowed from T. Affolder, TIPP2011, June 2011
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 18
Thermo-mechanical stave demonstrator
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Slide borrowed from T. Affolder, TIPP2011, June 2011
S. Díez Cornell, HSTD-8, Taipei (Taiwan) 19
Short strip module
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S. Díez Cornell, HSTD-8, Taipei (Taiwan) 20
Stavelets
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Serial power:
DC-DC power:
