Silicon strip staves and petals for the ATLAS Upgrade tracker of the HL-LHC

1. 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

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: • Strips tracker: • 3 layers of short strips (2.5 cm) staves • 2 layers of long strips (9.6 cm) staves • 10 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 Barrel strip stave (short strip version): 1.2 m 12 cm • 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 Stave cross-section: Readout ICs Kapton flex hybrid Cu bus tape Ti coolant tube Carbon fiber facing High T conductivity foam Short strip module: “Stavelets”: Si Strip sensor Carbon honeycomb • Stave prototype with 4 modules per side • Single-sided stavelets (serial and DC-DC powered) already built and under test at RAL[1] • 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 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 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 Constant current source • DC-DC powering • Total current = n·(I/r*) • Switching system • Can be noisy • High mass • *r = voltage conversion ratio 1 2 3 4 5 6 n-1 n …… Constant voltage source + - …… 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 39x6 mm2 All hybrids on V = 22.7 V, I = 5.09 A Slow control disables odd hybrids V = 12.7 V, I = 5.09 A AMIS4 13x28 mm2 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 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 Liverpool Berkeley, serial Freiburg, serial 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] Up to 31 modulesbuilt 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 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] Power and PPBs SP stavelet EOS board Custom Cu bus tape BCCs Power and Buck DC-DC converters DC-DC stavelet EOS board Custom Cu bus tape BCCs S. Díez Cornell, HSTD-8, Taipei (Taiwan)

11. Stavelet bus tape layout SP shield Layer (Al) SP Trace Layer (Cu) HV SP Current Return LVDS Clock/Command/Data & NTC 100μm track/gap over 40cm (1.2m) 11 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] 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) Adhesives 3% Stave core 28% Modules 54% Tapes 15% 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] Endcap hybrid “Petalet” 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?) 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 S. Díez Cornell, HSTD-8, Taipei (Taiwan)

17. Radiation-hard short strip sensors Slide borrowed from T. Affolder, TIPP2011, June 2011 S. Díez Cornell, HSTD-8, Taipei (Taiwan)

18. Thermo-mechanical stave demonstrator Slide borrowed from T. Affolder, TIPP2011, June 2011 S. Díez Cornell, HSTD-8, Taipei (Taiwan)

19. Short strip module S. Díez Cornell, HSTD-8, Taipei (Taiwan)

20. Stavelets Serial power: DC-DC power: S. Díez Cornell, HSTD-8, Taipei (Taiwan)