CMS Tracker Upgrade for SLHC Duccio Abbaneo, CERN On behalf of CMS Tracker Collabora@on 1 Outline •  Perspec@ve: Experience with CMS Tracker •  Mo@va@ons for upgrade •  “Phase I” (Pixels only) –  Covered in other talks •  “Phase II” (Full Tracker) –  Main R&D ac@vi@es •  Mo@va@ons, goals, status, perspec@ves 2 CMS = Compact Muon Solenoid HCAL
Muon
chambers
Tracker
ECAL
4T solenoid
Total weight: 12,500 t
Overall diameter: 15 m
First opera@on during 2008 Overall length 21.6 m
pp collisions at 7 (or more) TeV CM energy in 2009/10 Magnetic field 4 T
3 Current Tracker system TOB
TEC
TIB
PD
BPIX
TID
FPIX
4 Current Tracker system Strips 10‐20cm × 180μm × 500μm Occup ~ 1% 55< r (cm)<115 TOB
TEC
Strips 10cm × 80μm × 320μm Occup ~ 2% 22< r (cm)<55 TIB
TID
(BPIX) Pixels 100μm × 150μm × 280μm PD
‐4 Occup ~ 10 BPIX FPIX
R = 4, 7, 11 cm in BPIX, 5‐16 cm FPIX 5 Current Tracker system r = 115 cm 300 KHz/cm2, 2×1013/cm2, 1.8kGy TOB
TEC
r = 22 cm 1 MHz/cm2, 2×1014/cm2, 70kGy TIB
TID
r = 4 cm PD
BPIX
FPIX
2, 3×10
15/cm2, 800kGy 100 MHz/cm
fluxes at 1034/cm2/s fluences/doses at 500i‐1 6 Commissioning (2008) •  6 months to connect and commission 10°C –  98% working •  3 months opera@on –  1 month CMS global running cosmics –  B= 3.8T 7 Performance (2008) •  Tracker opera@ons very stable and successful Strips: 8M tracks 98% working S/N >25 Efficiency per layer: >99% Resolu@on 14‐40μm in r‐Φ (depending on angle and strip pitch) Pixels: 85k tracks Barrel 99% working Endcap 94% (6% fixed in 2009) Efficiency >95% per layer (limited by random arrival @me of cosmics) Resolu@on: 20μm in r‐Φ and 30μm in z 8 Performance (2008) •  Tracker opera@ons very stable and successful Strips: 8M tracks 98% working S/N >25 Efficiency per layer: >99% Resolu@on 14‐40μm in r‐Φ (depending on angle and strip pitch) Pixels: 85k tracks Barrel 99% working Endcap 94% (6% fixed in 2009) Efficiency >95% per layer (limited by random arrival @me of cosmics) Ready for beam! Resolu@on: 20μm in r‐Φ and 30μm in z 9 Mo@va@ons for upgrade: LHC Luminosity profile •  ‘Phase I’ –  luminosity to 3×1034cm‐2s‐1 •  ‘Phase II’ –  Super LHC –  1035cm‐2s‐1 Linac4 + IR upgrade phase 1 New injectors + IR upgrade phase 2 Collima=on phase 2 •  Expect schedule to evolve with experience Ref: L. Evans, SLHC‐PP 27‐2‐09 P
I
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e
has
10 Phase I: L=3×1034cm2s‐1 Pixels Upgrade (Coordinators R. Horisberger, S. Kwan) •  Present pixel detector nominally expected to withstand 6×1014 cm‐2 •  Fluence expected for 500 i‐1: 3×1015 cm‐2 in layer 1 •  Nominally need to replace layer 1 every two years! •  Detector designed for easy removal •  Successfully demonstrated this year 11 CMS Pixel detector handling •  Flexibility: Pixel system removable/
installable in few days •  Removal foreseen for –  Bakeout of beam pipe –  Maintenance/
upgrade •  FPIX successfully removed, maintained, reinserted this year Note: Physical envelope, posi@on of beam‐pipe supports and rails all fixed 12 Pixel upgrade New requirement from current LHC luminosity plan: –  Minimize dead @me for luminosi@es above 1034, due to size of buffers in FE electronics New requirements from ambi@on of physicists: –  Reduce substan@ally material in the Tracking volume –  Add one more barrel layer and one more forward disk Expect large benefits for tracking performance, especially at high luminosity Constraint: –  Re‐use exis@ng services (from first patch‐panel to back‐end) Originally planned “replacement” now become a fairly major upgrade R&D ac@vi@es on –  Cooling –  Electronics (both front‐end and system aspects) –  Mechanics Covered in dedicated talks 13 Phase II: L=1035cm2s‐1 Full Tracker Upgrade (Coordinators: G‐M Bilei, G Hall, R Horisberger) •  Hundreds of collisions per bunch crossing •  ×10 radia@on flux Straigh<orward requirements: •  Higher granularity Most of the a@en=on to the outer part, for the =me being –  maintain occupancy at % level •  Greater rad‐resistance 14 One more requirement Ref: J. Inst CMS paper, 2008 •  Want to maintain and possibly improve tracking performance •  Current Tracker has a lot of material –  modules, power cables, cooling, support structures –  Par@cularly between barrel and endcaps Minimize material in the tracking volume 15 Services constraint: CMS central detectors •  As for Phase I pixels, must re‐
use services: –  Power cabling –  Op@cal cabling –  Cooling pipes •  Tracker cables and pipes buried under ECAL/HCAL services 16 e.g. Power cabling •  From 32 TK patch‐panels to 33 power racks distributed on 6 balconies •  This rou@ng is fixed! •  Similar issues for fibres and pipes An impressive puzzle to make best use of exis@ng power cabling plant. 17 Requirements + constraints ⇒ R&Ds •  Higher fluence requires more rad tolerant sensor material 1.  R&D on silicon sensors: material and design -  Choice of thinner sensors also helps reducing mass in the Tracking volume •  Higher par@cle density requires higher granularity •  New genera@on electronics: lower power / channel, but mostly thanks to lower supply voltage •  Power dissipated in cables cannot increase. Current in cables cannot increase •  Substan@al increase in n of channels requires bringing in power at higher voltage 2. R&D on novel powering schemes -  Also helps reducing mass in the Tracking volume by reducing X‐sec@on of power lines 18 R&Ds (cont’d) •  Power dissipated in the detector may be larger •  Opera@ng temperature for sensors will be most likely significantly lower (from ‐10°C to ‐20°C, current best guess) •  Coolant temperature cannot be lowered (hard limit at ‐30°C from cooling channels insula@on) •  Coolant flow in the detector cannot be significantly increased (size and available number of cooling pipes fixed) 3. R&D on more efficient cooling methods -  Also helps reducing mass in the Tracking volume by reducing mass of coolant, pipes and heat exchangers 19 New Requirement: Tracker input to Level‐1 trigger µ, e and jet rates exceed 100kHz at SLHC •  Need to maintain L1 at 100kHz •  Will need Tracker data but cannot deliver all Tracker data at 40MHz •  With on‐detector PT cut can reduce data rates   PT > 1÷2GeV/c to obtain ≈ 20× reduc@on in inner strip layers •  Expect also to require poin@ng to primary z vertex to recover isola@on criteria 4. R&D on “PT modules” L = 1034 muon L1 trigger rate -  Possibly heavy and power hungry 20 R&Ds (cont’d) •  Development of PT modules highly non‐trivial; difficult to predict final outcome in terms of mass and power consump@on •  Trigger informa@on from all Tracker layers may not be necessary 5. R&D on new “readout modules” -  Higher granularity than present Tracker (shorter strips); exploit new electronics and more advanced technologies for hybrids -  Eventually op@mize N of PT layers vs N of readout layers to maximize performance •  Large data volume, mostly because of trigger 6. R&D on data links -  Need high bandwidth with moderate power and low mass 21 Sensor R&D (1) Several ac@vi@es ongoing or planned Extensive project started with HPK •
Wafer contains –  mul@geometry •
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Strip structures Long pixel structures Pixel with p‐stop and p‐spray technology Dedicated test structures Standard mini sensors Dedicated structures to test channel rou@ng •
with diverse pitches, widths
p‐in‐n‐FZ (100µm, 200µm, 300µm) p‐in‐n‐MCz (200µm) n‐in‐p‐FZ (100µm, 200µm, 300µm) n‐in‐p‐MCz (200µm) p‐in‐n EPI (75µm, 100µm) n‐in‐p EPI (75µm, 100µm) n‐in‐p with both p‐spray and p‐stop Some n‐in‐p and p‐in‐n with an addi@onal double metal layer for rou@ng evalua@on 12 strip regions with diverse pitches, widths
12 strixel regions with diverse pitches, , widths, lengths, biasing
with diverse pitches, , widths, lengths, biasing
E.g. to avoid pitch adapters •  20 flavours × 6 wafers each –
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12 strip regions 12 strixel regions 22 Sensor R&D (2) •  Exhaus@ve inves@ga@on of geometrical and technological phase space •  Mixed radia@on, and radia@on to different fluences planned –  CCE and strip characteriza@on –  Channel isola@on and breakdown •  Expect to iden@fy technology and geometry for CMS Tracker sensors, at least for radii above 10‐20 cm •  First few cm of radial range may require radically different op@ons –  Some studies already ongoing 23 Power R&D (1) •  Powering scheme chosen based on DC‐DC conversion •  The inductor‐based “buck“ converter can provide currents of several Amps •  Other converter types (switched capacitors) can be used in addi@on (2‐step scheme) Switching noise
Ferrites saturate for B > ~2T
⇒ air-core inductor needed
Vin ≈ 12V
⇒  HV-tolerant
semi-conductor
technology needed
→ radiation-hardness
bulky
radiates noise Efficiency
Material budget
Simplified scheme of a buck converter
(feedback control loop not shown)
Space constraints
24 Power R&D (2)  ASICs development
•  Due to high input voltage of O(10V) standard CMOS processes cannot be used
•  Need high-voltage compatible radiation-hard technology
•  Second buck converter prototype in AMIS technology “AMIS2“ under test
-  Known to be not sufficiently rad-hard
•  First buck prototype in rad-hard SGB25V technology from IHP (Frankfurt/Oder)
expected in ~3 weeks
•  Switched capacitor block in 130nm for on-chip use by ATLAS: layout ~ finished
 System aspects
•  Noise issues
-  Switching devices → voltage ripple → conduc@ve noise -  Air‐core inductor → radia@ve noise •  Possible solu@ons explored -  Op@miza@on of EMI of buck converter PCBs -  Understanding coupling mechanisms and op@miza@on of module design -  Improvement of Power Supply Rejec@on Ra@o (PSRR) of FE‐Electronics •  Integra@on issues -  Mass and volume; analysis ongoing 25 Cooling R&D (1)   Two‐phase CO2 cooling chosen as baseline to replace liquid C6F14   Choice based on –  Posi@ve experience of NIKHEF with AMS and LHCb VELO –  Excellent thermodynamic proper@es for micro‐channels •
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Low dT/dP Low mass Low liquid/vapour density ra@o Low viscosity High latent heat High heat transfer coefficient   Main advantages for the CMS Tracker –
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High heat transfer coefficient ⇒ smaller heat‐exchanger contacts High latent heat ⇒ more heat load per single channel, smaller pipes, less manifolding Substan@ally cheaper (≈ 1 CHF/kg) than C6F14 (≈ 100 CHF/kg) Not harmful for the environment (e.g. during tests it can be vented to the atmosphere)   Substan@al differences wrt to LHCb 
Size of the system, pipe layout, acceptable pressure range, opera@ng temperature, power load…   A CO2 system needs to be designed and tested for CMS specifically 26 Cooling R&D (2) •  About 10 labs contribu@ng to R&D, addressing different aspects in parallel –  System aspects in a large re‐circula@ng system –  Design and test program for the construc@on of a full –scale system –  Performance studies for op@miza@on of working parameters (T, P, internal pipes dimensions and shape) –  Analysis of constraints from outer pipes and safety aspects •  No major problem found so far •  Concentra@ng on pixel upgrade, with a long‐term view on full upgrade 27 CMS is going along the NIKHEF Mantra CO2 is good for cooling CO2 is good for ATLAS …and CMS! CO2 is good for environment CO2 is good for everybody A.P. Colijn, NIKHEF Workshop on CO2 cooling, July ‘09 28 PT modules R&D: “Stacked layers”   Op@mal op@on for radial range 20÷40 cm, in barrel configura@on   Provides (some) z informa@on at L1 Pass R -  OpLon opLmized for larger radii also considered (strips) -  Not providing z informaLon at L1 -  Not covered in this presentaLon •  Closely stacked layers ≈1mm separa@on •  PT cut set by angle of track in stack; compare locally pa•ern of hits in stack •  (Off detector) Correlate track stubs from different stacked layers •  Z‐coordinate from ≈2mm pixel length •  Difficult to minimize power and mass   Design effort started, using commercially available technologies   Some more advanced op@ons also explored Upper Sensor ≈1mm ≈100μm Fail φ Lower Sensor 29 A possible PT module design data out control in 26mm concentrator φ 80mm z sensor ROC R‐φ sec@on R φ assembler custom part or integrated into PCB PCB ~2mm PCB 30 6*(7.2 + .8) mm PT module: another design •  “Ver@cal” data transmission through substrate •  Correla@on logic implemented at pixel level •  Dimension limited by substrate technology z 3*16 mm + 10 mm φ TFEA R TFEA TFEA Sensor … Substrate … z low profile wire bonds 7.2 mm Sensor 250 μm 150 μm 100 μm 800 μm 100 μm 150 μm 250 μm other service func@ons R 16 mm φ Read Out 31 PT module – a variant •  Same as before with different interconnec@on technology •  Double bump assembly with through vias in the chip TFEA … … 8.0 mm Substrate Sensor 250 μm C4 100 μm ASIC 100 μm C4 100 μm Substrate 700 μm C4 100 μm ASIC 100 μm C4 100 μm Sensor 250 μm Through Via AUX 16 mm ROA 32 PT module – a less conven@onal approach •  Feasibility and possible advantages of 3‐d electronics also being explored •  VICTR project at FNAL ‐ Ver@cally Integrated CMS TRigger Chip Sensor Interposer Bump Bond module Sensor 33 Readout module R&D TCS I/O PLL shielded micro‐twisted pairs I/O DC‐DC out 2.5V 2 x 4‐MUX + LCDS driver each output 160Mbit/s DC‐DC I/O made via connector to strain relieved cable pigtail Sensor HV 8x CBC 2x 128ch wire bonded 40Mbit/s out each TCS I/O PLL DCU shielded micro‐twisted pairs I/O DC‐DC out 2.5V Sensor HV Sensor with 2x 5 cm strips 2x 1024 @95 μm pitch integrated pitch adaptor 2 x 4‐MUX + LCDS driver each output 160Mbit/s DC‐DC I/O made via connector to strain relieved cable pigtail 8x CBC 2x 128ch wire bonded 40Mbit/s out each CF frame with fixa@on points and thermal contacts to rod cooling DCU Sensor with 4x2.5cm strips 2x 1024 @95μm pitch integrated pitch adaptor CF frame with fixa@on points and thermal contacts to rod cooling 34 Readout module R&D •
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Developing module concept and integra@on Binary unsparsified readout proposed Lightweight hybrid and minimalis@c frame Integra@on with support structure, cooling, power •  3‐d modelling and thermal analysis ongoing z φ R Hybrid Frame Sensor z R Power φ 35 Data links R&D •
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Integrated bi‐direc@onal data link for data, clock and trigger, slow control Total bandwidth 5 Gb/s Chipset and optoelectronics packaging under development/tes@ng Development of front‐end interface started Expect full link prototype available next year •  First evalua@ons very posi@ve for readout layers •  May require further development for PT layers (both performance and integra@on aspects) 36 Example of layout under study •  “Hybrid” layout •  2× barrel ‘PT layers’ –  R1≈22cm, R2≈35cm –  Stacked modules –  100μm x 2mm pixels •  ‘Outer Tracker’ –  Barrel plus endcap –  Strips 2.5cm, 5cm, ≈100μm pitch Assump>ons for power   Readout: 0.5 mW / channel   PT: 0.1 mW / channel   2 W / GBT op=cal channel 37 Modelling studies: Outer Tracker •  19M strips –  (85m2, 12kW, 1700 optolinks) •  Lightweight •  Can be done with only two module flavours <radia=on length> [0<h<2.4]: 12 % <interac=on length> [0<h<2.4]: 3.8 % 38 Modelling studies: PT layers (‘hybrid’ layout) •  115M pixels in PT layers –  (27m2, 24kW, 6300 optolinks) •  (As expected) PT layers dominate power and material budget [Rather conserva@ve assump@ons ‐ to be revised with R&D progress] <radia=on length> [0<h<2.4]: 52 % <interac=on length> [0<h<2.4]: 15 % 39 Tracking (+ triggering) simula@on •  Large effort in developing SLHC tracking simula@ons •  Started from tools hard‐
wired to current CMS TK geometry •  Now working with similar geometries to layout modelling studies More work to be done on material (supports, services) 40 Conclusions (1) •  Current tracker performance very encouraging •  CMS Tracker upgrade is again a large and complex project –  Split in two phases driven by planned increase in LHC luminosity •  Phase I a‡er ≈4 years running: upgrade pixel system •  Phase II a‡er ≈10 years running: full tracker upgrade –
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Contribute to L1 trigger Withstand 10 × LHC luminosity and fluences Maintain, and possibly improve, current tracking performance Gain from lessons learned to op@mise layout, module design, engineering 41 Conclusions (2) •  Many ac@ve areas of R&D for phase II upgrade –  Simula@ons (Tracking, Triggering, Layout) –  In the Lab (Sensors, Modules, Electronics, Powering, Cooling, Mechanics, Radia@on effects, Test systems, Monitoring…..) –  So far focussing mostly on the outer part •  Providing data for the L1 trigger stands out as a formidable challenge •  The development of PT modules and layers is a key point for the future detector •  For more info: h•p://cmsdoc.cern.ch/Tracker/Tracker2005/TKSLHC/index.html 42