GridPix Een Detector R & D project voor: Large TPC for ILC GOSSIP & the ATLAS SCT Upgrade

1. GridPix • Een Detector R & D project voor: • Large TPC for ILC • GOSSIP & the ATLAS SCT Upgrade Harry van der Graaf NIKHEF, Amsterdam Electronische Afdeling, Nikhef April 4, 2007

2. Time Projection Chamber (TPC): 2D/3D Drift Chamber The Ultimate Wire (drift) Chamber track of charged particle E-field (and B-field) Wire plane Wire Plane + Readout Pads Pad plane

3. Problem With wires: measure charge distribution over cathode pads: c.o.g. is a good measure for track position; With GEMs or Micromegas: narrow charge distribution (only electron movement) avalanche GEM wire Micromegas Cathode pads Solutions: - cover pads with resisitive layer - ‘Chevron’ pads - many small pads: pixels!

4. The MediPix2 pixel CMOS chip • 256 x 256 pixels • pixel pitch: 55 x 55 μm2 • Within each pixel: • preamp + shaper + discr • 14-bits counter • discr. thresholds • Developed by MediPix • Consortium, CERN We apply the ‘naked’ MediPix2 chip without X-ray convertor!

6. MediPix2 & Micromegas 55Fe Cathode (drift) plane Drift space: 15 mm Micromegas Baseplate MediPix2 pixel sensor Brass spacer block Printed circuit board Aluminum base plate Very strong E-field above (CMOS) MediPix!

8. He/Isobutane 80/20 Modified MediPix δ-ray! Efficiency for detecting single electrons: < 95 %

9. Integrate GEM/Micromegas and pixel sensor: InGrid ‘GEM’ ‘Micromegas’ By ‘wafer post processing’

10. Micromegas Electroforming tech. Large areas Large pillar Ø (250 µm) Hybrid detector Manual mounting InGrid Micro-electronic tech. Wafer scale areas Minimum pillar Ø (30 µm) Integrated detector Compact / Mass producible All geometric parameters accurately controlled Gap, Holes, Supporting structures InGrid VS Micromegas

11. Processing InGrids Strips Litho. 50 µm SU8 UV Exposure Holes Litho. 0.8 µm Al Suspended membrane 50 µm above the wafer Development

12. Prototypes Hex / Pillars 19 different fields of 15 mm Ø 2 bonding pads / fields Square / Pillars Square / Walls Square / Pillars

13. Experimental Setup 55Fe collimated source Gas sealed chamber Grid to HV Cathode to HV Anode to ground Connectors to 10 MΩ resistors in series with electrodes

14. Energy resolution in Argon IsoC4H10 80/20 • Observation of two lines: • Kα @ 5.9 keV • Kβ @ 6.4 keV • FWHM of the Kα distribution • 16.7 % • Gain fluctuations • < 5% Very good energy resolution: Very precise dimensions d < 0.1 μm

15. Other applications of GridPix: • μ-TPC • Transition Radiation Detectors • GOSSIP: tracker for intense radiation environment

16. The ATLAS Detector

17. ATLAS Semiconductor Tracker (SCT)

18. Inner Tracker: record all tracksof charged particlesFor instance: lifetime measurement • Heavy quark mesons…. • Lifetime measured from secondary vertex ct ~ 100 micron • Take Lorentz boost into account

19. ALEPH event display

20. Vertexing • High spatial resolution • low mass • low power • fast  Semiconductor pixel detector • Vertex determination • Few points • accuracy O(0.001-0.01 mm)

21. Semiconductor (pixel, strip) detectors Depleted Si, 300 μm Vbias = 150 V electron-hole pairs (pixel) chip with preamps, shapers, discriminators

22. Flex Hybrid Wire-bonding MCC Wire-bonding FE’s MCC Side view not to scale sensor bumps FE chip FE chip C-C support Flex module 2.x ATLAS pixel: basic element

23. Three disk layers Three barrel layers The ATLAS Vertex Pixel Detector • ~2.0 m2 of sensitive area with 0.8  108 channels • 50 m  400 m silicon pixels (50 m  300 m in the B-layer)

24. Barrel SCT unit EndCap SCT unit

25. barrel SCT Two of the SCT barrel support structures

26. Barrel and EndCap SCT

27. X-ray quanta e- π- Transition Radiation Tracker

28. Cathode (drift) plane Si depletion layer Cluster1 Cluster2 1mm, 100V Vbias Cluster3 Integrated Grid (InGrid) CMOS chip 50um, 400V Slimmed Silicon Readout chip Input pixel 50um Si (vertex) track detector GOSSIP Gas: 1 mm as detection medium 99 % chance to have at least 1 e- Gas amplification ~ 1000: Single electron sensitive All signals arrive within 16 ns • Si strip detectors • Si pixel detectors • MAPs

29. MIP MIP InGrid Cathode foil CMOS pixel array CMOS chip ‘slimmed’ to 30 μm Drift gap: 1 mm Max drift time: 16 ns GOSSIP: Gas On Slimmed SIlicon Pixels

30. Gas instead of Si • Pro: • no radiation damage in sensor: gas is exchanged • modest pixel (analog) input circuitry: low power, little space • no bias current: simple input circuit • CMOS pixel chip main task: data storage & communication (rad hard) • low detector material budget: 0.06 % radiation length/layer • typical: Si foil. New mechanical concepts: • self-supporting pressurized co-centric balloons; ‘laundry line’ • low power dissipation : little FE power (2 μW/pixel); no bias dissipation • operates at room temperature (but other temperatures are OK) • less sensitive for neutron and X-ray background • 3D track info per layer if drift time is measured • Con: • Gaseous chamber: discharges (sparks): destroy CMOS chip • gas-filled proportional chamber: ‘chamber ageing’ • Needs gas flow • Parallax error: 1 ns drift time measurement may be required

31. Discharges Vonken

32. CMOS Chip protection against - discharges - sparks - HV breakdowns - too large signals Silicon Protection: SiProt Amorph Si (segmented) Emperical method: Try RPC technology

33. MediPix+SiProt+InGrid Levensduur: 12 h He/Isobutane • Met 3 μm SiProt: • - ‘Directe’ schade door heet plasma: afwezig • te groot ladingssignaal voor pixel electronica •  • Dikkere SiProt laag (20, 30 , 40, 50 μm ! ) • Protectie circuit in pixel • SiProt aan onderkant van InGrid • !!Als dikkere SiProt niet werkt: • MPW test (Gossipo-3) • 600 kE nodig voor nieuwe full-scale pixel chip!!

34. A-Si not adequate? Then TwinGrid

35. Irradiation with 8 keV X-rays:No rate effects up to anode current density of 0.2 μA / mm2 very fast track counting possible! After 0.3 Coulomb/mm2:  (eq. 3.7 x 1016 MIPs/cm2 !!) deposit of carbon polymer on anode is clearly visible. Micromegas is clean (!?) Little deposit on cathode, and…… Chamber still worked! Ageing

36. Nieuwe Pixel Chips voor GridPix/Gossip

37. Input pad LM Ground plane M6 Ground Output M3 Cfb=1fF M2 M1 Substrate • GOSSIPO-1: • test of preamp-shaper-discriminator for GOSSIP • ‘MultiProjectWafer’ in 0.13 μm technology GOSSIPO chip Submitted December 2005. Very low (parasitic) capacitance at the input (Cpar → 10 fF). Cpar = 10fF…50fF Parasitic metal-to-metal fringe capacitances. Coaxial-like layout of the input-feedback interconnection.

38. GOSSIPO (RO-FE) chip design • - match extreme small source capacity: 10 fF • peaking time: 40 ns • noise (expected: 60 e- input eq.) • power: 2 μW/pixel (!) • Triple Well technology: separation of analog and digital ground 100 MHz clock close to analog circuit • Threshold setting (6 x 60 e-) fine! • Effect of digital switching on pixel • analog signal negligible Vthreshold = 350 e- discriminator output

39. Maart – Juni 2006: Gossip-DAQ werkgroep

40. GOSSIPO-2 • test of • preamp-shaper-discriminator • and • 700 MHz TDC per pixel • 0.13 μm technology • containing 16 x 16 pixels • Submission Nov 29, 2006 • Can be used for GOSSIP demo! 3 x 2 mm2

41. Proposed FE architecture for data communication pixel 700 MHz oscillator avalanche input pad start AmpShaDisc BX clock stop 40 MHz BXcounter memory 1 BX-ID +Tdrift +Ttime-over-threshold 16 bits memory 2 BX-ID +Tdrift +Ttime-over-threshold 16 bits valid BX DAQ bus pixel-ID + Tdrift + TtimeOverthreshold

42. New mechanical concept • (virtual) target: pixel B-layer @ SLHC • Inventarisation of all services to detector units • Integration of services, detectors and support mechanics • services: • cooling • power • data communication • gas

43. New mechanics + cooling concepts for Gossip • As little as possible material • detector consists of foil! • less power required ( less cooling) w.r.t. Si ‘laundry line’ ‘balloon’ string: power, chip support, cooling in 2030….

44. Minimum Material Budget (% rad length) Z = 0 mm Z = +/-600 mm Gossip detector (50 μm Si) 0.06 0.06 Cooling (stainless steel tube) 0.001 0.001 Power (max 0.28 mm aluminium) 0.0 0.3 Data transfer (max 1.7 mm kapton) 0.0 0.6 total 0.06 1 angle correction x √2 0.09 x 2 x √2 3

45. New concepts for optical fiber data transfer FE chip laser Interferometer • rates up to 40 Gb/s • geen materiaal en dissipatie op chip • met 240 Gb/s: ‘all data to shore’: trigger possible

46. Virtual goal: ATLAS pixel vertex • - Ladder strings fixed to end cones • Integration of beam pipe, end cones & pixel vertex detector • 5 double layers seems feasible

47. data lines (Cu/kapton) ladder cross section casted aluminium Gossip chip + InGrid drift gap cathode foil Stainless steel tube: - string - power - CO2 cooling ladder side view ladder top view

48. First practical GOSSIP • with • CMS Vertex Pixel FE chip: PSI 46 (+ ATLAS FE pixel chip?) • apply A-Si protection layer • apply InGrid • mount Gossips on pcb: ‘ beam telescope’ • Testbeam end 2006 Nijmegen, NIKHEF (,PSI?)

49. Gossip projects at NIKHEF/Univ. Twente/Saclay/CERN • Discharge protection • InGrid/TwinGrid/TripleGrid • Construction of detector: MediPix2 + SiProt + InGrid NewNext-1! • Construction of detector: TimePix + SiProt + InGrid NewNext-1 • - Gossipo chip developments • Development of ‘beam telescope’ Gossip demo • Vertex track simulations: signal development, DAQ data streams • - Study of ‘services’ required for Gossip/SLHC: • assume dose rate of 12 tracks/(cm2 . 25 ns) • definition of cooling; • definition of data transfer connection; • definition of power lines • - Ladder prototype: thermal modeling; Design of SS/Alu multifunctional string; • test (mech + thermal) of mechanical model • CO2 cooling: ATLAS/NIKHEF project • Ageing studies