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

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

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!

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!

MediPix2 & Micromegas MediPix2 pixel sensor Brass spacer block 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!

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

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

InGrid VS Micromegas 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

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

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

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

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

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

The ATLAS Detector

ATLAS Semiconductor Tracker (SCT)

Lifetime measured from secondary vertex ct ~ 100 micron Inner Tracker: record all tracks of charged particles For instance: lifetime measurement Heavy quark mesons…. Lifetime measured from secondary vertex ct ~ 100 micron Take Lorentz boost into account

ALEPH event display

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

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

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

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) Three barrel layers Three disk layers

Barrel SCT unit EndCap SCT unit

barrel SCT Two of the SCT barrel support structures

Barrel and EndCap SCT

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

Si (vertex) track detector GOSSIP Cluster3 Cathode (drift) plane Integrated Grid (InGrid) Cluster2 Cluster1 Slimmed Silicon Readout chip Input pixel 1mm, 100V 50um, 400V 50um CMOS chip Si depletion layer Vbias 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

GOSSIP: Gas On Slimmed SIlicon Pixels 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

Gas instead of Si Pro: Con: 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

Discharges Vonken

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

- ‘Directe’ schade door heet plasma: afwezig 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!!

A-Si not adequate? Then TwinGrid

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

Nieuwe Pixel Chips voor GridPix/Gossip

GOSSIPO-1: test of preamp-shaper-discriminator for GOSSIP ‘MultiProjectWafer’ in 0.13 μm technology GOSSIPO chip Submitted December 2005. Input pad Substrate Cfb=1fF Ground plane Output M1 M2 M3 M6 LM Ground 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.

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

Maart – Juni 2006: Gossip-DAQ werkgroep

GOSSIPO-2 0.13 μm technology 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

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

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

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….

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

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

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

ladder cross section ladder side view ladder top view 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

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?)

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