GridPix

Een Detector R & D project voor:

- Large TPC for ILC- GOSSIP & the ATLAS SCT Upgrade

Harry van der GraafNIKHEF, Amsterdam

Electronische Afdeling,Nikhef April 4, 2007

Time Projection Chamber (TPC): 2D/3D Drift ChamberThe Ultimate Wire (drift) Chamber

E-field(and B-field)

Wire Plane+Readout Pads

track ofchargedparticle

Wire plane

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)

wireavalanche

Cathode pads

GEMMicromegas

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 chipwithout X-ray convertor!

MediPix2 pixel sensorBrass spacer blockPrinted circuit boardAluminum base plate

Micromegas

Cathode (drift) plane

55Fe

Baseplate

Drift space: 15 mm

MediPix2 & Micromegas

Very strong E-field above (CMOS) MediPix!

He/Isobutane80/20Modified MediPix

δ-ray!

Efficiency fordetecting single electrons: < 95 %

Integrate GEM/Micromegas and pixel sensor:

InGrid‘GEM’ ‘Micromegas’

By ‘wafer post processing’

InGrid VS MicromegasInGrid VS Micromegas

MicromegasMicromegasElectroforming tech.Electroforming tech.

– Large areasLarge areas– Large pillar Large pillar Ø (250 µm)Ø (250 µm)– Hybrid detectorHybrid detector

Manual mountingManual mounting

InGridInGrid

Micro-electronic tech.Micro-electronic tech.– Wafer scale areasWafer scale areas– Minimum pillar Minimum pillar Ø (30 µm)Ø (30 µm)– Integrated detectorIntegrated detector

Compact / Mass producibleCompact / Mass producible

– All geometric parameters All geometric parameters accurately controlledaccurately controlled

Gap, Holes, Supporting structuresGap, Holes, Supporting structures

Processing InGridsProcessing InGrids

Strips Litho.

50 µm SU8 UV Exposure

0.8 µm Al Holes Litho.

Development

Suspended membrane 50 µm above the wafer

PrototypesPrototypes

19 different fields of 15 mm Ø19 different fields of 15 mm Ø2 bonding pads / fields2 bonding pads / fields

Square / Walls Square / PillarsSquare / Pillars

Hex / Pillars

Experimental SetupExperimental Setup

Cathode to HV

Grid to HV

Anode to ground

55Fe collimated source

Gas sealed chamber

Connectors to 10 MΩ resistors in series with

electrodes

Energy resolution in Argon Energy resolution in Argon IsoCIsoC44HH1010 80/20 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 DetectorThe ATLAS Detector

ATLAS Semiconductor Tracker (SCT)

Inner Tracker: record all tracksInner Tracker: record all tracksof charged particlesof charged particles

For instance: lifetime measurementFor instance: lifetime measurement

Heavy quark mesons….Heavy quark mesons….

Lifetime measured from secondary vertex Lifetime measured from secondary vertex cc~ 100 micron~ 100 micron

Take Lorentz boost into account Take Lorentz boost into account

KKD

DD slow*

m

Eγ

ALEPH event display

VertexingVertexingHigh spatial resolutionHigh spatial resolutionlow masslow masslow powerlow powerfastfast

Semiconductor pixel detectorSemiconductor pixel detectorVertex determinationVertex determinationFew pointsFew pointsaccuracy O(0.001-0.01 mm)accuracy O(0.001-0.01 mm)

Semiconductor (pixel, strip) Semiconductor (pixel, strip) detectorsdetectors

Depleted Si, 300 μm

(pixel) chip withpreamps, shapers,discriminators

Vbias = 150 V

electron-holepairs

ATLAS pixel: basic elementATLAS pixel: basic element

C-C support

sensor

Flex Hybrid

bumps

MCC Side view

not to scale

Wire-bonding FE’sWire-bonding MCC

FE chipFE chip

Flex module 2.xFlex module 2.x

The ATLAS Vertex Pixel DetectorThe ATLAS Vertex Pixel Detector

~2.0 m~2.0 m22 of sensitive of sensitive area with area with 0.8 0.8 10 1088 channelschannels

50 50 m m 400 400 mm silicon pixels (50 silicon pixels (50 m m 300 300 m in the B-m in the B-layer)layer)

Three barrel layers

Three disk layers

Barrel SCT unit

EndCap SCT unit

barrel SCTbarrel SCT

Two of the SCT barrel support structures

Barrel and EndCap SCT

Transition Radiation Tracker

e-

π-

X-ray quanta

Si (vertex) track detector GOSSIP

CMOS chip

Si depletion layer

Vbias

• Si strip detectors• Si pixel detectors• MAPs

Gas: 1 mm as detection medium99 % chance to have at least 1 e-

Gas amplification ~ 1000:

Single electron sensitive

All signals arrive within 16 ns

Cluster3

Cathode (drift) plane

Integrated Grid (InGrid)

Cluster2

Cluster1

Slimmed Silicon Readout chipInput pixel

1mm,100V

50um, 400V

50um

GOSSIP: Gas On Slimmed SIlicon Pixels

CMOS pixel array

MIP

InGrid

Drift gap: 1 mmMax drift time: 16 ns

MIP

CMOS chip‘slimmed’ to 30 μm

Cathode foil

Gas instead of SiPro:- 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

DischargesVonken

CMOS Chip protection against - discharges- sparks- HV breakdowns- too large signals

Emperical method:Try RPC technology

Amorph Si (segmented)

Silicon Protection: SiProt

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!!

MediPix+SiProt+InGridLevensduur: 12 hHe/Isobutane

A-Si not adequate? Then TwinGrid

Irradiation with 8 keV X-rays:Irradiation with 8 keV X-rays:

No No rate effectsrate effects up to anode up to anode current density of 0.2 current density of 0.2 μA / mm / mm22

very fast track counting very fast track counting possible!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

Very low (parasitic) capacitanceat the input (Cpar → 10 fF) .

Cpar = 10fF…50fF

Coaxial-like layout of the input-feedback interconnection.

Parasitic metal-to-metal fringe capacitances.

Input pad

Substrate

Cfb=1fF

Ground plane

Output

M1

M2

M3

M6

LM

Ground

GOSSIPO-1:

- test of preamp-shaper-discriminator for GOSSIP

- ‘MultiProjectWafer’ in 0.13 μm technology

GOSSIPO chipSubmitted December 2005.

- 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

- Threshold setting (6 x 60 e-) fine!- Effect of digital switching on pixel analog signal negligible

GOSSIPO (RO-FE) chip design

100 MHz clock close to analog circuit

Vthreshold = 350 e-

discriminator output

Maart – Juni 2006: Gossip-DAQ werkgroep

test ofpreamp-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!

GOSSIPO-2

3 x 2 mm2

Proposed FE architecture for data communication

avalancheinput pad

AmpShaDisc

700 MHzoscillator

start

stop

BXcounter

BX clock

40 MHz

memory 1BX-ID +Tdrift +Ttime-over-threshold

16 bits

DAQbus

valid BX

pixel-ID + Tdrift + TtimeOverthreshold

memory 2BX-ID +Tdrift +Ttime-over-threshold

16 bits

pixel

New mechanical concept(virtual) target: pixel B-layer @ SLHC

1. Inventarisation of all services to detector units2. 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

string: power, chip support, cooling

in 2030….

‘balloon’

‘laundry line’

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

laser

Interferometer

- rates up to 40 Gb/s- geen materiaal en dissipatie op chip- met 240 Gb/s: ‘all data to shore’: trigger possible

FE chip

- Ladder strings fixed to end cones- Integration of beam pipe, end cones & pixel vertex detector- 5 double layers seems feasible

Virtual goal: ATLAS pixel vertex

Stainless steel tube: - string- power- CO2 cooling

Gossip chip + InGriddrift gapcathode foil

ladder cross sectiondata lines (Cu/kapton)

casted aluminium

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