GOSSIPa new vertex detector for ATLAS

Harry van der GraafNIKHEF, Amsterdam

Univ. of Bonn, Nov 23, 2006

New gaseous detectors:the application of pixel sensors as direct anode

NIKHEF Auke-Pieter ColijnAlessandro FornainiHarry van der GraafPeter KluitJan TimmermansJan VisschersMaximilien

Chefdeville

Saclay CEA DAPNIA Paul ColasYannis GiomatarisArnaud Giganon

Univ. Twente/Mesa+ Jurriaan Schmitz

CERN/Medipix Constm Eric HeijneXavie LlopartMichael CampbellThanks to:

Wim GotinkJoop RovenkampArnaud Giganon

Harry van der Graaf, NIKHEF, Amsterdam

University of Bonn Oct 14, 2004

GOSSIP: Gas On Slimmed SIlicon Pixels

CMOS pixel array

MIP

InGrid

Drift gap: 1 mmMax. drift time: 16 ns

MIP

CMOS pixel chip‘slimmed’ to 30 μm

Cathode foil

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

April 2004 Micromegas + MediPix 2 NIKHEF/Saclay/Univ. Twente:

MediPix2 pixel sensorBrass spacer blockPrinted circuit boardAluminum base plate

Micromegas

Cathode (drift) plane

55Fe

Baseplate

Drift space: 15 mm

MIPs

No source, 1sNo source, 1s5555Fe, 1sFe, 1s

He/Isobutane80/20Modified MediPix

δ-ray!14 mm

Integrate Micromegas and pixel sensor:

InGrid

‘wafer post processing’by

Univ. of Twente, MESA+’“there is plenty of room at the top”

PrototypesPrototypes

hidden pillars!

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

May 2005

A-Si not adequate? Then TwinGrid

Gas instead of Si Pro

Low mass detector!

- low power: 2 μW/pixel (analog), 0.6 μW/pixel (digital) Total 2.6 μW/pixel 0.1 W/cm2 due to:

- extremely low source capacitance (10 fF)- fast & arbitrary large charge signals- no bias current

little material required for power & cooling

- Thinning (Slimming) of CMOS pixel chip to 50 μm

detection layer: only 0.06 % radiation length

new vertex detector: 5 – 10 layers instead of 3

Input pad

Substrate

Cfb=1fF

Ground plane

Output

M1

M2

M3

M6

LM

Ground

Gas instead of Si Pro

- a GOSSIP detector measures a track segment instead of a point-in-space:

- single-electron sensitive (eff > 95 %)- ~ 10 e- along 1 mm track length- spatial resolution: 50 μm / √10 = 15 μm

14 mm3

- radiation hardness- gas is flushed- CMOS chip (130, 90, 45 nm technology): sufficiently radiation hard for SLHC

- very low sensitivity for neutrons, X-rays and gammas- ‘simple’ CMOS chip:

- modest (small area) analog input circuits- no bias current: simpeler input circuit- pixel area available for data storage & communication

- Cheap

Gas instead of Si Con

- GOSSIP has 1 mm detection layer:

- parallax error: elimination requires drift time measurement- with single-electron measurement: track segment data per layer!

- Gas-filled detector:

- chamber ageing (deposit on electrodes)- discharges (sparks, too large signals) ruin CMOS chip

showstoppers !

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

Emperical method:Try RPC principle

Amorph Si (segmented)

Silicon Protection: SiProt

- RPC principle: reduction of local E-field- Avalanche charge: electrostatic induction towards input pad- Specific resistance: - high enough to ‘block’ avalanche charge

- low enough to flow signal current- layer thickness 4 μm, Rvol > 0.2 – 100 GΩ/cm

TechnologyA-Si deposit: standard wafer post processing, but wafers may get too hot

Univ. of Neuchatel/IMT/P. Jarron (CERN) uses this for integrated X-ray sensor/convertor on MediPix 2

--- -

Test: put Thorium in gas: Radon α-decays: - large (proportional) signals

- Discharges: like short circuits

plasmaA-Si

The SiProt chamberThe SiProt chamberLow temperature deposition (< 250Low temperature deposition (< 250°°C) of a C) of a 4 4 μμm thick a-Sim thick a-Si layer of layer of 10101111 ΩΩ.cm .cm resistivityresistivity

Experimental setup:Experimental setup:– 1 bare anode and 1 a-Si covered anode with Micromegas on top1 bare anode and 1 a-Si covered anode with Micromegas on top– Gain curve with an Iron 55 sourceGain curve with an Iron 55 source– Induce discharges by means of 5 MeV alphas from Th source Induce discharges by means of 5 MeV alphas from Th source in gasin gas– Record grid signalsRecord grid signals

Micromegas grids

prot. anode

un-prot. anode

Aluminum

a-Si

To digital scope or pre-amplifier

SiProt chamberTh container

Digitalscope

cathode

Discharge Discharge Signals studySignals study

No preamplifierNo preamplifier

Ar 20 % iCAr 20 % iC44HH1010

Signals from ~ 5 MeV alphasSignals from ~ 5 MeV alphasFast digital scopeFast digital scope

UN

UN

UN

PROT

PROT

PROT

- no hot plasma on pixel input pads- reduced charge & current

Looks like it works!Next: try on Medipixchips

Discharge signals:short-circuit betweengrid and anodedue to plasma

55Fesource

Look at the pulses from a (calibrated) preamplifier (low grid voltage)

Look at the current flowing through the power supply (high grid voltage)

No sparks up to 570 V on the grid !

Next step: SiProt (and InGrid) on Medipix, TimePix

from current

from pulse height

Gain in Ar 20 iso

1.00E+02

1.00E+03

1.00E+04

1.00E+05

1.00E+06

1.00E+07

1.00E+08

1.00E+09

300 400 500 600

HV (V)

Ga

in

Unprotected

Protected (currentmode)

Protected (pulsemode)

Gain measurement

AgeingAgeingAgeing of a GOSSIP detector versus wire chambers:

- Ratio of anode surface/chamber volume:- thin wire surface versus anode plane (~20x)

- Low gas gain (1 k) due to fast signal and low source capacity (~20x)

total factor: 400 x

So: application as GOSSIP vertex detector in Super LHC

1016 MIP/cm2

seems feasible First try

Ageing: remember the MSGCs….

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!

Ongoing projects

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

Cpar = 10fF…50fF

Coaxial-like layout of the input interconnection.Parasitic metal-to-metal

fringe capacitances.

Cfb

Rfb

Cpar Iin(t)

Qin

Output

Open loop voltage gain of the OPAMP

A

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

Triple well layout:

isolation of digitalandanalog sections

Guard rings GNDGND_ana

VDD_ana

P-type substrateP-well

N-well

Analog P-type FET area

Analog N-type FET area

Digital N-type FET area

substrate current

GNDGND_ana

VDD_ana

- match extreme small source capacity: 15 fF- peaking time: 40 ns- noise (expected: 60 e- input eq.)- power: 2 μW/pixel (!)

MultiProject Wafer:

Vladimir Gromov/NIKHEF CERN Micro-electronics group

- Input noise eq. reached- No effect of digital switching within pixel

GOSSIPO chipSubmitted December 2005.

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

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

‘laundry line’

- Ladder strings fixed to end cones- Integration of beam pipe, end cones & pixel vertex detector- 5/10 layers (0.06 % rad. length each!) seems feasible

Virtual goal: ATLAS pixel upgrade

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 1st half 2007

PSI, Univ. Nijmegen, NIKHEF,

Gossip projects at NIKHEFUniv. Twente/SaclayCERNPSIEUDET

- Discharge protection- InGrid/TwinGrid/TripleGrid- Construction of detector: MediPix2 + SiProt + InGrid- Construction of detector: TimePix + SiProt + InGrid- Beam Telescope with CMS PSI 46 pixel chip- Ageing studies- CO2 cooling

Gossip: the electronic bubble chamber

NIKHEF Harry van der GraafJan TimmermansJan VisschersMaximilien ChefdevilleVladimir GromovRuud KluitFred HartjesEls KoffemanMartin Fransen

Saclay CEA DAPNIA Paul ColasYannis GiomatarisDan Burke

Univ. Twente/Mesa+ Jurriaan SchmitzCora SalmSander SmitsVictor Blanco Carballo

CERN Erik HeineMedipix Consortium

Thanks to:Wim GotinkJoop Rovenkamp

Sr-90 β-source

1.2 mm