gossip a new vertex detector for atlas harry van der graaf nikhef, amsterdam univ. of bonn, nov 23,...

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