GOSSIP & the ATLAS SCT Upgrade

Max ChefdevilleNIKHEF, Amsterdam

ATLAS Upgrade WorkshopCERN, Oct 1, 2006

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

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

Sr-90 β-source

1.2 mm

Integrate Micromegas and pixel sensor:

InGrid

‘wafer post processing’by

Univ. of Twente, MESA+’

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

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

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

Emperical method:Try RPC technology

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 GΩ/cm

TechnologyA-Si deposit possible in general, 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

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

A-Si not adequate? Then TwinGrid

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

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!

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

Input pad

Substrate

Cfb=1fF

Cpar = 10fF…50fF

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

fringe capacitances.

Ground plane

Output

Cfb

Rfb

Cpar Iin(t)

Qin

Output

Open loop voltage gain of the OPAMP

A

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.

GOSSIPO-2

test of preamp-shaper-discriminator

+

700 MHz TDC per pixel

• 0.13 μm technology• containing 16 x 16 pixels• Submission Nov 2006• Can be used for GOSSIP demo!

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’

- 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 end 2006

Nijmegen, NIKHEF (,PSI?)

Gossip projects at NIKHEF/Univ. Twente/Saclay/CERN

- Discharge protection- InGrid/TwinGrid/TripleGrid- Construction of detector: MediPix2 + SiProt + InGrid- Construction of detector: TimePix + SiProt + InGrid- Ageing studies

- (CO2 cooling: ATLAS/NIKHEF project)

Gossip (SLHC) projects @ NIKHEF

-Study of ‘services’ required for Gossip/SLHC: assume dose rate of 12 tracks/(cm2 . 25 ns)

- definition of data transfer connection;- definition of cooling;- definition of power lines

- Ladder prototype:- thermal modeling;- Design of SS/Alu multifunctional string;- test (mech + thermal) of mechanical model

- Gossipo chip developments

- vertex track simulations- signal development- DAQ data streams

- Development of ‘beam telescope’ Gossip demo- interface Gossip-ATLAS pixel DAQ system

Gossip: the electronic bubble chamber

NIKHEF Harry van der GraafJan TimmermansJan VisschersMaximilien ChefdevilleVladimir GromovRuud KluitFred HartjesEls KoffemansMartin 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