GOSSIP

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GOSSIP the ATLAS SCT Upgrade
Max Chefdeville NIKHEF, Amsterdam ATLAS Upgrade
Workshop CERN, Oct 1, 2006
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Si (vertex) track detector GOSSIP
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

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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
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April 2004 Micromegas MediPix
2 NIKHEF/Saclay/Univ. Twente
55Fe, 1s
No source, 1s
55Fe
Cathode (drift) plane
Drift space 15 mm
Micromegas
Baseplate
MediPix2 pixel sensor Brass spacer block Printed
circuit board Aluminum base plate
14 mm
d-ray!
He/Isobutane 80/20 Modified MediPix
MIPs
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Sr-90 ß-source
1.2 mm
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Integrate Micromegas and pixel sensor InGrid
wafer post processing by Univ. of Twente,
MESA
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Prototypes
hidden pillars!
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Energy resolution in Argon IsoC4H10 80/20

• Observation of two lines
• Ka _at_ 5.9 keV
• Kß _at_ 6.4 keV
• FWHM of the Ka distribution
• 16.7
• Gain fluctuations
• lt 5

Very good energy resolution Very precise
dimensions d lt 0.1 µm
May 2005
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• Gas instead of Si
• Pro
• 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

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

• 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 GO/cm

Technology A-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 a-decays -
large (proportional) signals - Discharges like
short circuits
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UN
PROT
Discharge signals short-circuit between grid and
anode due to plasma
UN
PROT

• no hot plasma on
• pixel input pads
• reduced charge
• current
• Looks like it works!
• Next try on Medipix
• chips

UN
PROT
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A-Si not adequate? Then TwinGrid
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Ageing

• Ageing 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
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Irradiation with 8 keV X-raysNo 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!
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GOSSIPO-1 test of preamp-shaper-discriminator
for GOSSIP MultiProjectWafer in 0.13 µm
technology
Input pad
Cpar 10fF50fF
LM
Ground plane
M6
Ground
Output
M3
Very low (parasitic) capacitance at the input
(Cpar ? 10fF) .
Cfb1fF
M2
Coaxial-like layout of the input interconnection.
M1
Parasitic metal-to-metal fringe capacitances.
Substrate
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Triple well layout isolation of
digital and analog sections
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• - match extreme small source capacity 15 fF
• peaking time 40 ns
• noise (expected 60 e- input eq.)
• power 2 µW/pixel (!)

GOSSIPO chip Submitted December 2005.

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

MultiProject Wafer Vladimir Gromov/NIKHEF CERN
Micro-electronics group
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• 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!

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• 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.
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Virtual goal ATLAS pixel upgrade

• - 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

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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
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• 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?)
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• 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)

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• Gossip (SLHC) projects _at_ 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

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NIKHEF Harry van der Graaf Jan
Timmermans Jan Visschers Maximilien
Chefdeville Vladimir Gromov Ruud
Kluit Fred Hartjes Els Koffemans Martin
Fransen Saclay CEA DAPNIA Paul Colas Yannis
Giomataris Dan Burke Univ. Twente/Mesa Jurri
aan Schmitz Cora Salm Sander
Smits Victor Blanco Carballo CERN Erik
Heine Medipix Consortium
Thanks to Wim Gotink Joop Rovenkamp
Gossip the electronic bubble chamber