New gaseous detectors:

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New gaseous detectors the application of pixel
sensors as direct anode
Harry van der Graaf NIKHEF, Amsterdam IEEE-NSS
Conference, Rome N17-4, Oct 19, 2004
NIKHEF Auke-Pieter Colijn Alessandro
Fornaini Harry van der Graaf Peter
Kluit Jan Timmermans Jan Visschers Maximilie
n Chefdeville Saclay CEA DAPNIA Paul
Colas Yannis Giomataris Arnaud
Giganon Univ. Twente/Mesa Jurriaan
Schmitz CERN/Medipix Constm Eric Heijne Xavie
Llopart Michael Campbell
Thanks to Wim Gotink Joop Rovenkamp
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Original motivation Si pixel readout for the
Time Projection Chamber (TPC) at TESLA (now ILC)
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Time Projection Chamber (TPC) 2D/3D Drift
Chamber The Ultimate Wire (drift) Chamber
track of charged particle
E-field (and B-field)
Wire plane
Wire Plane Readout Pads
Pad plane
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Wireless wire chambers better granularity
1995 Giomataris Charpak MicroMegas
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Wireless wire chambers better granularity
1996 F. Sauli Gas Electron Multiplier (GEM)
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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)
avalanche
GEM
wire
Micromegas
Cathode pads
Solutions - cover pads with resisitive layer -
Chevron pads - many small pads pixels
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The MediPix2 pixel CMOS chip
Cathode foil
Drift Space
Gem foils
Support plate
Medipix 2
We apply the naked MediPix2 chip without X-ray
convertor!
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MediPix2 Micromegas
55Fe
Cathode (drift) plane
Drift space 15 mm
Micromegas
Baseplate
MediPix2 pixel sensor Brass spacer block Printed
circuit board Aluminum base plate
Very strong E-field above (CMOS) MediPix!
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14 mm
Signals from a 55Fe source (220 e- per photon)
300 ?m x 500 ?m clouds as expected
The Medipix CMOS chip faces an electric field of
350 V/50 µm 7 kV/mm !!
We always knew, but never saw the conversion of
55Fe quanta in Ar gas
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Single electron efficiency

• no attachment
• homogeneous field in
• avalanche gap
• low gas gain
• ?
• No Curran or Polya
• distributions but simply

Prob(n) 1/G . e-n/G
Eff e-Thr/G
Thr threshold setting (e-) G Gas amplification
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New trial NIKHEF, March 30 April 2,
2004 Essential try to see single electrons from
cosmic muons (MIPs) Pixel preamp threshold 3000
e- Required gain 5000 10.000 New Medipix New
Micromegas Gas He/Isobutane 80/20 Ar/Isobutane
80/20 He/CF4 80/20 It Works!
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He/Isobutane 80/20 Modified MediPix
Sensitive area 14 x 14 x 15 mm3
Drift direction Vertical max 15 mm
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He/Isobutane 80/20 Modified MediPix
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He/Isobutane 80/20 Modified MediPix
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He/Isobutane 80/20 Non Modified MediPix Americi
um Source
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He/Isobutane 80/20 Modified MediPix
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He/Isobutane 80/20 Modified MediPix
d-ray!
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• After 24 h cosmic ray data and 3 broken chips
• We can reach very high gas gains with He-based
  gases (gt 100k!)
• The MedPix2 chip can withstand strong E-fields
  (10 kV/mm!)
• Discharges ruin the chip immediately (broke 4 in
  4 days!)
• Measured efficiency gt 0.9 consistent with high
  gain
• Seen MIPs, clusters, d-rays, electrons, a s
• - In winter 2004 beam tests (dE/dX e-, pions,
  muons,),
• X-rays (ESRF, Grenoble)
• - Development of TimePix 1 TDC per pixel instead
  of counter

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Integrate GEM/Micromegas and pixel sensor InGrid
GEM
Micromegas
Monolitic detector by wafer post processing
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InGrid
By wafer post processing at MESA, Univ. of
Twente
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HV breakdowns
1) High-resistive layer
3) massive pads
2) High-resistive layer
4) Protection Network
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Other application GOSSIP tracker for intense
radiation environment Vertex detector for SLHC
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An thin TPC as vertex detector
GOSSIP Gas On Slimmed SIlicon Pixels
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• Essentials of GOSSIP
• Generate charge signal in gas instead of Si
  (e-/ions versus e-/holes)
• Amplify electrons in gas (electron avalanche
  versus FET preamps)
• Then
• No radiation damage in depletion layer or pixel
  preamp FETs
• No power dissipation of preamps
• No detector bias current
• Ultralight detection layer (Si foil 1 mm Ar
  gas)
• 1 mm gas layer 20 µm gain gap CMOS (almost
  digital!) chip
• After all it is a TPC with 1 mm drift length
  (parallax error!)

Max. drift length 1 mm Max. drift time 16
ns Resolution 0.1 mm ? 1.6 ns
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Ageing Power dissipation Material budget Rate
effects Radiation hardness Efficiency Position
resolution
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Ageing
Remember the MSGCs

• Little ageing
• the ratio (anode surface)/(gas volume) is very
  high w.r.t. wire chambers
• little gas gain 5 k for GOSSIP, 20 200 k for
  wire chambers
• homogeneous drift field homogeneous
  multiplication field
• versus 1/R field of wire. Absence of high
  E-field close to a wire
• no high electron energy little production of
  chemical radicals
• Confirmed by measurements (Alfonsi, Colas)
• But critical issue ageing studies can not be
  much accelerated!

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Power dissipation

• For GOSSIP CMOS Pixel chip
• Per pixel
• - input stage (1.8 µA/pixel)
• (timing) logic
• Futher data transfer logic
• guess 0.1 W/cm2
• ? Gas Cooling feasible!

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Detector Material budget
Slimmed Si CMOS chip 30 µm Si Pixel resistive
layer 1 µm SU8 eq. Anode pads 1 µm
Al Grid 1 µm Al Grid resistive layer 5 µm
SU8 eq. Cathode 1 µm Al
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Rate effects
SLHC _at_ 2 cm from beam pipe 10 tracks cm-2 25
ns-1 400 MHz cm-2!

• 10 e- per track (average)
• gas gain 5 k
• most ions are discharged at grid
• after traveling time of 20 ns
• a few percent enter the drift space

time

• Some ions crossing drift space takes 20 200
  µs!
• ion space charge has NO effect on gas gain
• ion charge may influence drift field, but this
  does little harm
• ion charge may influence drift direction change
  in lorentz angle 0.1 rad
• B-field should help

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Efficiency

• Determined by gas layer thickness and gas
  mixture
• Number of clusters per mm 3 (Ar) 10
  (Isobutane)
• Number of electrons per cluster 3 (Ar) - 15
  (Isobutane)
• Probability to have min. 1 cluster in 1 mm Ar
  0.95
• With nice gas eff 0.99 in 1 mm thick layer
  should be possible
• But.
• Parallax error due to 1 mm thick layer, with 3rd
  coordinate 0.1 mm
• TPC/ max drift time 16 ns s 0.1 mm s 1.6
  ns feasible!
• Lorentz angle
• We want fast drifting ions (rate effect)
• little UV photon induced avalanches good
  quenching gas

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Position resolution

• Transversal coordinates limited by
• Diffusion single electron diffusion 0 40/70
  µm
• weighed fit ava 20/30 µm
• 10 e- per track s 8/10 µm
• pixel dimensions 20 x 20 50 x 50 µm2
• Note we MUST have sq. pixels no strips (pad
  capacity/noise)
• Good resolution in non-bending plane!
• Pixel number has NO cost consequence (m2 Si
  counts)
• Pixel number has some effect on CMOS power
  dissipation
• d-rays can be recognised eliminated
• 3rd (drift) coordinate
• limited by
• Pulse height fluctuation
• gas gain (5 k), pad capacity, e- per cluster
• With Time Over Threshold s 1 ns 0.1 mm

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Radiation hardness

• Gas is refreshed no damage
• CMOS 130 nm technology TID
• NIEL
• SEU design/test
• need only modest pixel input stage

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• Gas instead of Si
• Pro
• no radiation damage in sensor
• modest pixel input circuitry
• no bias current, no dark current (in absence of
  HV breakdowns..!)
• requires (almost) only digital CMOS readout chip
• low detector material budget
• low power dissipation
• (12) CMOS wafer ? Wafer Post Processing
• no bump bonding
• simple assembly
• operates at room temperature
• less sensitive for X-ray background
• 3D track info per layer
• Con
• Gas chamber ageing not known at this stage
• Needs gas flow (but can be used for cooling.)

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• Plans
• InGrid 1 available for tests in November
• rate effects
• ageing (start of test test takes years)
• ? Proof-of-principle of signal
  generator Xmas 2004!
• InGrid 2 HV breakdowns, beamtests with MediPix
  (TimePix1 in 2005)
• Gossipo Multi Project Wafer test chip

Dummy wafer
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New gaseous detectors the application of pixel
sensors as direct anode
Harry van der Graaf NIKHEF, Amsterdam IEEE-NSS
Conference, Rome N17-4, Oct 19, 2004
NIKHEF Auke-Pieter Colijn Alessandro
Fornaini Harry van der Graaf Peter
Kluit Jan Timmermans Jan Visschers Maximilie
n Chefdeville Saclay CEA DAPNIA Paul
Colas Yannis Giomataris Arnaud
Giganon Univ. Twente/Mesa Jurriaan
Schmitz CERN/Medipix Constm Eric Heijne Xavie
Llopart Michael Campbell
Thanks to Wim Gotink Joop Rovenkamp