1. GridPix/Gossip for ATLAS SCT Upgrade ILC CLIC
…….insulators in strong E- fields……….
…….the frustration of innovation………..
Harry van der Graaf
Nikhef, Amsterdam
IEEE-NSS Conference
MPGD-Si Detector Workshop
Dresden, Oct 18, 2008

2. Micro Strip Gas Counters: hard to operate:
discharges, ruining electrodes
ageing
! Very strong electric field in insulator’s volume & surface !

3. GEMs:
often cascade of 3 GEMs used to limit gain per GEM to ~40
‘rim’ (dia hole Cu/kapton) critical
shape of hole wall critical
charge up effects

4. Overview of MPGD development in JAPAN
Atsuhiko OCHI
Kobe University, JAPAN
13 Oct nd RD51 workshop in Paris

5. GEM Production Remove copper by wet etching Irradiate CO2 laser
Recent Status of Development
GEM Production
RIKEN/SciEnergy GEM
(thick-foil and fine-pitch)
pitch 80um
hole 40um
thickness 100um
100um
80um
x750
Remove copper
by wet etching
Irradiate CO2 laser
Remove remaining edge from the other side 5

6. Recent Status of Development
Gain Curve (RIKEN GEM)
GEM test setup and parameters
Thick-foil and fine-pitch GEM
(single layer)
HV supplied through a resister chain
Ed=2.5kV/cm, Ei=4~5kV/cm, ⊿VGEM=300~600V
Gas: Ar+CO2(30%) flow
Readout by 1cm x 1cm pad
Gain measurement
Gain vs applied voltage
X-ray from Fe-55 (5.9keV)
Fe-55 spectrum
5.9keV
gain=3x104
To keep good spatial resolution and keep discharge point at high gain.
Our GEM is most suitable for Cosmic X-ray Polarimeters. 6

7. Gain instability (RIKEN GEM)
Recent Status of Development
Gain instability (RIKEN GEM)
No increase and decrease just after HV on.
F. Simon (IEEE, 2006)
T. Tamagawa(IEEE,2007)
time (s)
relative gain
3 hours
No gain increase in short measurements
This is not for a special batch of GEMs but for all GEMs we
produced
Possible reasons;
Less charging-up due to cylindrical hole shape
Less polarization of Liquid Crystal Polymer 7

8. GemGrid 1
GemGrid 2

9. Bulk high-resistivity materials
hydregenated amorphous silicon
allowed gains up to 5 105
staying proportional!
Si-rich silicon nitride (Si3N4)

10. Measurements on Si-rich Silicon Nitride (Si3N4)
Column resistance: ρ D/O
Potential surface measurable: gain drop factor 2 at dV = 17.5 V
With known current: bulk resistivity ρ measurable: ~ 1 – Ohm cm
Surface time constant: Column resistance x (virtual colum capacitance) =
(ρ D/O)*(ε O/D) = ρ ε (independant of layer thickness D!)

11. Resistive Plate Chambers (RPCs)
essential: high-resistivity material
- quenches sparks
- sufficient charge compensation current
Traditional: insulator + dope (Sardinian oils…?)
New: high-resistivity bulk (ceramic) material: higher counting rates
Compare graphite covered mylar foil

12. conductivity of kapton
Micromegas on pillars
Edge discharge protection foil
discharges + vibrations

14. Charge-up effects
After (rapid) ramping of HV:
polarisation: reduction of E-field in insulator (bulk) volume
In homogeneous field with insulator // to field: nothing
With E component perp. on insulating surface: modification
of potential by hitting e- and/or ions until E // surface

15. GEM hole

16. equalizing with water
Stronger effects for
good insulator
region of
worse insulation

17. Very preliminary:
Use as little as possible insulating surfaces // strong E fields
Apply high-resistivity materials instead of insulators
Even more preliminary:
As for gain: GEMs perform les than (corresponding) Micromegas

18. MIPs April 2004 Micromegas + MediPix 2 NIKHEF/Saclay/Univ. Twente:
No source, 1s
55Fe, 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
δ-ray!
He/Isobutane
80/20
Modified MediPix
MIPs

19. ‘wafer post processing’
Integrate Micromegas and pixel sensor:
InGrid
‘wafer post processing’ by
Univ. of Twente, MESA+’

20. Full post-processing of a TimePix
Timepix chip + SiProt + Ingrid:
14 mm
MESA+
“Uniform”
IMT Neuchatel
Charge mode

21. A “long” cosmic track Timepix + 20 μm thick Siprot Ingrid
cathode @ V
14 mm
10 mm
A “long” cosmic track
Timepix +
20 μm thick Siprot
Ingrid
Drifttime (bin = 10 ns)
Stable operation in He iC4H10

23. Si (vertex) track detector GOSSIP
Cluster3
Cathode (drift) plane
Integrated Grid (InGrid)
Cluster2
Cluster1
Slimmed Silicon Readout chip
Input pixel
1mm,
100V
50um,
400V
50um
CMOS chip
Si depletion layer
Vbias
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

24. Gossip: replacement of Si tracker Essential: thin gas layer (1.2 mm)

25. GOSSIP-Brico: PSI-46 (CMS Pixel FE chip)
First prototype of GOSSIP on a PSI46 is working:
• 1.2 mm drift gap
• Grid signal used as trigger
• 30 µm layer of SiProt

26. Tracking sensor material: gas versus Si
it is light
primary electrons can simply be multiplied: gas amplification: low power
no bias current: low power & simple FE circuits
gas can be exchanged: no radiation damage of sensor
gas has a low εr: with small voxels the source capacity can be small (10 fF)
allowing fast, low-noise, and low-power preamps
gas is usually cheap
low sensitive for neutron and X-ray background
δ-rays can be recognized
[high ion & electron mobility: fast signals, high count rates are possible]
discharges/sparks: readout system should be spark proof
ageing: must be solved and must be understood / under control
diffusion: limits max. drift length

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

28. Qmax ~ 1 – 2 fC
Chip may die if Qmax > 10 fC

29. Ageing Little ageing expected:
Radiation damage of CMOS pixel chip is relevant
- common for all tracking detectors
- believed to widthstand ATLAS Upgrade Dose in 90 nm technology
Radiation damage of sensor:
not relevant for Gossip sensor since this is gas being exchanged
Typical for gaseous detectors: the deposit of an (insulating) polymer
on the electrodes of a detector. Decrease of signal amplitude
Little ageing expected:
little primary ionisation (~ 10 e-/track)
low gas gain (500 – 1000)
large anode surface (compare pixel anode plane with surface of thin wire)
E-field at flat anode ~3 lower than E-field at anode wire

30. gas: standard Ar/Methane 90/10. Deposit containing C found on anode

31. Irradiation with 8 keV X-rays: No 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!
Ageing

32. Construction of many test chambers
prototypes
Next-1,2,3,4,5
Next Quad
Next-64 (ReNexed, ReLaXd)
DICE
Ageing Chambers

33. Next-64 / ReLaXd / ReNexd
CO2 cooling!

34. DICE

35. Reactor
Institute
Delft
RID
DICE
Nuclear Reactor
Water Bassin
10 x 10 x 10 m3

37. Upgraded SCT: Gossip could replace:
Pixel vertex detector: Gossip
Si Strip detectors: replace by Gossip Strixel detectors
TRT: use Gossip as tracker/TR X-ray detector
Essentials:
power dissipation: 60 mW/cm2
intrinsic mass: 0.1 % radiation length
low cost: 10 $ / cm2

38. Barrel SCT unit
EndCap SCT unit

39. Semiconductor (pixel, strip) detectors
Depleted Si, 300 μm
Vbias = 150 V
electron-hole
pairs
(pixel) chip with
preamps, shapers,
discriminators

40. ATLAS pixel: basic element
C-C support
sensor
Flex Hybrid
bumps
MCC
Side view
not to scale
Wire-bonding FE’s
Wire-bonding MCC
FE chip
Flex module 2.x

41. - Ladder strings fixed to end cones
Integration of beam pipe, end cones & pixel vertex detector
5 double layers seems feasible

42. Gossip in ATLAS (Goat-1) Stave
TimePix-2 chip
SiNProt layer
InGrid (Si3N4)
Gas Cover
casted aluminium
power line
‘P’(ositive)String
carrying 1.3 V
‘G’(round)String
gas
manifold
‘Road’: C-fibre reinforced databus + aux services
StainlessSteel tube
for CO2 cooling
Stiff, light Stave formed by G-string
P-string
Road triangle

43. GOAT: GOssip in ATlas Inner Layer: 7 double Goat strings
Gossip readout
Gossip detector unit
Ø60mm Beampipe
P-string conductor
(+voltage)
CO2 cooling channels
G-string conductor
(+voltage)

44. Upgraded SCT: Gossip/GridPix could replace:
Pixel vertex detector: Gossip
Si Strip detectors: replace by Gossip Strixel detectors
TRT: use GridPix as tracker/TR X-ray detector
strixels/strips
preamp channels
~ 20 mm
Essentials:
power dissipation: 1/16 x 60 mW/cm2 = 4 mW/cm2
now:25 mW/cm2
intrinsic mass: 0.1 % radiation length
low cost: 10 $ / cm2

45. Upgraded Tracker: Gossip could replace:
Pixel vertex detector: Gossip
Si Strip detectors: replace by Gossip Strixel detectors
TRT: use Gossip with 17 mm Xe layer
as tracker/TR X-ray detector
Essential:
high position-resolution tracker throughout tracker
low mass, low cost detector
Efficient TRD possible

46. PS/T9: electrons and pions, 1 – 15 GeV/c
Testbeam Nov 5 – 12, 2007
PS/T9: electrons and pions, 1 – 15 GeV/c
L=30 mm V0 V1 f
Transition Radiator
0.05 mm
Anatoli Romaniouk, Serguei Morozov, Serguei Konovalov
Martin Fransen, Fred Hartjes, Max Chefdeville, Victor Blanco Carballo

47. Particle Identification
Samples pions (left) and electrons (right)
6 GeV/c

48. 5 (double) layer Gossip Pixel
4 layer Gossip Strixel
radiator
3 layers Gossip TRT

49. Gas instead of Si Pro: Con:
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
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

50. 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….

51. Minimum Material Budget
(% rad length)
Z = 0 mm
Z = +/-600 mm
Gossip detector (50 μm Si)
Cooling (stainless steel tube)
Power (max 0.28 mm aluminium)
Data transfer (max 1.7 mm kapton)
total
angle correction x √ x 2 x √2 3

52. Virtual goal: ATLAS pixel vertex
- Ladder strings fixed to end cones
Integration of beam pipe, end cones & pixel vertex detector
5 double layers seems feasible

54. Gossip in ATLAS (Goat-1) Stave
TimePix-2 chip
SiNProt layer
InGrid (Si3N4)
Gas Cover
casted aluminium
power line
‘P’(ositive)String
carrying 1.3 V
‘G’(round)String
gas
manifold
‘Road’: C-fibre reinforced databus + aux services
StainlessSteel tube
for CO2 cooling
Stiff, light Stave formed by G-string
P-string
Road triangle

55. GOAT: GOssip in ATlas Inner Layer: 7 double Goat strings
Gossip readout
Gossip detector unit
Ø60mm Beampipe
P-string conductor
(+voltage)
CO2 cooling channels
G-string conductor
(+voltage)

56. The future:
Electron Emission Foil
MEMS made MicroChannelPlates: 200 ps time resolution: CLIC
electron emission foil
electron emission foil
CMOS pixel chip
CMOS pixel chip
replace gas by vacuum
Micro Channel Plate
sub-ns time resolution
Note CLIC experiments
electron avalanche in gas
EE-Foil replaces InGrid
Parallel Plate Chamber

58. July 2005: ATLAS Upgrade Worlshop Genua
Contribution Gossip was refused:
……………..pixel B-layer replacement too soon for new R&D projects…..
Sept 2006: ATLAS Upgrade Workshop Liverpool:
Contribution Gossip was granted (after repeated requests)
Dec 2007: ATLAS Upgrade Workshop Valencia:
Invited to present Gossip R&D project
Sept 2008: PSD8, Glasgow:
keynote: Norbert Wermes: Pixel detectors for charges particles
mentions 3D, Diamond, MAPs, but NOT Gossip

59. Si tracking detectors
the ultimate detector in HEP
associated with Moore’s Law, chip technology
Proposal:
(imaginary) separation of
Interaction Matter and
readout electronics
Integration (MAPs) maybe profitable later

60. Si (vertex) track detector GOSSIP
Cluster3
Cathode (drift) plane
Integrated Grid (InGrid)
Cluster2
Cluster1
Slimmed Silicon Readout chip
Input pixel
1mm,
100V
50um,
400V
50um
CMOS chip
Si depletion layer
Vbias
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

61. NIKHEF
Harry van der Graaf, Max Chefdeville, Fred Hartjes, Jan Timmermans, Jan Visschers, Marten Bosma, Martin Fransen, Yevgen Bilevych,
Wim Gotink, Joop Rovekamp
University of Twente
Cora Salm, Joost Melai, Jurriaan Schmitz, Sander Smits,
Victor Blanco Carballo
University of Nijmegen
Michael Rogers, Thei Wijnen, Adriaan Konig, Jan Dijkema,
Nicolo de Groot
CEA/DAPNIA Saclay
D. Attié, P. Colas, I. Giomataris
CERN
M. Campbell, X. Llopart
University of Neuchatel/MTI
Nicolas Wyrsch
Czech Tech. Univ. Prague, Praha
Pixelman: T. Holy et al.