Direct readout of gaseous detectors with tiled CMOS … readout of gaseous detectors with tiled CMOS...

October 2, 2006 Siena IPRD06 1

Direct readout of gaseous detectors with tiled CMOS pixel circuitsJan Timmermans - NIKHEF

• Micro Pattern Gas Detector: GridPix• Integration of grid and readout: InGrid• 3D readout: TimePix• Discharge protection• Future developments


Goals • Gas multiplication GEM or Micromegas foil(s)• Charge collection with granularity matching primary

ionisation cluster spread(this needs sufficiently low diffusion gas)

• Investigate measurement dE/dx using cluster counting

• 2D “proof of principle” based on existing Medipix2 readout chip: achieved

• Add 3rd coordinate: Medipix2 → TimePix• Integrate grid with pixel chip: InGrid (new results)

October 2, 2006 3

Micro Patterned Gaseous Detectors

GEM

Micromegas

• High field created by Gas Gain Grids

• Most popular: GEM & Micromegas

Use ‘naked’ CMOS pixel readout chip as anode

4

Results pixel readout gas detectors

Observation of min. ionising cosmic muons: high spatial resolution + individual cluster counting !

δ ray

NIKHEF-Saclay-CERN-Twente

NIM A540 (2005) 295 (physics/0409048)

55x55 µm2

pixels

Ar/isobutane95/5


(from Freiburg GEM+Medipix setup - Andreas Bamberger)

Difference between Micromegas and GEM setup understood (simulation Michael Hauschild/CERN)

~ 50 µm resolution

Triple GEM

Total gain ~60k

October 2, 2006October 2, 2006 Siena IPRD06Siena IPRD06 66

InGridIntegrate GEM/Micromegas and pixel sensor

‘GEM’ ‘Micromegas’

By ‘wafer post processing’

19 different fields of 15 mm 19 different fields of 15 mm ØØ2 bonding pads / fields2 bonding pads / fields

44”” waferwafer


NIKHEF/Twente: InGrid (Integrated Grid)

Deposit anode Deposit SU-8

UV exposure Deposit metal

Pattern metal Develop resist


Measuring the InGrid signals ( NIM A556 (2006) 490 )

(After 9 months of process tuning and unsuccessful trials)

Pulseheight and gain: He + 20% iC4H10

•Gas gains 103 - 6·104


Energy resolution in Argon IsoC4H10 80/20

•Observation of two lines:

Kα at 5.9 keV

Kβ at 6.4 keV

•Resolution σE/E = 6.5%

(FWHM = 15.3%)

•Gain variations < ±5%

•Photo peak asymmetry seen

•Very good energy resolution


Gas gains in Argon

•Ar / CO2 mixtures offer good ageing properties

•Gain of 104 reachable in Ar / CO2 80/20

•Ageing studies in a reasonable amount of time (intense X-rays source)


Any field structure feasible


Gain for different gap sizesMaximum predicted in gain vs gap curve

deM α=

Gap (mm)

Y. Giomataris/N.I.M. A419 (1998) 239-250

0.001 0.01 0.1 11

10

1000

100

10000

Gai

n

V=400Volts

V=350Volts

V=300Volts

d gap thickness

p pressure

A,B depend on gasmixture


Gain for different gap sizes• But now we can make measurements

Grid voltage

Gai

n

300 380 460 540102

103

104

105

Gap thickness (µm)35 45 6555 75

400V450V500V

75um35um55um40um


Homogeneity• Gain measurements scanning the surface of the detector• Homogeneity given by grid quality

2.6 % RMS 1.6 % RMSx yyx

Gain Gain


Simulated gain for different hole size• Electric field along z axis decreases with hole size• Different gain expected for different hole size

Hole size (µm)0 10 20 30 40

Gai

nGrid

400V 103

104

Z(µm)0 20 40 60 80

E(k

V.c

m-1

)

10

30

50

70 10µm hole

50µm hole

z = distance from anode


Measured gain for different hole size

And measurements confirm simulationsG

ain

103

104

102

Vgrid460420 540500


Energy resolution• Resolution depends on

– Primary,attachment,T,P– Collection efficiency (field ratio)– Gain homogeneity & transverse diffusion

103 10410

20

30

40

60

Res

olut

ion

(FW

HM

%)

Gain


Resolution as function of gap

• Why a parabolic behavior ?

Vgrid

Res

olut

ion

(FW

HM

%)

20

30

40

50 35um55um75um

380 420 460 500

Gain

Energy resolution

F. Jeanneau et al. NIM A 461 (2001) 84–87

19

TimePix1(EUDET: Freiburg, Saclay, CERN, NIKHEF)

•Distribute clock to full 256x256 pixel matrix (50-100-160MHz)•Enable counting by first hit after ‘shutter’ opens, until ‘shutter’closes (common stop); also time-over-threshold possible

•Dynamic range 214 x 10 ns = 160 µs

•(for the time being) no zero-suppress to remain fully compatible with Medipix2

•Shaping time ~200 ns

•Keep same chip-size, pixel-size, readout protocol•1st full reticle submit done July 2006; first results just now: very encouraging!

11 22 44

55

66

55µm

55µm


TimepixTimepix TOTTOT

17

100MHz 100MHz


Timepix summary Timepix summary Physical dimensions 14.111 mm x 16.120 mm (like Mpix2MXR20)

Charge collection e-, h+

Linearity Up to 50Ke-

σ equalized ~25e-

Minimum Threshold ~500e- (expected)*

Max Analog power 6.5µW/pix 420mW/chip (@2.2V Vdda)Static Digital Power 440mW@100MHz (@2.2V Vdd)Readout Serial/ParallelReadout compatibility 95% (Clock active when shutter ON)

IO PADs 127 (like Mpix2MXR20)

Pixel functionality PhotonCounting, TOT, TimepixAmplifier Gain ~18mV/Ke-

Noise ~75e-

Thresholds 1 (4bits adj)

Counter Depth/Overflow 14-bits/Yes


Sparking• Chip faces 80kV/cm with no protection (unlike

the GEM setup; 1.5 yr using same chip)• Degradation of the field, or total destruction

of grid but also CMOS chip

10µm


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

Silicon Protection: SiProt

Amorph Si (segmented)

Empirical method:Try RPC technology


- 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; avoid wafers get too hot

Univ. of Neuchatel/IMT/P. Jarron (CERN) uses this forintegrated X-ray sensor/convertor on MediPix 2

--- -

plasma A-Si

Test: put Thorium in gas: Radon α-decays:- large (proportional) signals- Discharges: like short circuits


UN

UN

UN

PROT

- no hot plasma onpixel input pads

- reduced charge & current

Looks like it works!

Discharge signals:short-circuit betweengrid and anodedue to plasma

PROT

PROT


Alternative: TwinGrid

GOSSIP: Gas On Slimmed SIlicon Pixels(as a possible vertex/track detector at SLHC)

CMOS pixel array

MIP

InGrid

Drift gap: 1 mmMax drift time: 16 ns

MIP

CMOS chip‘slimmed’ to 30 µm

Cathode foil


Sr-90 β-source

1.2 mm


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!

•source capacity 15 fF

•peaking time 40 ns

•expected noise ~60 e-

•power: 2 µW/pixel


Further DevelopmentsRELAXD project (Dutch/Belgian)

NIKHEF,Panalytical,IMEC,Canberra:• Chip tiling: large(r) detector surfaces

(2x2, 2x4 chips)• Through Si connectivity: avoiding bonding wires• Fast readout technology

(~5 Gb/s)

October 2, 2006October 2, 2006 Siena IPRD06Siena IPRD06 3131

GridPix: the electronic bubble chamber

NIKHEF Harry van der GraafJan TimmermansJan VisschersMaximilien ChefdevilleMartin FransenVladimir Gromov

Saclay CEA DAPNIA Paul Colas, David AttiééDan Burke,Yannis GiomatarisArnoud Giganon

Univ. Twente/Mesa+ Jurriaan SchmitzCora SalmVictor Blanco CarballoSander Smits

CERN Michael Campbell,Erik HeineXavi Llopart

Thanks to:Wim GotinkJoop Rovenkamp

Direct readout of gaseous detectors with tiled CMOS … readout of gaseous detectors with tiled CMOS...

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