Post on 05-Jan-2016
GOSSIPa new vertex detector for ATLAS
Harry van der GraafNIKHEF, Amsterdam
Univ. of Bonn, Nov 23, 2006
New gaseous detectors:the application of pixel sensors as direct anode
NIKHEF Auke-Pieter ColijnAlessandro FornainiHarry van der GraafPeter KluitJan TimmermansJan VisschersMaximilien
Chefdeville
Saclay CEA DAPNIA Paul ColasYannis GiomatarisArnaud Giganon
Univ. Twente/Mesa+ Jurriaan Schmitz
CERN/Medipix Constm Eric HeijneXavie LlopartMichael CampbellThanks to:
Wim GotinkJoop RovenkampArnaud Giganon
Harry van der Graaf, NIKHEF, Amsterdam
University of Bonn Oct 14, 2004
GOSSIP: Gas On Slimmed SIlicon Pixels
CMOS pixel array
MIP
InGrid
Drift gap: 1 mmMax. drift time: 16 ns
MIP
CMOS pixel chip‘slimmed’ to 30 μm
Cathode foil
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
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
Integrate Micromegas and pixel sensor:
InGrid
‘wafer post processing’by
Univ. of Twente, MESA+’“there is plenty of room at the top”
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
A-Si not adequate? Then TwinGrid
Gas instead of Si Pro
Low mass detector!
- low power: 2 μW/pixel (analog), 0.6 μW/pixel (digital) Total 2.6 μW/pixel 0.1 W/cm2 due to:
- extremely low source capacitance (10 fF)- fast & arbitrary large charge signals- no bias current
little material required for power & cooling
- Thinning (Slimming) of CMOS pixel chip to 50 μm
detection layer: only 0.06 % radiation length
new vertex detector: 5 – 10 layers instead of 3
Input pad
Substrate
Cfb=1fF
Ground plane
Output
M1
M2
M3
M6
LM
Ground
Gas instead of Si Pro
- a GOSSIP detector measures a track segment instead of a point-in-space:
- single-electron sensitive (eff > 95 %)- ~ 10 e- along 1 mm track length- spatial resolution: 50 μm / √10 = 15 μm
14 mm3
- radiation hardness- gas is flushed- CMOS chip (130, 90, 45 nm technology): sufficiently radiation hard for SLHC
- very low sensitivity for neutrons, X-rays and gammas- ‘simple’ CMOS chip:
- modest (small area) analog input circuits- no bias current: simpeler input circuit- pixel area available for data storage & communication
- Cheap
Gas instead of Si Con
- GOSSIP has 1 mm detection layer:
- parallax error: elimination requires drift time measurement- with single-electron measurement: track segment data per layer!
- Gas-filled detector:
- chamber ageing (deposit on electrodes)- discharges (sparks, too large signals) ruin CMOS chip
showstoppers !
CMOS Chip protection against - discharges- sparks- HV breakdowns- too large signals
Emperical method:Try RPC principle
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 – 100 GΩ/cm
TechnologyA-Si deposit: standard wafer post processing, 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
The SiProt chamberThe SiProt chamberLow temperature deposition (< 250Low temperature deposition (< 250°°C) of a C) of a 4 4 μμm thick a-Sim thick a-Si layer of layer of 10101111 ΩΩ.cm .cm resistivityresistivity
Experimental setup:Experimental setup:– 1 bare anode and 1 a-Si covered anode with Micromegas on top1 bare anode and 1 a-Si covered anode with Micromegas on top– Gain curve with an Iron 55 sourceGain curve with an Iron 55 source– Induce discharges by means of 5 MeV alphas from Th source Induce discharges by means of 5 MeV alphas from Th source in gasin gas– Record grid signalsRecord grid signals
Micromegas grids
prot. anode
un-prot. anode
Aluminum
a-Si
To digital scope or pre-amplifier
SiProt chamberTh container
Digitalscope
cathode
Discharge Discharge Signals studySignals study
No preamplifierNo preamplifier
Ar 20 % iCAr 20 % iC44HH1010
Signals from ~ 5 MeV alphasSignals from ~ 5 MeV alphasFast digital scopeFast digital scope
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
55Fesource
Look at the pulses from a (calibrated) preamplifier (low grid voltage)
Look at the current flowing through the power supply (high grid voltage)
No sparks up to 570 V on the grid !
Next step: SiProt (and InGrid) on Medipix, TimePix
from current
from pulse height
Gain in Ar 20 iso
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
1.00E+07
1.00E+08
1.00E+09
300 400 500 600
HV (V)
Ga
in
Unprotected
Protected (currentmode)
Protected (pulsemode)
Gain measurement
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
Ageing: remember the MSGCs….
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!
Ongoing projects
Very low (parasitic) capacitanceat the input (Cpar → 10fF) .
Cpar = 10fF…50fF
Coaxial-like layout of the input interconnection.Parasitic metal-to-metal
fringe capacitances.
Cfb
Rfb
Cpar Iin(t)
Qin
Output
Open loop voltage gain of the OPAMP
A
Input pad
Substrate
Cfb=1fF
Ground plane
Output
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.
test ofpreamp-shaper-discriminator
and
700 MHz TDC per pixel
• 0.13 μm technology• containing 16 x 16 pixels• Submission Nov 29, 2006• Can be used for GOSSIP demo!
GOSSIPO-2
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
‘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 1st half 2007
PSI, Univ. Nijmegen, NIKHEF,
Gossip projects at NIKHEFUniv. Twente/SaclayCERNPSIEUDET
- Discharge protection- InGrid/TwinGrid/TripleGrid- Construction of detector: MediPix2 + SiProt + InGrid- Construction of detector: TimePix + SiProt + InGrid- Beam Telescope with CMS PSI 46 pixel chip- Ageing studies- CO2 cooling
Gossip: the electronic bubble chamber
NIKHEF Harry van der GraafJan TimmermansJan VisschersMaximilien ChefdevilleVladimir GromovRuud KluitFred HartjesEls KoffemanMartin 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
Sr-90 β-source
1.2 mm