GOSSIP & the ATLAS SCT Upgrade Max Chefdeville NIKHEF, Amsterdam ATLAS Upgrade Workshop CERN, Oct 1, 2006

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

GOSSIP: Gas On Slimmed SIlicon Pixels CMOS pixel array MIP InGrid Drift gap: 1 mm Max drift time: 16 ns MIP CMOS chip ‘slimmed’ to 30 μm Cathode foil

April 2004Micromegas + MediPix 2 NIKHEF/Saclay/Univ. Twente : MediPix2 pixel sensor Brass spacer block Printed circuit board Aluminum base plate Micromegas Cathode (drift) plane 55 Fe Baseplate Drift space: 15 mm MIPs No source, 1s 55 Fe, 1s He/Isobutane 80/20 Modified MediPix δ-ray! 14 mm

Sr-90 β-source 1.2 mm

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

Prototypes hidden pillars!

Energy resolution in Argon IsoC 4 H 10 80/20 Observation of two lines: K 5.9 keV K 6.4 keV FWHM of the K α distribution 16.7 % Gain fluctuations < 5% Very good energy resolution: Very precise dimensions d < 0.1 μm May 2005

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

CMOS Chip protection against - discharges - sparks - HV breakdowns - too large signals Emperical method: Try RPC technology 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, R vol = 0.2 GΩ/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 Test: put Thorium in gas: Radon α-decays: - large (proportional) signals - Discharges: like short circuits plasma A-Si

UN PROT - no hot plasma on pixel input pads - reduced charge & current Looks like it works! Next: try on Medipix chips Discharge signals: short-circuit between grid and anode due to plasma

A-Si not adequate? Then TwinGrid

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 MIP/cm 2 seems feasible First try

Irradiation with 8 keV X-rays: No rate effects up to anode current density of 0.2 / mm 2  very fast track counting possible! Irradiation with 8 keV X-rays: No rate effects up to anode current density of 0.2 μA / mm 2  very fast track counting possible! After 0.3 Coulomb/mm2:  (eq. 3.7 x MIPs/cm 2 !!) deposit of carbon polymer on anode is clearly visible. Micromegas is clean (!?) Little deposit on cathode, and…… Chamber still worked!

Very low (parasitic) capacitance at the input (C par → 10fF). Input pad Substrate C fb =1fF C par = 10fF…50fF Coaxial-like layout of the input interconnection. Parasitic metal-to-metal fringe capacitances. Ground plane Output C fb R fb C par I in (t) Q in Output Open loop voltage gain of the OPAMP A 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 digital and analog sections Guard rings GND GND_ana VDD_ana P-type substrate P-well N-well Analog P-type FET area Analog N-type FET area Digital N-type FET area substrate current GND GND_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 chip Submitted December 2005.

GOSSIPO-2 test of preamp-shaper-discriminator MHz TDC per pixel 0.13 μm technology containing 16 x 16 pixels Submission Nov 2006 Can be used for GOSSIP demo!

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 in 2030…. ‘balloon’ ‘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 - CO 2 cooling Gossip chip + InGrid drift gap cathode foil ladder cross section data 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 end 2006 Nijmegen, NIKHEF (,PSI?)

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 - (CO 2 cooling: ATLAS/NIKHEF project)

Gossip (SLHC) NIKHEF -Study of ‘services’ required for Gossip/SLHC: assume dose rate of 12 tracks/(cm 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 - Development of ‘beam telescope’ Gossip demo - interface Gossip-ATLAS pixel DAQ system

Gossip: the electronic bubble chamber NIKHEFHarry van der Graaf Jan Timmermans Jan Visschers Maximilien Chefdeville Vladimir Gromov Ruud Kluit Fred Hartjes Els Koffemans Martin Fransen Saclay CEA DAPNIAPaul Colas Yannis Giomataris Dan Burke Univ. Twente/Mesa+Jurriaan Schmitz Cora Salm Sander Smits Victor Blanco Carballo CERNErik Heine Medipix Consortium Thanks to: Wim Gotink Joop Rovenkamp