GOSSIP & the ATLAS SCT Upgrade

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

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

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

4. April 2004 Micromegas + MediPix 2 NIKHEF/Saclay/Univ. Twente: 55Fe, 1s No source, 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

5. Sr-90 β-source 1.2 mm

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

7. Prototypes hidden pillars!

8. Energy resolution in Argon IsoC4H10 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

9. 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

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

11. plasma A-Si - - - - • 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 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 2 Test: put Thorium in gas: Radon α-decays: - large (proportional) signals - Discharges: like short circuits

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

13. A-Si not adequate? Then TwinGrid

14. 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 • 1016 MIP/cm2 • seems feasible First try

15. 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!

16. Cfb Qin Rfb Output A Iin(t) Cpar Open loop voltage gain of the OPAMP GOSSIPO-1: test of preamp-shaper-discriminator for GOSSIP ‘MultiProjectWafer’ in 0.13 μm technology Input pad Cpar = 10fF…50fF LM Ground plane M6 Ground Output M3 Very low (parasitic) capacitance at the input (Cpar → 10fF). Cfb=1fF M2 Coaxial-like layout of the input interconnection. M1 Parasitic metal-to-metal fringe capacitances. Substrate

17. VDD_ana VDD_ana Guard rings GND GND GND_ana GND_ana Analog N-type FET area Digital N-type FET area Analog P-type FET area P-well P-type substrate N-well substrate current Triple well layout: isolation of digital and analog sections

18. - match extreme small source capacity: 15 fF • peaking time: 40 ns • noise (expected: 60 e- input eq.) • power: 2 μW/pixel (!) GOSSIPO chip Submitted December 2005. • Input noise eq. reached • No effect of digital switching • within pixel MultiProject Wafer: Vladimir Gromov/NIKHEF CERN Micro-electronics group

19. 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!

20. 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….

21. Virtual goal: ATLAS pixel upgrade • - 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

22. data lines (Cu/kapton) ladder cross section casted aluminium Gossip chip + InGrid drift gap cathode foil Stainless steel tube: - string - power - CO2 cooling ladder side view ladder top view

23. 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?)

24. 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 • - (CO2 cooling: ATLAS/NIKHEF project)

25. Gossip (SLHC) projects @ NIKHEF • Study of ‘services’ required for Gossip/SLHC: • assume dose rate of 12 tracks/(cm2 . 25 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

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