1. Status ‘Si readout’ TPC at NIKHEF NIKHEFAuke-Pieter Colijn Alessandro Fornaini Harry van der Graaf Peter Kluit Jan Timmermans Jan Visschers Saclay CEA DAPNIAMaximilien Chefdeville Paul Colas Yannis Giomataris Arnaud Giganon Univ. Twente/Mesa+Jurriaan Schmitz CERN/Medipix ConstmErik Heijne Xavie Llopart Michael Campbell Thanks to: Wim Gotink Joop Rovenkamp ECFA Workshop Durham 3/9/2004 PhD student per 1/9/04

2. Goals Gas multiplication GEM or Micromegas foil(s) Charge collection with granularity matching primary ionisation cluster spread Needs sufficiently low diffusion gas dE/dx using cluster counting? (  M. Hauschild) Proof of principle based on existing Medipix2 readout chip

3. MediPix2 pixel sensor Brass spacer block Printed circuit board Aluminum base plate Micromegas Cathode (drift) plane 55 Fe Baseplate Drift space: 15 mm With Paul Colas & Ioannis Giomataris: MediPix2 & Micromegas Very strong E-field above (CMOS) MediPix!

6. He/Isobutane 80/20 Modified MediPix Sensitive area: 14 x 14 x 15 mm 3 Drift direction: Vertical max = 15 mm 31 March 2004

7. He/Isobutane 80/20 Modified MediPix 31 March 2004

8. He/Isobutane 80/20 Modified MediPix 31 March 2004

9. He/Isobutane 80/20 Modified MediPix δ-ray? 31 March 2004

10. Example of a track reconstructed This track: #hits = 24 #clusters = 11 length (3d) = 16.8 mm 1.4 e - /mm; 0.65 cl./mm On average: 1.8 e - /mm; 0.5 cl./mm

11. Detection of single electrons using MediPix2/Micromegas assembly as Direct Pixel Segmented Anode Analysis of cosmic data 31/3-2/4 finalised NIM paper submitted 31/8/04 #pixels hit/mm track length = 1.83 #clusters/mm track length = 0.52 Single electron efficiency 0.9 Moire effects: mismatch in pixel and hole pitch: 60/(60-55) = 12 pixels repetition

12. Non Modified Modified Explanation for Moire effect:pitch Micromegas holes: 60 μm pitch MediPix pixels:55 μm Periodic position of hole w.r.t. pixel: repeats after 12 pixels!

13. Modified Non Modified InGrid: perfect alignment of pixels and grid holes! Small pad: small capacitance!

14. Integrate GEM/Micromegas and pixel sensor ‘GEM’‘Micromegas’ By ‘wafer post processing’ InGrid

15. Wafer dia.: 100 mm 30 fields with variety of pillar geometry First trials with pillars look OK Some problems with ‘Micromegas’ grid (hope to have first sample in few weeks

16. INGRID: some first trials Various pitches, shapes

18. Other applications of TimePixGrid: - μ-TPC (e.g. KABES in NA48/3 ?) - upgrades of TPCs: STAR, ALICE - Transition Radiation Detectors - GOSSIP: tracker for intense radiation environment

19. CMOS pixel array MIP Micromegas GOSSIP: Gas On Slimmed SIlicon Pixels Drift gap: 1 mm Max drift time: 10 ns MIP CMOS pixel chip Cathode foil

20. Essentials of GOSSIP: Generate charge signal in gas instead of Si (e-/ions versus e-/holes) Amplify # electrons in gas (electron avalanche versus FET preamps) Then: No radiation damage in depletion layer or pixel preamp FETs No power dissipation of preamp FETs GOSSIP:1 mm gas layer + 20 μm gain gap + CMOS (digital!) chip After all: it is a TPC with 1 mm drift length (parallax!) Max. drift length: 1 mm Max. drift time: 10 ns Resolution: 0.1 mm  1 ns

21. Efficiency Position resolution Rate effects Ageing Radiation hardness HV breakdowns Power dissipation Material budget More details in http://www.nikhef.nl/~d90/tesla/NIPHAD_GOSSIP.ppt http://www.nikhef.nl/~d90/tesla/NIPHAD_GOSSIP.ppt

22. Ongoing/Coming activities: Cosmic trigger setup ready New Micromegas available very soon (Paul C.) New Medipix2 available First Ingrid1 tests Simulations Longer term: Ingrid2 together with MediPix Development of Timepix1 (for TPC) and Timepix2 (for GOSSIP) CMOS chips New collaborators are welcomed!