Readout of a TPC with the MEDIPIX 2

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Readout of a TPC with the MEDIPIX 2 CMOS chip as direct anode Saclay/DAPNIA

Readout of a TPC with the MEDIPIX 2 CMOS chip as direct anode Saclay/DAPNIA Thanks to: P. Colas I. Giomataris NIKHEF A. H. J. J. CERN/MEDIPIX 2 E. Heijne NIKHEF Wim Gotink Joop Rovenkamp Dimitri John Jan Martis Ad Berkien, Frank de Zwart Edward Berbee Ton Boerkamp Jan van Veen Saclay Arnaud Giganon Fornaini van der Graaf Timmermans Visschers Univ. Twente/MESA+ J. Schmitz Goal: Time. Pix. Grid: Why? A monolithic CMOS Si pixel sensor with integrated Micromegas (made in Wafer Post Processing Technology) Drift Field Time. Pix. Grid spacer Micromegas Avalanche Gap - replaces anode wires (or GEMs, or Micromegas), pads, cables, feedthrough & readout electronics in drift chambers; - simplifies construction of TPC endcap (aluminium gas cover with glued-on naked chips) considerably (small X 0); - best possible TPC (or drift chamber) performance due to the detection of single electrons: - position and drift time coordinates; - d. E/d. X measurement; - extreme low occupancy (109 channels!), thus best possible track separation; - recognition (and suppressing) of -rays; - little back-migrating ions; - low costs: 180 k€/m 2 (2003 estimate) - no ageing. CMOS Pixel chip Proof-of-Principle with MEDIPIX 2 CMOS chip and triple GEM Drift Space GEM foils MEDIPIX 2 pixel sensor Brass spacer block Printed circuit board Aluminium base plate March 2003 Feb 2004 Ar/Methane 90/10 Ar/Isobutane 95/5 Triple GEM spaced 1. 6 mm Triple GEM spaced 2. 6 mm 55 Fe source No source; exposure 10 s. Drift length: 100 mm; bottom GEM-Medi. Pix distance 6. 6 mm. Note wide charge distribution, probably due to diffusion. 55 Fe MEDIPIX 2 & Micromegas CMOS 0. 25 m technology 256 x 256 pixels Pixel dimensions: 55 x 55 m 2 Per pixel: preamp, discriminator, thresh. dac’s, counter, communication logic Cathode (drift) plane Micromegas Drift space: 15 mm Baseplate MEDIPIX 2 pixel sensor Brass spacer block Printed circuit board Aluminum base plate Developed for X-ray imaging by the Medipix Collaboration, based at CERN Micromegas 55 Fe, 10 s 400 m 500 m No source, 1 s 14 mm 55 Fe Friday 13 (!) Feb 2004: signals from a source (220 e- per photon); 300 m x 500 m clouds as expected We always knew, but never saw: the 55 conversion of Fe quanta in Ar gas