Transcript Readout of a TPC with the MEDIPIX2 CMOS chip as direct

Readout of a TPC with the MEDIPIX2 CMOS chip as direct anode
Saclay/DAPNIA
Thanks to:
P. Colas
I. Giomataris
NIKHEF
A.
H.
J.
J.
CERN/MEDIPIX2
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:TimePixGrid:
Why?
A monolithic CMOS Si pixel
sensor with integrated
Micromegas (made in Wafer
Post Processing Technology)
Drift Field
TimePixGrid
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 X0);
- best possible TPC (or drift chamber) performance due to
the detection of single electrons:
- position and drift time coordinates;
- dE/dX measurement;
- extreme low occupancy (109 channels!),
thus best possible track separation;
- recognition (and suppressing) of -rays;
- little back-migrating ions;
- low costs: 180 k€/m2 (2003 estimate)
- no ageing.
CMOS Pixel chip
Proof-of-Principle with
MEDIPIX2 CMOS chip
and triple GEM
Drift
Space
GEM foils
MEDIPIX2 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
55Fe source
No source; exposure 10 s.
Drift length: 100 mm; bottom GEM-MediPix distance 6.6 mm.
Note wide charge distribution, probably due to diffusion.
55Fe
MEDIPIX2
MEDIPIX2 & Micromegas
CMOS 0.25 mm technology
256 x 256 pixels
Pixel dimensions: 55 x 55 mm2
Per pixel: preamp, discriminator,
thresh. dac’s, counter,
communication logic
Cathode (drift) plane
Micromegas
Drift space: 15 mm
Baseplate
MEDIPIX2 pixel sensor
Brass spacer block
Printed circuit board
Aluminum base plate
Developed for X-ray imaging by
the Medipix Collaboration, based
at CERN
Micromegas
55Fe,
1s
55Fe,
10s
400 mm
500 mm
No source, 1s
14 mm
55Fe
Friday 13 (!) Feb 2004: signals from a
source (220 e- per photon); 300 mm x 500
mm clouds as expected
We always knew, but never saw: the
55
conversion of Fe quanta in Ar gas