1. Progress with pixelised readout of gaseous detectors
ALCPG 2011 – Eugene
20 March 2011
Jan Timmermans
NIKHEF/DESY
On behalf of the Bonn/CERN/Freiburg/Nikhef/Saclay groups

2. Full post-processing of a TimePix
· Timepix chip + SiProt + Ingrid:
Timepix chip:
256x256 pixels
pixel: 55x55 μm2
active surface: 14x14 mm2
MESA+: Ingrid
IMT Neuchatel:
15 or 20 μm highly resistive aSi:H protection layer
Now also Si3N4 protection layers (7 μm)

3. Terminology
Timepix = 256x256 pixel CMOS readout chip, with time measurement per pixel
Siprot (amorphous Si) or Si3N4 highly resistive protection layers
Ingrid = Timepix + ‘Siprot’ + integrated (Micromegas-like) conductive grid (NIKHEF and Mesa+ Univ. Twente (NL)); now also at IZM Berlin + Bonn
Octopuce = 8 x Ingrid (NIKHEF/Saclay))

4. Pad readout vs. Pixel readout
Pad size ~1x5 mm2 or ~3x7 mm2
Timepix pixel size 55x55 (μm)2
Pad TPC ~ 106 pads; several D-voxels
CMOS pixel readout ~ ‘pads’ (but ‘only’ ~ chips); ~ D voxels
# pads/pixels might be problem for software, but occupancy “rather low”

5. 72x24 pads of ~3x7 mm2
5 GeV e- beam
B = 1 T
TimePix chip 14x14 mm2

6. Two-track separation: Will be diffusion limited
In this example:
5 pixels = 275 μm
Diffusion at 4T in
Ar/CF4/iC4H10 is
~ 20√200 = 300 μm
256x256 pixels
55x55 (μm)2
275 μm

7. Single chips / 3x3 chip squares at Twente
facilities at Twente U can (at most) handle 4 inch wafers
practically at most 3x3 chips can be handled at once
several days of processing (+ working) time for one run
Try to find a place which can manufacture Ingrids on a 8 inch wafer scale
Best candidate currently: (Berlin)

8. Detector Technologies
3-GEM
8 (2x4) Timepix
InGrid
8 Timepix „Octopuce“
underneath
a 3-GEM
stack
NIKHEF Saclay Twente
Bonn Freiburg

9. Detector Technologies
First „large area“ ( 2.8 x 5.6 cm2, 500k „channels“) tracking devices (EUDET):
3-GEM
8 Timepix
InGrid
8 Timepix
NIKHEF Saclay Twente
Bonn Freiburg

10. 1st attempt at IZM: „GEMGrids“

11. „GEMGrids“ – work (in principle)
first signals
seen in Bonn setup
with 55-Fe source
challenges / problems
limited yield (~ 1 / 6 structures working so far...)
sparking at the edges
limited HV  limited efficiency to be understood
T. Krautscheid, Bonn

12. Activities in 2010 at DESY test beam
4-chip/Ingrid tests in March; 3 days OK
Single Ingrid tests in May combined with EUDET telescope: some synchro problems
Single Ingrid tests in Aug/Sept with Bonnie Chow (DESY summer student); one run combined with ZEUS/MVD telescope; synchro seems OK, some problem with Endianness of various PCs (or software?)
Octopuce (= 8 Ingrids) test on LP with magnet in December together with Saclay group

13. Track backscattering from chip (=anode)

14. Handshaked Pixelman operation
based on Uwe Renz Pixelman plugin
Work performed with Uwe Renz (and Martin Killenberg support) and with DESY summerstudent Bonnie Chow
Detector used is the (2009) “8 um” Ingrid

15. Track scattering at grid (or anode)
Out-of-time track
Beam entering through cathode

16. DESY Nov/Dec test beam e- test beam 5 GeV
Preparation/installation Octopuce detector in gastestbox on Monday 29/11
Some test runs in gastestbox w. beam on Tuesday 30/11
Mounting detector module on LPTPC evening Tuesday 30/11
Flushing with pure He and from morning Wed 1/12 with He/isoButane 80/20 (5-6 hours per 40l gas bottle at 9 bar when full)
First data taking evening Thu 2/12 without B-field
B = 1 T available from Fri 3/12 15:00
Several data taking runs until Sat 4/12 ~12:00
Data taking rather slow (1 Hz), because of only (old) PC that worked with Muros and 8-chips

17. 8 Ingrids on daughter board
LPTPC with 7 detector slots
inside1 T solenoid

18. EUDET 2010 - Octopuce - P. Colas
29/09/2010
EUDET Octopuce - P. Colas 18

19. LCTPC WP phone meeting #119
TPC at 0T
He/Iso 80/20
Vmesh = 380V
Time mode
December 9, 2010
LCTPC WP phone meeting #119 19

20. LCTPC WP phone meeting #119
TPC at 1T
He/Iso 80/20
Vmesh = 380V
Time mode
December 9, 2010
LCTPC WP phone meeting #119 20

21. The last trigger taken: 4 Dec 2010, 11:06
He/iC4H10 80/20 Vgrid = -400 V B = 1 T

22. Summary (including some ‘old’ statements)
8 μm thick Si3N4 protection layers seem sufficient
Problems with readout of 4-fold Timepix/Ingrid (still) being investigated
Successful standalone “handshaked” operation with early shutter opening
Common data acquisition with Zeus telescope, running EUDAQ, succeeded
Short but rather successful data taking with Octopuce module at Large Prototype TPC at B = 0 and 1 T

23. Future
Wafer-scale production of Ingrids/GEMgrids at IZM Berlin (all single steps of process tried out); hopefully 1st successful production in next few months
Construct 2nd Octopuce and test at LP with T2K gas
Move to new (faster) readout: e.g. Muros/Pixelman  “Relaxed”
Longer term (2(?) years): development of “full” scale LP module with ~64 – 119 Ingrids; integrated design Ingrid, cooling, FPGA readout and data transfer
Timepix2 with better time resolution and improved readout

24. 2nd road at IZM: Ingrids transfer original „Twente“ process to 8´´
very successful 1st attempt
on dummy wafers
development after dicing
IZM+Y.Bilevych,Bonn
extremely regular...