1. TPC
Paul Colas
Technical meeting, Lyon

2. Technologies under study
25/04/2017
Paul Colas - TPC
Technologies under study
MPGDs suffer less from ExB effects than MWPCs. They require less heavy mechanics. Panels with each technology have been made and tested.
European GEMs
Micromegas
Standard kapton triple GEM with ceramic spacers
Mesh on top of a
charge-dispersing resistive anode
GridPix
Integrated grid on 55 µ digital pixels
Asian GEMs

3. Eu GEM modules : flatness improved
25/04/2017
Paul Colas - TPC
Eu GEM modules : flatness improved
Quality control: foil flatness
GEM stack of 2 modules measured
flat by almost a factor of two
GEM stacks: 6.1% → 4.2%
PREVIOUS
CURRENT

4. 25/04/2017
Paul Colas - TPC
For the Eu GEMs, it has been checked that minimizing the ion backflow does not worsen the resolution. (January 2017)

5. Gridpix : ‘digital TPC’
25/04/2017
Paul Colas - TPC
Gridpix : ‘digital TPC’
Reconstruct every ionization electron with a high efficiency. Measure dE/dx by cluster counting
Recently progress has been done with Timepix 3 and chip protection against sparks has been improved.

6. 25/04/2017
Paul Colas - TPC
Distortions
Module frames at ground while the top GEM or Micromesh is at HV induces distortions at the level of O(1mm). New design should suppress this effect.
Eu GEM
Micromegas

7. 25/04/2017
Paul Colas - TPC
Need for gating
In TPCs, ions are produced and migrate very slowly (1 m/s) . They produce a charge density which can be one or two orders of magnitude above the primary ionization (IBF*Gain). The resulting electric field can be the origin of distortions.
At the ILC, the bunch trains last about 1ms every 200 ms, giving rise to ion disks slowly drifting to the cathode

8. 25/04/2017
Paul Colas - TPC
Need for gating
In TPCs, ions are produced and migrate very slowly (1 m/s) . They produce a charge density which can be one or two orders of magnitude above the primary ionization (IBF*Gain). The resulting electric field can be the origin of distortions.
At the ILC, the bunch trains last about 1ms every 200 ms, giving rise to ion disks slowly drifting to the cathode
After 2 disks, the electrons receive a kick of up to 60 µm, too much wrt the systematics

9. 25/04/2017
Paul Colas - TPC
Gating options
The ions must be stopped before penetrating too much the drift region.
The device to stop them must be transparent to electrons.
Here is the example of a highly transparent wire mesh used to create a counter field near the amplification device

10. 25/04/2017
Paul Colas - TPC
Gating options
The ions must be stopped before penetrating too much the drift region.
The device to stop them must be transparent to electrons.
Here is the example of a GEM with a Delta V polarization.

11. GEM gating – Large aperture GEM transparency
25/04/2017
Paul Colas - TPC
GEM gating – Large aperture GEM transparency

12. 25/04/2017
Paul Colas - TPC

13. Measurement in Japan with GEMs Measurement at CERN with Micromegas
25/04/2017
Paul Colas - TPC
Measurement in Japan with GEMs
Measurement at CERN with Micromegas
Simulation studies in progress
D V (Volts)

14. Test beam results with a gating GEM
25/04/2017
Paul Colas - TPC
Test beam results with a gating GEM
A module with a gating GEM has also been tested in beam in November The results are consistent with no more degradation than expected (~10%)
The analysis is still in progress, but GEM gating seems to be a possible solution for the gating at ILC

15. 25/04/2017
Paul Colas - TPC

16. 25/04/2017
Paul Colas - TPC

17. Magboltz simulation : CD ~94 µm/sqrt(cm)
25/04/2017
Paul Colas - TPC
Magboltz simulation : CD ~94 µm/sqrt(cm)

18. GEM resolution w and w/o gating
25/04/2017
Paul Colas - TPC
GEM resolution w and w/o gating
Consistent with a transparency of 86 %

19. 25/04/2017
Paul Colas - TPC
CO2 cooling
CO2 cooling has been demonstrated (with Micromegas so far). Requires 1mm diameter serpentine
Cables
Each module requires:
A low-voltage cable to supply the electronics (2mm²)
One or several HV cable for the amplification device
A double-fibre for the signals
A cooling tube
Fully integrated design : 0.25 X0

20. The ILD TPC A 8-wheel design A 4-wheel option 2 x 2.3 m length
25/04/2017
Paul Colas - TPC
The ILD TPC
2 x 2.3 m length
Covering radii from 0.35 to 1.7 m
A 8-wheel design
240 modules with about the size of present LP modules.
A 4-wheel option
80 modules each side.
For each module (6800 channels) :
1 HV cable
1 double optical fibre
1 low-voltage 32A cable
160 W to remove (becomes negligeable is power pulsing can be fully implemented.

21. 25/04/2017
Paul Colas - TPC

22. Endplate panels Panel height 336 mm Panel width : from 278 to 454
25/04/2017
Paul Colas - TPC
Endplate panels
Panel height 336 mm
Panel width : from 278 to 454
About 6800 pads per panel

23. 25/04/2017
Paul Colas - TPC
Summary
Despite very difficult conditions, the R&D is still in progress : gating tests are promising, flatness of the EU GEM chambers is improved, pixel readout is getting mature
Realist implementation plans are about to start. This is also a preparation for the technology choice.